Nordin, Annika - Forests in the changing climate

@article{larsson_diminishing_2024,
	title = {Diminishing legacy effects from forest fertilization on stand structure, vegetation community, and soil function},
	volume = {563},
	issn = {0378-1127},
	url = {https://www.sciencedirect.com/science/article/pii/S0378112724002792},
	doi = {10.1016/j.foreco.2024.121967},
	abstract = {While there is consensus that fertilization with nitrogen (N) is a cost-effective way of increasing both forest biomass yield and timber harvest profitability, the strength and longevity of legacy effects are debated. To quantify legacy effects of past fertilization, we analysed 21 mixed Pinus sylvesteris and Picea abies stands. The stands, on average 23 years old at the time of this study, were either unfertilized (n=7), fertilized with 150 kg N ha−1 once 36 years ago (n=7), or twice, 45 and 36 years ago, respectively (n=7), during the previous stand rotation. We performed measurements on soil N mineralisation and N availability, forest growth, ground vegetation community composition, soil and vegetation C/N ratios and soil C and N stocks, many of which responded to legacy N fertilization earlier in stand development. Our results show that the legacy effects of fertilization during the previous stand rotation have diminished through time, indicating an eventual convergence of stand properties. Specifically, all significant effects present in the previous measurement period (over a decade ago), were weaker or completely absent in the current study (i.e. 36 years after fertilization and 23 years after initiation of the new stands). None-the-less, this indicates a longer legacy effect of N fertilization than what is normally considered and suggests that care should be taken to mitigate unwanted, long-term effects when utilizing N addition to promote tree growth in boreal forests.},
	urldate = {2024-05-15},
	journal = {Forest Ecology and Management},
	author = {Larsson, Marcus and Strengbom, Joachim and Gundale, Michael J. and Nordin, Annika},
	month = jul,
	year = {2024},
	keywords = {Forest fertilization, Forest growth, Ion-exchange resin, Mineralization, Soil organic carbon, Vegetation community composition},
	pages = {121967},
}

While there is consensus that fertilization with nitrogen (N) is a cost-effective way of increasing both forest biomass yield and timber harvest profitability, the strength and longevity of legacy effects are debated. To quantify legacy effects of past fertilization, we analysed 21 mixed Pinus sylvesteris and Picea abies stands. The stands, on average 23 years old at the time of this study, were either unfertilized (n=7), fertilized with 150 kg N ha−1 once 36 years ago (n=7), or twice, 45 and 36 years ago, respectively (n=7), during the previous stand rotation. We performed measurements on soil N mineralisation and N availability, forest growth, ground vegetation community composition, soil and vegetation C/N ratios and soil C and N stocks, many of which responded to legacy N fertilization earlier in stand development. Our results show that the legacy effects of fertilization during the previous stand rotation have diminished through time, indicating an eventual convergence of stand properties. Specifically, all significant effects present in the previous measurement period (over a decade ago), were weaker or completely absent in the current study (i.e. 36 years after fertilization and 23 years after initiation of the new stands). None-the-less, this indicates a longer legacy effect of N fertilization than what is normally considered and suggests that care should be taken to mitigate unwanted, long-term effects when utilizing N addition to promote tree growth in boreal forests.

@article{haggstrom_effects_2024,
	title = {Effects of {Planting} {Position}, {Seedling} {Size}, and {Organic} {Nitrogen} {Fertilization} on the {Establishment} of {Scots} {Pine} ({Pinus} sylvestris {L}.) and {Norway} {Spruce} ({Picea} abies ({L}.) {Karst}) {Seedlings}},
	volume = {15},
	copyright = {http://creativecommons.org/licenses/by/3.0/},
	issn = {1999-4907},
	url = {https://www.mdpi.com/1999-4907/15/4/703},
	doi = {10.3390/f15040703},
	abstract = {The forest regeneration phase in Sweden commonly involves mechanical soil preparation followed by the planting of Scots pine (Pinus sylvestris L.) or Norway spruce (Picea abies (L.) Karst) seedlings. The prepared soil offers planting positions with different properties, including reduced damage by pine weevils (Hylobius abietis L.). Nitrogen fertilization can be applied at the time of planting to aid establishment of the seedlings. In this study, we compared the effects of different planting positions, organic nitrogen fertilization, and different seedling sizes on the early survival and growth of Scots pine and Norway spruce seedlings. The main planting positions were capped mound, hinge, and mineral soil. Seedlings planted close to organic material were categorized as being in “low-quality positions”, since proximity to organic material increases pine weevil attraction. Higher mortality rates related to pine weevil damage were recorded for the seedlings planted in the low-quality positions, regardless of seedling size or N fertilization. Pine weevil attack rates increased with increasing seedling size. Growth was, in general, lowest in the mineral soil positions. The effect of organic N fertilization on growth was positive for the spruce regardless of the planting position or seedling size, while it depended on the planting position and seedling size for the pine, indicating that the effects of organic N fertilization depend on the seedling species, seedling size, and planting position.},
	language = {en},
	number = {4},
	urldate = {2024-05-10},
	journal = {Forests},
	author = {Häggström, Bodil and Hajek, Jörgen and Nordin, Annika and Öhlund, Jonas},
	month = apr,
	year = {2024},
	note = {Number: 4
Publisher: Multidisciplinary Digital Publishing Institute},
	keywords = {Norway spruce, Scots pine, forest regeneration, organic N fertilization, pine weevil, planting position, seedling size},
	pages = {703},
}

The forest regeneration phase in Sweden commonly involves mechanical soil preparation followed by the planting of Scots pine (Pinus sylvestris L.) or Norway spruce (Picea abies (L.) Karst) seedlings. The prepared soil offers planting positions with different properties, including reduced damage by pine weevils (Hylobius abietis L.). Nitrogen fertilization can be applied at the time of planting to aid establishment of the seedlings. In this study, we compared the effects of different planting positions, organic nitrogen fertilization, and different seedling sizes on the early survival and growth of Scots pine and Norway spruce seedlings. The main planting positions were capped mound, hinge, and mineral soil. Seedlings planted close to organic material were categorized as being in “low-quality positions”, since proximity to organic material increases pine weevil attraction. Higher mortality rates related to pine weevil damage were recorded for the seedlings planted in the low-quality positions, regardless of seedling size or N fertilization. Pine weevil attack rates increased with increasing seedling size. Growth was, in general, lowest in the mineral soil positions. The effect of organic N fertilization on growth was positive for the spruce regardless of the planting position or seedling size, while it depended on the planting position and seedling size for the pine, indicating that the effects of organic N fertilization depend on the seedling species, seedling size, and planting position.

@article{forsmark_shifts_2024,
	title = {Shifts in microbial community composition and metabolism correspond with rapid soil carbon accumulation in response to 20 years of simulated nitrogen deposition},
	volume = {918},
	issn = {0048-9697},
	doi = {10.1016/j.scitotenv.2024.170741},
	abstract = {Anthropogenic nitrogen (N) deposition and fertilization in boreal forests frequently reduces decomposition and soil respiration and enhances C storage in the topsoil. This enhancement of the C sink can be as strong as the aboveground biomass response to N additions and has implications for the global C cycle, but the mechanisms remain elusive. We hypothesized that this effect would be associated with a shift in the microbial community and its activity, and particularly by fungal taxa reported to be capable of lignin degradation and organic N acquisition. We sampled the organic layer below the intact litter of a Norway spruce (Picea abies (L.) Karst) forest in northern Sweden after 20 years of annual N additions at low (12.5 kg N ha−1 yr−1) and high (50 kg N ha−1 yr−1) rates. We measured microbial biomass using phospholipid fatty-acid analysis (PLFA) and ergosterol measurements and used ITS metagenomics to profile the fungal community of soil and fine-roots. We probed the metabolic activity of the soil community by measuring the activity of extracellular enzymes and evaluated its relationships with the most N responsive soil fungal species. Nitrogen addition decreased the abundance of fungal PLFA markers and changed the fungal community in humus and fine-roots. Specifically, the humus community changed in part due to a shift from Oidiodendron pilicola, Cenococcum geophilum, and Cortinarius caperatus to Tylospora fibrillosa and Russula griseascens. These microbial community changes were associated with decreased activity of Mn-peroxidase and peptidase, and an increase in the activity of C acquiring enzymes. Our results show that the rapid accumulation of C in the humus layer frequently observed in areas with high N deposition is consistent with a shift in microbial metabolism, where decomposition associated with organic N acquisition is downregulated when inorganic N forms are readily available. © 2024 The Authors},
	language = {English},
	number = {170741},
	journal = {Science of the Total Environment},
	author = {Forsmark, B. and Bizjak, T. and Nordin, A. and Rosenstock, N.P. and Wallander, H. and Gundale, M.J.},
	month = feb,
	year = {2024},
	keywords = {Boreal forest, Carbon sequestration, Ectomycorrhizal fungi, Extracellular enzymes, Microbial community, Nitrogen deposition},
}

Anthropogenic nitrogen (N) deposition and fertilization in boreal forests frequently reduces decomposition and soil respiration and enhances C storage in the topsoil. This enhancement of the C sink can be as strong as the aboveground biomass response to N additions and has implications for the global C cycle, but the mechanisms remain elusive. We hypothesized that this effect would be associated with a shift in the microbial community and its activity, and particularly by fungal taxa reported to be capable of lignin degradation and organic N acquisition. We sampled the organic layer below the intact litter of a Norway spruce (Picea abies (L.) Karst) forest in northern Sweden after 20 years of annual N additions at low (12.5 kg N ha−1 yr−1) and high (50 kg N ha−1 yr−1) rates. We measured microbial biomass using phospholipid fatty-acid analysis (PLFA) and ergosterol measurements and used ITS metagenomics to profile the fungal community of soil and fine-roots. We probed the metabolic activity of the soil community by measuring the activity of extracellular enzymes and evaluated its relationships with the most N responsive soil fungal species. Nitrogen addition decreased the abundance of fungal PLFA markers and changed the fungal community in humus and fine-roots. Specifically, the humus community changed in part due to a shift from Oidiodendron pilicola, Cenococcum geophilum, and Cortinarius caperatus to Tylospora fibrillosa and Russula griseascens. These microbial community changes were associated with decreased activity of Mn-peroxidase and peptidase, and an increase in the activity of C acquiring enzymes. Our results show that the rapid accumulation of C in the humus layer frequently observed in areas with high N deposition is consistent with a shift in microbial metabolism, where decomposition associated with organic N acquisition is downregulated when inorganic N forms are readily available. © 2024 The Authors

@article{hallberg-sramek_combining_2023,
	title = {Combining scientific and local knowledge improves evaluating future scenarios of forest ecosystem services},
	volume = {60},
	issn = {2212-0416},
	url = {https://www.sciencedirect.com/science/article/pii/S2212041623000049},
	doi = {10.1016/j.ecoser.2023.101512},
	abstract = {Forest scenario analysis can help tackle sustainability issues by generating insight into the potential long-term effects of present-day management. In northern Sweden, forests provide important benefits including climate change mitigation, biodiversity conservation, reindeer husbandry, local livelihoods, and recreation. Informed by local stakeholders’ views on how forests can be enabled to deliver these benefits, we created four forest management scenarios: the close-to-nature scenario (CTN) which emphasises biodiversity conservation, the classic management scenario (CLA) optimising the forests’ net present value, the intensified scenario (INT) maximising harvested wood from the forest, and the combined scenario (COM) applying a combination of measures from the CTN and INT. The scenarios were applied to the local forest landscape and modelled over a 100-year simulation period, and the results of the modelling were then evaluated by a diverse group of stakeholders. For most ecosystem services, there was a time lag of 10–50 years before noticeable effects and differences between the scenarios became evident, highlighting the need to consider both the short- and long-term effects of forest management. Evaluation by the stakeholders put the modelled results into a local context. They raised considerations relating to wildlife and hunting, climate change risks, social acceptability, and conflict, highlighting the value of evaluating the scenarios qualitatively as well as quantitatively. Overall, stakeholders thought that the CTN and CLA scenarios promoted more ecosystem services and posed fewer climate risks, while also creating less conflict among stakeholders. Our results emphasise the value of combining scientific and local knowledge when developing and evaluating future forest scenarios.},
	language = {en},
	urldate = {2023-03-10},
	journal = {Ecosystem Services},
	author = {Hallberg-Sramek, Isabella and Nordström, Eva-Maria and Priebe, Janina and Reimerson, Elsa and Mårald, Erland and Nordin, Annika},
	month = apr,
	year = {2023},
	keywords = {Forest management, Indigenous and local knowledge, Inter- and transdisciplinary research, Knowledge co-production, Scenario modelling, Stakeholder participation},
	pages = {101512},
}

Forest scenario analysis can help tackle sustainability issues by generating insight into the potential long-term effects of present-day management. In northern Sweden, forests provide important benefits including climate change mitigation, biodiversity conservation, reindeer husbandry, local livelihoods, and recreation. Informed by local stakeholders’ views on how forests can be enabled to deliver these benefits, we created four forest management scenarios: the close-to-nature scenario (CTN) which emphasises biodiversity conservation, the classic management scenario (CLA) optimising the forests’ net present value, the intensified scenario (INT) maximising harvested wood from the forest, and the combined scenario (COM) applying a combination of measures from the CTN and INT. The scenarios were applied to the local forest landscape and modelled over a 100-year simulation period, and the results of the modelling were then evaluated by a diverse group of stakeholders. For most ecosystem services, there was a time lag of 10–50 years before noticeable effects and differences between the scenarios became evident, highlighting the need to consider both the short- and long-term effects of forest management. Evaluation by the stakeholders put the modelled results into a local context. They raised considerations relating to wildlife and hunting, climate change risks, social acceptability, and conflict, highlighting the value of evaluating the scenarios qualitatively as well as quantitatively. Overall, stakeholders thought that the CTN and CLA scenarios promoted more ecosystem services and posed fewer climate risks, while also creating less conflict among stakeholders. Our results emphasise the value of combining scientific and local knowledge when developing and evaluating future forest scenarios.

@article{svensson_early_2023,
	title = {Early and repeated nutrient additions support far greater stemwood production in {Norway} spruce than traditional late-rotation fertilisation},
	volume = {549},
	issn = {0378-1127},
	url = {https://www.sciencedirect.com/science/article/pii/S037811272300659X},
	doi = {10.1016/j.foreco.2023.121425},
	abstract = {Silvicultural techniques aimed at promoting forest biomass production can help meet the growing demand for renewable materials and mitigate climate change. One-time nitrogen (N) addition late in the rotation is a well-established method to stimulate growth in coniferous forests in northern Europe, but the potential gains from earlier and repeated fertiliser application remain uncertain. Here, we tested the impact of repeated fertilisation in juvenile Norway spruce stands across 9 sites covering a wide range of growing conditions over a 700 km stretch from central to southern Sweden. We tested the fertilisation effects using two separate studies: i) an interval trial with a fertilisation frequency of one (F1), two (F2), or three years (F3) performed at plot-level across five sites (2002–2014), and ii) a practice-oriented trial with a two-year fertilisation interval (F2) applied at stand-level and replicated at four sites (2003–2013). The composition of the nutrient mix in each plot was optimised based on foliar nutrient analyses. In the interval trial, all three fertilisation schedules strongly increased periodic annual increment (PAI) (F1: 105 \%, F2: 93 \%, F3: 79 \%) relative to the unfertilised control, resulting in more than a doubling of stem volume yield in the F1 and F2 treatments (110 \% and 120 \%, respectively) and a significantly smaller but still sizeable yield stimulation of 82 \% in the F3 treatment. Nitrogen use efficiency (NUE, stemwood volume increase per unit mass of N added) was similar among fertilisation intervals (on average 130 m3 ha−1 1000 kg N−1), indicating that the extra N provided through yearly fertilisation (F1) is redundant given the similar stemwood yields in the F2 treatment. In the practice-oriented trial, the sole F2 treatment increased PAI by 95 \% over the control, translating into a yield stimulation of 114 \% and an almost identical NUE to that of the interval trial. NUE greatly exceeded the figures typically observed with traditional late-rotation fertilisation and correlated inversely with baseline site productivity (using site index as a proxy) in the F1 and F2 treatments (the latter pooled across the two trials). Our results clearly indicate that nutrient limitation restricts growth and carbon (C) capture in young Norway spruce plantations in northern Europe to less than half of their potential, highlighting repeated fertilisation at nutrient-poor sites as an effective management tool to support a growing bioeconomy and enhance C sequestration.},
	urldate = {2023-11-03},
	journal = {Forest Ecology and Management},
	author = {Svensson, Carl and Bader, Martin Karl-Friedrich and Forsmark, Benjamin and Nilsson, Urban and Lundmark, Tomas and Nordin, Annika and Bergh, Johan},
	month = dec,
	year = {2023},
	keywords = {Carbon sequestration, Forest fertilisation, Nutrient-limitation, Operational forestry, Stem biomass yield},
	pages = {121425},
}

Silvicultural techniques aimed at promoting forest biomass production can help meet the growing demand for renewable materials and mitigate climate change. One-time nitrogen (N) addition late in the rotation is a well-established method to stimulate growth in coniferous forests in northern Europe, but the potential gains from earlier and repeated fertiliser application remain uncertain. Here, we tested the impact of repeated fertilisation in juvenile Norway spruce stands across 9 sites covering a wide range of growing conditions over a 700 km stretch from central to southern Sweden. We tested the fertilisation effects using two separate studies: i) an interval trial with a fertilisation frequency of one (F1), two (F2), or three years (F3) performed at plot-level across five sites (2002–2014), and ii) a practice-oriented trial with a two-year fertilisation interval (F2) applied at stand-level and replicated at four sites (2003–2013). The composition of the nutrient mix in each plot was optimised based on foliar nutrient analyses. In the interval trial, all three fertilisation schedules strongly increased periodic annual increment (PAI) (F1: 105 %, F2: 93 %, F3: 79 %) relative to the unfertilised control, resulting in more than a doubling of stem volume yield in the F1 and F2 treatments (110 % and 120 %, respectively) and a significantly smaller but still sizeable yield stimulation of 82 % in the F3 treatment. Nitrogen use efficiency (NUE, stemwood volume increase per unit mass of N added) was similar among fertilisation intervals (on average 130 m3 ha−1 1000 kg N−1), indicating that the extra N provided through yearly fertilisation (F1) is redundant given the similar stemwood yields in the F2 treatment. In the practice-oriented trial, the sole F2 treatment increased PAI by 95 % over the control, translating into a yield stimulation of 114 % and an almost identical NUE to that of the interval trial. NUE greatly exceeded the figures typically observed with traditional late-rotation fertilisation and correlated inversely with baseline site productivity (using site index as a proxy) in the F1 and F2 treatments (the latter pooled across the two trials). Our results clearly indicate that nutrient limitation restricts growth and carbon (C) capture in young Norway spruce plantations in northern Europe to less than half of their potential, highlighting repeated fertilisation at nutrient-poor sites as an effective management tool to support a growing bioeconomy and enhance C sequestration.

@article{haggstrom_effect_2023,
	title = {Effect of arginine-phosphate addition on early survival and growth of {Scots} pine, {Norway} spruce and silver birch},
	volume = {57},
	url = {https://www.silvafennica.fi/article/22013},
	doi = {10.14214/sf.22013},
	language = {en},
	number = {2},
	urldate = {2023-09-29},
	journal = {Silva Fennica},
	author = {Häggström, Bodil and Lutter, Reimo and Lundmark, Tomas and Sjödin, Fredrik and Nordin, Annika},
	month = sep,
	year = {2023},
}

@article{haggstrom_environmental_2023,
	title = {Environmental controls on seedling establishment in a boreal forest: implications for {Scots} pine regeneration in continuous cover forestry},
	issn = {1612-4677},
	shorttitle = {Environmental controls on seedling establishment in a boreal forest},
	url = {https://doi.org/10.1007/s10342-023-01609-1},
	doi = {10.1007/s10342-023-01609-1},
	abstract = {In nutrient poor and dry forest sites common to northern Scandinavia, Scots pine (Pinus sylvestris L.) is the most common species both in managed and natural forests. However, Scots pine is sensitive to competition during establishment. Harvesting of all trees within a given area, i.e., clear-cutting, liberates regenerating seedlings from competition with mature trees. However, recently, clear-cut-free or continuous cover forestry has been the subject of substantial debate. When choosing a management method, it is important to recognize how competitive interactions direct the success of Scots pine regeneration. We studied Scots pine regeneration at three environments: beneath the canopy of mature trees, at the canopy edge in full sunlight, and distant from the canopy with no influence of mature trees. We imposed three treatments in each of these environments: root isolation (i.e., trenching), nitrogen (N) fertilization, and control plots. Root isolation enhanced seedling performance under the canopy of mature trees. Nitrogen fertilization enhanced seedling performance to a greater extent in the clear-cut than at the forest edge. However, N fertilization had no effect under the canopy. In the N-fertilized plots, we measured higher N content in the soil under the canopy than in the open environments, indicating that not all excess N was obtained by the mature trees. N-uptake might have been limited by competition for water in the N-fertilized plots. Our results suggest that belowground competition limits the success of regeneration of Scots pine. However, N fertilization presents a tool to compensate for underground competition along canopy edges.},
	language = {en},
	urldate = {2023-12-08},
	journal = {European Journal of Forest Research},
	author = {Häggström, Bodil and Gundale, Michael J. and Nordin, Annika},
	month = oct,
	year = {2023},
	keywords = {Belowground competition, Clear-cutting, Continuous cover forestry, Forest growth, Scots pine, Tree regeneration},
}

In nutrient poor and dry forest sites common to northern Scandinavia, Scots pine (Pinus sylvestris L.) is the most common species both in managed and natural forests. However, Scots pine is sensitive to competition during establishment. Harvesting of all trees within a given area, i.e., clear-cutting, liberates regenerating seedlings from competition with mature trees. However, recently, clear-cut-free or continuous cover forestry has been the subject of substantial debate. When choosing a management method, it is important to recognize how competitive interactions direct the success of Scots pine regeneration. We studied Scots pine regeneration at three environments: beneath the canopy of mature trees, at the canopy edge in full sunlight, and distant from the canopy with no influence of mature trees. We imposed three treatments in each of these environments: root isolation (i.e., trenching), nitrogen (N) fertilization, and control plots. Root isolation enhanced seedling performance under the canopy of mature trees. Nitrogen fertilization enhanced seedling performance to a greater extent in the clear-cut than at the forest edge. However, N fertilization had no effect under the canopy. In the N-fertilized plots, we measured higher N content in the soil under the canopy than in the open environments, indicating that not all excess N was obtained by the mature trees. N-uptake might have been limited by competition for water in the N-fertilized plots. Our results suggest that belowground competition limits the success of regeneration of Scots pine. However, N fertilization presents a tool to compensate for underground competition along canopy edges.

@article{bizjak_presence_2023,
	title = {Presence and activity of nitrogen-fixing bacteria in {Scots} pine needles in a boreal forest: a nitrogen-addition experiment},
	volume = {43},
	issn = {1758-4469},
	shorttitle = {Presence and activity of nitrogen-fixing bacteria in {Scots} pine needles in a boreal forest},
	url = {https://doi.org/10.1093/treephys/tpad048},
	doi = {10.1093/treephys/tpad048},
	abstract = {Endophytic nitrogen-fixing bacteria have been detected and isolated from the needles of conifer trees growing in North American boreal forests. Because boreal forests are nutrient-limited, these bacteria could provide an important source of nitrogen for tree species. This study aimed to determine their presence and activity in a Scandinavian boreal forest, using immunodetection of nitrogenase enzyme subunits and acetylene-reduction assays of native Scots pine (Pinus sylvestris L.) needles. The presence and rate of nitrogen fixation by endophytic bacteria were compared between control plots and fertilized plots in a nitrogen-addition experiment. In contrast to the expectation that nitrogen-fixation rates would decline in fertilized plots, as seen, for instance, with nitrogen-fixing bacteria associated with bryophytes, there was no difference in the presence or activity of nitrogen-fixing bacteria between the two treatments. The extrapolated calculated rate of nitrogen fixation relevant for the forest stand was 20 g N ha−1 year−1, which is rather low compared with Scots pine annual nitrogen use but could be important for the nitrogen-poor forest in the long term. In addition, of 13 colonies of potential nitrogen-fixing bacteria isolated from the needles on nitrogen-free media, 10 showed in vitro nitrogen fixation. In summary, 16S rRNA sequencing identified the species as belonging to the genera Bacillus, Variovorax, Novosphingobium, Sphingomonas, Microbacterium and Priestia, which was confirmed by Illumina whole-genome sequencing. Our results confirm the presence of endophytic nitrogen-fixing bacteria in Scots pine needles and suggest that they could be important for the long-term nitrogen budget of the Scandinavian boreal forest.},
	number = {8},
	urldate = {2023-08-21},
	journal = {Tree Physiology},
	author = {Bizjak, Tinkara and Sellstedt, Anita and Gratz, Regina and Nordin, Annika},
	month = aug,
	year = {2023},
	pages = {1354--1364},
}

Endophytic nitrogen-fixing bacteria have been detected and isolated from the needles of conifer trees growing in North American boreal forests. Because boreal forests are nutrient-limited, these bacteria could provide an important source of nitrogen for tree species. This study aimed to determine their presence and activity in a Scandinavian boreal forest, using immunodetection of nitrogenase enzyme subunits and acetylene-reduction assays of native Scots pine (Pinus sylvestris L.) needles. The presence and rate of nitrogen fixation by endophytic bacteria were compared between control plots and fertilized plots in a nitrogen-addition experiment. In contrast to the expectation that nitrogen-fixation rates would decline in fertilized plots, as seen, for instance, with nitrogen-fixing bacteria associated with bryophytes, there was no difference in the presence or activity of nitrogen-fixing bacteria between the two treatments. The extrapolated calculated rate of nitrogen fixation relevant for the forest stand was 20 g N ha−1 year−1, which is rather low compared with Scots pine annual nitrogen use but could be important for the nitrogen-poor forest in the long term. In addition, of 13 colonies of potential nitrogen-fixing bacteria isolated from the needles on nitrogen-free media, 10 showed in vitro nitrogen fixation. In summary, 16S rRNA sequencing identified the species as belonging to the genera Bacillus, Variovorax, Novosphingobium, Sphingomonas, Microbacterium and Priestia, which was confirmed by Illumina whole-genome sequencing. Our results confirm the presence of endophytic nitrogen-fixing bacteria in Scots pine needles and suggest that they could be important for the long-term nitrogen budget of the Scandinavian boreal forest.

@article{hallberg-sramek_bringing_2022,
	title = {Bringing “{Climate}-{Smart} {Forestry}” {Down} to the {Local} {Level}—{Identifying} {Barriers}, {Pathways} and {Indicators} for {Its} {Implementation} in {Practice}},
	volume = {13},
	copyright = {http://creativecommons.org/licenses/by/3.0/},
	issn = {1999-4907},
	url = {https://www.mdpi.com/1999-4907/13/1/98},
	doi = {10/gn3n2b},
	abstract = {The theoretical concept of “climate-smart forestry” aims to integrate climate change mitigation and adaptation to maintain and enhance forests’ contributions to people and global agendas. We carried out two local transdisciplinary collaboration processes with the aim of developing local articulations of climate-smart forestry and to identify barriers, pathways and indicators to applying it in practice. During workshops in northern and southern Sweden, local stakeholders described how they would like forests to be managed, considering their past experiences, future visions and climate change. As a result, the stakeholders framed climate-smart forestry as active and diverse management towards multiple goals. They identified several conditions that could act both as barriers and pathways for its implementation in practice, such as value chains for forest products and services, local knowledge and experiences of different management alternatives, and the management of ungulates. Based on the workshop material, a total of 39 indicators for climate-smart forestry were identified, of which six were novel indicators adding to the existing literature. Our results emphasize the importance of understanding the local perspectives to promote climate-smart forestry practices across Europe. We also suggest how the concept of climate-smart forestry can be further developed, through the interplay between theory and practice.},
	language = {en},
	number = {1},
	urldate = {2022-03-16},
	journal = {Forests},
	author = {Hallberg-Sramek, Isabella and Reimerson, Elsa and Priebe, Janina and Nordström, Eva-Maria and Mårald, Erland and Sandström, Camilla and Nordin, Annika},
	month = jan,
	year = {2022},
	keywords = {adaptation, climate change, forest policy, interdisciplinary research, mitigation, nature’s contributions to people, stakeholder participation, sustainable forest management, transdisciplinary collaboration},
	pages = {98},
}

The theoretical concept of “climate-smart forestry” aims to integrate climate change mitigation and adaptation to maintain and enhance forests’ contributions to people and global agendas. We carried out two local transdisciplinary collaboration processes with the aim of developing local articulations of climate-smart forestry and to identify barriers, pathways and indicators to applying it in practice. During workshops in northern and southern Sweden, local stakeholders described how they would like forests to be managed, considering their past experiences, future visions and climate change. As a result, the stakeholders framed climate-smart forestry as active and diverse management towards multiple goals. They identified several conditions that could act both as barriers and pathways for its implementation in practice, such as value chains for forest products and services, local knowledge and experiences of different management alternatives, and the management of ungulates. Based on the workshop material, a total of 39 indicators for climate-smart forestry were identified, of which six were novel indicators adding to the existing literature. Our results emphasize the importance of understanding the local perspectives to promote climate-smart forestry practices across Europe. We also suggest how the concept of climate-smart forestry can be further developed, through the interplay between theory and practice.

@article{domevscik_large-scale_2022,
	title = {Large-scale assessment of artificially coated seeds for forest regeneration across {Sweden}},
	issn = {1573-5095},
	url = {https://doi.org/10.1007/s11056-022-09920-2},
	doi = {10.1007/s11056-022-09920-2},
	abstract = {We report the results of two years’ field performance of Scots pine (Pinus sylvestris) seedlings regenerated using artificially coated seeds. The coated seeds were used for regeneration on 12 clearcut sites, covering a 1000 km latitudinal gradient across Sweden. The coating was either combined with arginine-phosphate fertilizer (10 mg N per seed) or had no additions. Interactions with environmental variables associated with sites were also assessed. Coated seeds were deployed in May–June 2017 and surveyed in August–September of 2018 and 2019. After two years, the mean establishment rate of seedlings from coated seeds was 56 ± 4\% across the 12 sites. The fertilizer addition did not affect survival, and the biomass response to fertilizer varied significantly between sites. Maximum precipitation and wind speed during the first six weeks after deployment were correlated with seedling survival, regardless of fertilization treatment. Establishment increased with increasing precipitation and decreased with increasing wind speed. This highlights the importance of initial weather conditions for the seeds’ establishment. Our data suggest that Scots pine regeneration using coated seeds can be practiced in boreal forests, but also that the method is sensitive to the weather conditions at the time of deployment of the seeds.},
	language = {en},
	urldate = {2022-05-20},
	journal = {New Forests},
	author = {Domevscik, Matej and Häggström, Bodil and Lim, Hyungwoo and Öhlund, Jonas and Nordin, Annika},
	month = may,
	year = {2022},
	keywords = {Boreal forest, Coated seeds, Forest regeneration, Scots pine, SeedPAD, Seeding},
}

We report the results of two years’ field performance of Scots pine (Pinus sylvestris) seedlings regenerated using artificially coated seeds. The coated seeds were used for regeneration on 12 clearcut sites, covering a 1000 km latitudinal gradient across Sweden. The coating was either combined with arginine-phosphate fertilizer (10 mg N per seed) or had no additions. Interactions with environmental variables associated with sites were also assessed. Coated seeds were deployed in May–June 2017 and surveyed in August–September of 2018 and 2019. After two years, the mean establishment rate of seedlings from coated seeds was 56 ± 4% across the 12 sites. The fertilizer addition did not affect survival, and the biomass response to fertilizer varied significantly between sites. Maximum precipitation and wind speed during the first six weeks after deployment were correlated with seedling survival, regardless of fertilization treatment. Establishment increased with increasing precipitation and decreased with increasing wind speed. This highlights the importance of initial weather conditions for the seeds’ establishment. Our data suggest that Scots pine regeneration using coated seeds can be practiced in boreal forests, but also that the method is sensitive to the weather conditions at the time of deployment of the seeds.

@article{kauppi_managing_2022,
	title = {Managing existing forests can mitigate climate change},
	volume = {513},
	issn = {0378-1127},
	url = {https://www.sciencedirect.com/science/article/pii/S0378112722001803},
	doi = {10.1016/j.foreco.2022.120186},
	abstract = {Planting new forests has received scientific and political attention as a measure to mitigate climate change. Large, new forests have been planted in places like China and Ethiopia and, over time, a billion hectares could become available globally for planting new forests. Sustainable management of forests, which are available to wood production, has received less attention despite these forests covering at least two billion hectares globally. Better management of existing forests would improve forest growth and help mitigate climate change by increasing the forest carbon (C) stock, by storing C in forest products, and by generating wood-based materials substituting fossil C based materials or other CO2-emission-intensive materials. Some published research assumes a trade-off between the timber harvested from existing forests and the stock of C in those forest ecosystems, asserting that both cannot increase simultaneously. We tested this assumption using the uniquely detailed forest inventory data available from Finland, Norway and Sweden, hereafter denoted northern Europe. We focused on the period 1960 – 2017, that saw little change in the total area covered by forests in northern Europe. At the start of the period, rotational forestry practices began to diffuse, eventually replacing selective felling management systems as the most common management practice. Looking at data over the period we find that despite significant increases in timber and pulp wood harvests, the growth of the forest C stock accelerated. Over the study period, the C stock of the forest ecosystems in northern Europe increased by nearly 70\%, while annual timber harvests increased at the about 40\% over the same period. This increase in the forest C stock was close to on par with the CO2-emissions from the region (other greenhouse gases not included). Our results suggest that the important effects of management on forest growth allows the forest C stock and timber harvests to increase simultaneously. The development in northern Europe raises the question of how better forest management can improve forest growth elsewhere around the globe while at the same time protecting biodiversity and preserving landscapes.},
	language = {en},
	urldate = {2022-06-27},
	journal = {Forest Ecology and Management},
	author = {Kauppi, Pekka E. and Stål, Gustav and Arnesson-Ceder, Lina and Hallberg Sramek, Isabella and Hoen, Hans Fredrik and Svensson, Arvid and Wernick, Iddo K. and Högberg, Peter and Lundmark, Tomas and Nordin, Annika},
	month = jun,
	year = {2022},
	keywords = {Boreal forests, Carbon cycle, Carbon mitigation, Forest ecosystems, Forest management, Global forests},
	pages = {120186},
}

Planting new forests has received scientific and political attention as a measure to mitigate climate change. Large, new forests have been planted in places like China and Ethiopia and, over time, a billion hectares could become available globally for planting new forests. Sustainable management of forests, which are available to wood production, has received less attention despite these forests covering at least two billion hectares globally. Better management of existing forests would improve forest growth and help mitigate climate change by increasing the forest carbon (C) stock, by storing C in forest products, and by generating wood-based materials substituting fossil C based materials or other CO2-emission-intensive materials. Some published research assumes a trade-off between the timber harvested from existing forests and the stock of C in those forest ecosystems, asserting that both cannot increase simultaneously. We tested this assumption using the uniquely detailed forest inventory data available from Finland, Norway and Sweden, hereafter denoted northern Europe. We focused on the period 1960 – 2017, that saw little change in the total area covered by forests in northern Europe. At the start of the period, rotational forestry practices began to diffuse, eventually replacing selective felling management systems as the most common management practice. Looking at data over the period we find that despite significant increases in timber and pulp wood harvests, the growth of the forest C stock accelerated. Over the study period, the C stock of the forest ecosystems in northern Europe increased by nearly 70%, while annual timber harvests increased at the about 40% over the same period. This increase in the forest C stock was close to on par with the CO2-emissions from the region (other greenhouse gases not included). Our results suggest that the important effects of management on forest growth allows the forest C stock and timber harvests to increase simultaneously. The development in northern Europe raises the question of how better forest management can improve forest growth elsewhere around the globe while at the same time protecting biodiversity and preserving landscapes.

@article{blasko_carbon_2022,
	title = {The carbon sequestration response of aboveground biomass and soils to nutrient enrichment in boreal forests depends on baseline site productivity},
	volume = {838},
	issn = {0048-9697},
	url = {https://www.sciencedirect.com/science/article/pii/S0048969722034246},
	doi = {10.1016/j.scitotenv.2022.156327},
	abstract = {Nutrient enrichment can alleviate productivity limitations and thus substantially increase carbon (C) uptake in northern coniferous forests. Yet, factors controlling stand-to-stand variation of forest ecosystem responses to nutrient enrichment remain unclear. We used five long-term (13 years) nutrient-enrichment experiments across Sweden, where nitrogen (N), phosphorus, and potassium were applied annually to young Norway spruce forests that varied in their baseline ecosystem properties. We measured tree biomass and soil C and N stocks, litterfall C inputs, soil CO2 efflux, and shifts in composition and biomass of soil microbial communities to understand the links between above and belowground responses to nutrient enrichment. We found that the strongest responses in tree biomass occurred when baseline site productivity was lowest. High increases in tree biomass C stocks were generally balanced by weaker responses in organic soil C stocks. The average ecosystem C–N response rate was 35 kg C kg−1 N added, with a nearly five-fold greater response rate in tree biomass than in soil. The positive nutrient enrichment effects on ecosystem C sinks were driven by a 95\% increase in tree biomass C stocks, 150\% increase in litter production, 67\% increase in organic layer C stocks, and a 46\% reduction in soil CO2 efflux accompanied by compositional changes in soil microbial communities. Our results show that ecosystem C uptake in spruce forests in northern Europe can be substantially enhanced by nutrient enrichment; however, the strength of the responses and whether the enhancement occurs mainly in tree biomass or soils are dependent on baseline forest productivity.},
	language = {en},
	urldate = {2022-06-30},
	journal = {Science of The Total Environment},
	author = {Blaško, Róbert and Forsmark, Benjamin and Gundale, Michael J. and Lim, Hyungwoo and Lundmark, Tomas and Nordin, Annika},
	month = sep,
	year = {2022},
	keywords = {Ecosystem carbon stocks, Litterfall, Soil carbon, Soil microbial community, Soil nitrogen, Soil respiration},
	pages = {156327},
}

Nutrient enrichment can alleviate productivity limitations and thus substantially increase carbon (C) uptake in northern coniferous forests. Yet, factors controlling stand-to-stand variation of forest ecosystem responses to nutrient enrichment remain unclear. We used five long-term (13 years) nutrient-enrichment experiments across Sweden, where nitrogen (N), phosphorus, and potassium were applied annually to young Norway spruce forests that varied in their baseline ecosystem properties. We measured tree biomass and soil C and N stocks, litterfall C inputs, soil CO2 efflux, and shifts in composition and biomass of soil microbial communities to understand the links between above and belowground responses to nutrient enrichment. We found that the strongest responses in tree biomass occurred when baseline site productivity was lowest. High increases in tree biomass C stocks were generally balanced by weaker responses in organic soil C stocks. The average ecosystem C–N response rate was 35 kg C kg−1 N added, with a nearly five-fold greater response rate in tree biomass than in soil. The positive nutrient enrichment effects on ecosystem C sinks were driven by a 95% increase in tree biomass C stocks, 150% increase in litter production, 67% increase in organic layer C stocks, and a 46% reduction in soil CO2 efflux accompanied by compositional changes in soil microbial communities. Our results show that ecosystem C uptake in spruce forests in northern Europe can be substantially enhanced by nutrient enrichment; however, the strength of the responses and whether the enhancement occurs mainly in tree biomass or soils are dependent on baseline forest productivity.

@article{forsmark_anthropogenic_2021,
	title = {Anthropogenic nitrogen enrichment increased the efficiency of belowground biomass production in a boreal forest},
	volume = {155},
	issn = {00380717},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0038071721000262},
	doi = {10/gjdqgb},
	language = {en},
	urldate = {2021-06-03},
	journal = {Soil Biology and Biochemistry},
	author = {Forsmark, Benjamin and Nordin, Annika and Rosenstock, Nicholas P. and Wallander, Håkan and Gundale, Michael J.},
	month = apr,
	year = {2021},
	pages = {108154},
}

@article{lutter_belowground_2021,
	title = {Belowground resource utilization in monocultures and mixtures of {Scots} pine and {Norway} spruce},
	volume = {500},
	issn = {0378-1127},
	url = {https://www.sciencedirect.com/science/article/pii/S0378112721007374},
	doi = {10.1016/j.foreco.2021.119647},
	abstract = {Mixed forests have been recommended to replace monocultures, often being more productive and resilient ecosystems. Those benefits of species mixing have been suggested to be attributed to lower competition (above- and belowground) due to potential separation of resource acquisition strategies, yet a mechanistic understanding of belowground processes has largely been missing. We applied an isotopic-labelling technique using 15N and 2H at {\textasciitilde}5 cm soil depth to study acquisition of two important resources, nitrogen (N) and water, in a replicated field experiment including mature Scots pine and Norway spruce monocultures and their mixture in boreal Sweden. Based on the isotopic data, we modelled distance-dependent N and water uptake and described the horizontal reach of active rooting areas around trees. The active root area for both N and water uptake in monocultures of both species was approximately 6–10 m2. Substantially wider areas were observed inside the mixture for N acquisition (27 m2 for pine and 21 m2 for spruce). Water was mainly acquired from within a 12–15 m2 area in mixture. The mixture and the pine monocultures exhibited similar recovery of the added 15N (3.8–4.5\%) and its uptake per unit of foliage mass. The recovery of 15N for the spruce monocultures was generally lower (2.1\%) but no difference was noted in the uptake per unit of foliage mass between spruce monoculture and mixture. No differences were found for recovery of 2H between the stand types. Mixing pine and spruce did not improve the resource uptake in comparison with the estimated theoretical mixture (according to the normalized basal area in monocultures). However, the mixing revealed significant differences between tree species whereas pines inside the mixture recovered 11.3-fold more 15N than accompanying spruce. Root overlap of 3–11 trees on 1 m2 was observed in all stand types, far exceeding the degree of canopy overlap. We discuss this overlap in terms of competition between individual trees. Spruces have proportionally larger horizontal rooting area relative to their aboveground size than pines. Scots pine and Norway spruce mixing in this type of boreal forest does not significantly enhance resource acquisition but leads to compensatory partitioning of growth, suggesting fierce interspecific competition, rather than niche separation.},
	language = {en},
	urldate = {2021-10-14},
	journal = {Forest Ecology and Management},
	author = {Lutter, Reimo and Henriksson, Nils and Lim, Hyungwoo and Blaško, Róbert and Magh, Ruth-Kristina and Näsholm, Torgny and Nordin, Annika and Lundmark, Tomas and Marshall, John D.},
	month = nov,
	year = {2021},
	keywords = {Mixed forests, Nitrogen, Root competition, Stable Isotopes, Water},
	pages = {119647},
}

Mixed forests have been recommended to replace monocultures, often being more productive and resilient ecosystems. Those benefits of species mixing have been suggested to be attributed to lower competition (above- and belowground) due to potential separation of resource acquisition strategies, yet a mechanistic understanding of belowground processes has largely been missing. We applied an isotopic-labelling technique using 15N and 2H at ~5 cm soil depth to study acquisition of two important resources, nitrogen (N) and water, in a replicated field experiment including mature Scots pine and Norway spruce monocultures and their mixture in boreal Sweden. Based on the isotopic data, we modelled distance-dependent N and water uptake and described the horizontal reach of active rooting areas around trees. The active root area for both N and water uptake in monocultures of both species was approximately 6–10 m2. Substantially wider areas were observed inside the mixture for N acquisition (27 m2 for pine and 21 m2 for spruce). Water was mainly acquired from within a 12–15 m2 area in mixture. The mixture and the pine monocultures exhibited similar recovery of the added 15N (3.8–4.5%) and its uptake per unit of foliage mass. The recovery of 15N for the spruce monocultures was generally lower (2.1%) but no difference was noted in the uptake per unit of foliage mass between spruce monoculture and mixture. No differences were found for recovery of 2H between the stand types. Mixing pine and spruce did not improve the resource uptake in comparison with the estimated theoretical mixture (according to the normalized basal area in monocultures). However, the mixing revealed significant differences between tree species whereas pines inside the mixture recovered 11.3-fold more 15N than accompanying spruce. Root overlap of 3–11 trees on 1 m2 was observed in all stand types, far exceeding the degree of canopy overlap. We discuss this overlap in terms of competition between individual trees. Spruces have proportionally larger horizontal rooting area relative to their aboveground size than pines. Scots pine and Norway spruce mixing in this type of boreal forest does not significantly enhance resource acquisition but leads to compensatory partitioning of growth, suggesting fierce interspecific competition, rather than niche separation.

@article{lutter_climate_2021,
	title = {Climate {Benefit} of {Different} {Tree} {Species} on {Former} {Agricultural} {Land} in {Northern} {Europe}},
	volume = {12},
	url = {https://www.mdpi.com/1999-4907/12/12/1810},
	doi = {10/gn64qp},
	abstract = {The new European Union Forest Strategy for 2030 aims to plant an additional 3 billion trees on non-forest land to mitigate climate change. However, the choice of tree species for afforestation to achieve the maximum climate benefit is unclear. We compared the climate benefit of six different species in terms of carbon (C) sequestration in biomass and the harvested wood substitution in products to avoid carbon dioxide (CO2) emissions from fossil-based materials over the 100-year period by afforesting about \¼ of the available area in northern Europe. The highest climate benefit was observed for larch, both at a stand scale (1626 Mg CO2 eqv. ha\−1) and at the landscape level for the studied scenario (579 million Mg CO2 eqv.). Larch was followed by Norway spruce, poplar, hybrid aspen and birch, showing a climate benefit about 40\–50\% lower than that for larch. The climate benefit of willow was about 70\% lower than larch. Willow showed 6\–14-fold lower C stocks at the landscape level after 100 years than other tree species. The major climate benefit over the 100-year period comes from wood substitution and avoided emissions, but C stock buildup at the landscape level also removes significant amounts of CO2 already present in the atmosphere. The choice of tree species is important to maximize climate change mitigation.},
	language = {en},
	number = {12},
	urldate = {2022-01-17},
	journal = {Forests},
	author = {Lutter, Reimo and Stål, Gustav and Arnesson Ceder, Lina and Lim, Hyungwoo and Padari, Allar and Tullus, Hardi and Nordin, Annika and Lundmark, Tomas},
	month = dec,
	year = {2021},
	keywords = {Norway spruce, carbon substitution, climate change, forest carbon, hybrid aspen, larch, poplar, silver birch, willow},
	pages = {1810},
}

The new European Union Forest Strategy for 2030 aims to plant an additional 3 billion trees on non-forest land to mitigate climate change. However, the choice of tree species for afforestation to achieve the maximum climate benefit is unclear. We compared the climate benefit of six different species in terms of carbon (C) sequestration in biomass and the harvested wood substitution in products to avoid carbon dioxide (CO2) emissions from fossil-based materials over the 100-year period by afforesting about ¼ of the available area in northern Europe. The highest climate benefit was observed for larch, both at a stand scale (1626 Mg CO2 eqv. ha−1) and at the landscape level for the studied scenario (579 million Mg CO2 eqv.). Larch was followed by Norway spruce, poplar, hybrid aspen and birch, showing a climate benefit about 40–50% lower than that for larch. The climate benefit of willow was about 70% lower than larch. Willow showed 6–14-fold lower C stocks at the landscape level after 100 years than other tree species. The major climate benefit over the 100-year period comes from wood substitution and avoided emissions, but C stock buildup at the landscape level also removes significant amounts of CO2 already present in the atmosphere. The choice of tree species is important to maximize climate change mitigation.

@article{van_sundert_increased_2021,
	title = {Increased tree growth following long-term optimised fertiliser application indirectly alters soil properties in a boreal forest},
	volume = {140},
	issn = {1612-4677},
	url = {https://doi.org/10.1007/s10342-020-01327-y},
	doi = {10.1007/s10342-020-01327-y},
	abstract = {It is well established that nutrient addition influences ecosystem features such as productivity, carbon storage, soil acidification and biodiversity. Less studied are long-term effects of sustained fertiliser application on forest soil characteristics and nutrient supplies, and especially direct and indirect mechanisms underlying changes. We investigated effects of 3 decades versus 1 decade of optimised fertiliser application on soil properties and nutrient supplies in a 30-year-old nutrient optimisation experiment in a Norway spruce plantation in northern Sweden. We tested for direct and indirect effects of fertiliser use through structural equation models and correlations among tree and soil variables. Results showed that soil characteristics, especially organic carbon and nutrient concentrations, were significantly affected by 10- and 30-year fertiliser application. Soil C/N was similar for the short-term versus controls, but decreased for the long-term versus short-term treatment. Although not explicitly measured, it was clear from our analyses and earlier studies at the site that litter accumulation played a key role in explaining these changes in soil properties, while foliar stoichiometry data suggest long-term effects of litter quality. Nutrient supply rates increased more after 30 than 10 years of fertiliser application. Summarized, we showed that the interplay of direct and indirect effects can yield nonlinear patterns over time, as exemplified by soil C/N. Furthermore, we conclude that lagged, indirect effects of fertilisation through altered litter quantity and quality dominate changes in soil characteristics in this forest. These soil characteristics have further relevance to nutrient availability, suggesting that nutrient optimisation can influence soil fertility also indirectly.},
	language = {en},
	number = {1},
	urldate = {2021-06-07},
	journal = {European Journal of Forest Research},
	author = {Van Sundert, Kevin and Linder, Sune and Marshall, John D. and Nordin, Annika and Vicca, Sara},
	month = feb,
	year = {2021},
	pages = {241--254},
}

It is well established that nutrient addition influences ecosystem features such as productivity, carbon storage, soil acidification and biodiversity. Less studied are long-term effects of sustained fertiliser application on forest soil characteristics and nutrient supplies, and especially direct and indirect mechanisms underlying changes. We investigated effects of 3 decades versus 1 decade of optimised fertiliser application on soil properties and nutrient supplies in a 30-year-old nutrient optimisation experiment in a Norway spruce plantation in northern Sweden. We tested for direct and indirect effects of fertiliser use through structural equation models and correlations among tree and soil variables. Results showed that soil characteristics, especially organic carbon and nutrient concentrations, were significantly affected by 10- and 30-year fertiliser application. Soil C/N was similar for the short-term versus controls, but decreased for the long-term versus short-term treatment. Although not explicitly measured, it was clear from our analyses and earlier studies at the site that litter accumulation played a key role in explaining these changes in soil properties, while foliar stoichiometry data suggest long-term effects of litter quality. Nutrient supply rates increased more after 30 than 10 years of fertiliser application. Summarized, we showed that the interplay of direct and indirect effects can yield nonlinear patterns over time, as exemplified by soil C/N. Furthermore, we conclude that lagged, indirect effects of fertilisation through altered litter quantity and quality dominate changes in soil characteristics in this forest. These soil characteristics have further relevance to nutrient availability, suggesting that nutrient optimisation can influence soil fertility also indirectly.

@article{forsmark_longterm_2021,
	title = {Long‐term nitrogen enrichment does not increase microbial phosphorus mobilization in a northern coniferous forest},
	volume = {35},
	issn = {0269-8463, 1365-2435},
	url = {https://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13701},
	doi = {10.1111/1365-2435.13701},
	language = {en},
	number = {1},
	urldate = {2021-06-07},
	journal = {Functional Ecology},
	author = {Forsmark, Benjamin and Wallander, Håkan and Nordin, Annika and Gundale, Michael J.},
	editor = {Stevens, Carly},
	month = jan,
	year = {2021},
	pages = {277--287},
}

@article{maher_hasselquist_moving_2021,
	title = {Moving towards multi-layered, mixed-species forests in riparian buffers will enhance their long-term function in boreal landscapes},
	volume = {493},
	issn = {0378-1127},
	url = {https://www.sciencedirect.com/science/article/pii/S037811272100342X},
	doi = {10.1016/j.foreco.2021.119254},
	abstract = {Riparian buffers are the primary tool in forest management for protecting the habitat structure and function of streams. They help protect against biogeochemical perturbation, filter sediments and nutrients, prevent erosion, contribute food to aquatic organisms, regulate light and hence water temperature, contribute deadwood, and preserve biodiversity. However, in production forests of Sweden and Finland, many headwater streams have been straightened, ditched, and/or channelized, resulting in altered hydrology and reduced natural disturbance by floods, which in turn affects important riparian functions. Furthermore, in even-aged management systems as practiced in much of Fennoscandia, understory trees have usually been cleared right up to the stream’s edge during thinning operations, especially around small, headwater streams. Fire suppression has further favored succession towards shade tolerant species. In the regions within Fennoscandia that have experienced this combination of intensive management and lack of natural disturbance, riparian zones are now dominated by single-storied, native Norway spruce. When the adjacent forest is cut, thin (5 - 15m) conifer-dominated riparian buffers are typically left. These buffers do not provide the protection and subsidies, in terms of leaf litter quality, needed to maintain water quality or support riparian or aquatic biodiversity. Based on a literature review, we found compelling evidence that the ecological benefits of multi-layered, mixed-species riparian forest with a large component of broadleaved species are higher than what is now commonly found in the managed stands of Fennoscandia. To improve the functionality of riparian zones, and hence the protection of streams in managed forest landscapes, we present some basic principles that could be used to enhance the ecological function of these interfaces. These management actions should be prioritized on streams and streamside stands that have been affected by simplification either through forest management or hydrological modification. Key to these principles is the planning and managing of buffer zones as early as possible in the rotation to ensure improved function throughout the rotation cycle and not only at final felling. This is well in line with EU and national legislation which can be interpreted as requiring landscape planning at all forest ages to meet biodiversity and other environmental goals. However, it is still rare that planning for conservation is done other than at the final felling stage. Implementing this new strategy is likely to have long-term positive effects and improve the protection of surface waters from negative forestry effects and a history of fire suppression. By following these suggested management principles, there will be a longer time period with high function and greater future management flexibility in addition to the benefits provided by leaving riparian buffers at the final felling stage.},
	language = {en},
	urldate = {2021-06-17},
	journal = {Forest Ecology and Management},
	author = {Maher Hasselquist, Eliza and Kuglerová, Lenka and Sjögren, Jörgen and Hjältén, Joakim and Ring, Eva and Sponseller, Ryan A. and Andersson, Elisabet and Lundström, Johanna and Mancheva, Irina and Nordin, Annika and Laudon, Hjalmar},
	month = aug,
	year = {2021},
	keywords = {boreal, broadleaf, continuous cover forestry, deciduous, forest planning, retention forestry, uneven-aged forestry},
	pages = {119254},
}

Riparian buffers are the primary tool in forest management for protecting the habitat structure and function of streams. They help protect against biogeochemical perturbation, filter sediments and nutrients, prevent erosion, contribute food to aquatic organisms, regulate light and hence water temperature, contribute deadwood, and preserve biodiversity. However, in production forests of Sweden and Finland, many headwater streams have been straightened, ditched, and/or channelized, resulting in altered hydrology and reduced natural disturbance by floods, which in turn affects important riparian functions. Furthermore, in even-aged management systems as practiced in much of Fennoscandia, understory trees have usually been cleared right up to the stream’s edge during thinning operations, especially around small, headwater streams. Fire suppression has further favored succession towards shade tolerant species. In the regions within Fennoscandia that have experienced this combination of intensive management and lack of natural disturbance, riparian zones are now dominated by single-storied, native Norway spruce. When the adjacent forest is cut, thin (5 - 15m) conifer-dominated riparian buffers are typically left. These buffers do not provide the protection and subsidies, in terms of leaf litter quality, needed to maintain water quality or support riparian or aquatic biodiversity. Based on a literature review, we found compelling evidence that the ecological benefits of multi-layered, mixed-species riparian forest with a large component of broadleaved species are higher than what is now commonly found in the managed stands of Fennoscandia. To improve the functionality of riparian zones, and hence the protection of streams in managed forest landscapes, we present some basic principles that could be used to enhance the ecological function of these interfaces. These management actions should be prioritized on streams and streamside stands that have been affected by simplification either through forest management or hydrological modification. Key to these principles is the planning and managing of buffer zones as early as possible in the rotation to ensure improved function throughout the rotation cycle and not only at final felling. This is well in line with EU and national legislation which can be interpreted as requiring landscape planning at all forest ages to meet biodiversity and other environmental goals. However, it is still rare that planning for conservation is done other than at the final felling stage. Implementing this new strategy is likely to have long-term positive effects and improve the protection of surface waters from negative forestry effects and a history of fire suppression. By following these suggested management principles, there will be a longer time period with high function and greater future management flexibility in addition to the benefits provided by leaving riparian buffers at the final felling stage.

@article{haggstrom_survival_2021,
	title = {Survival and growth of {Scots} pine ({Pinus} sylvestris) seedlings in north {Sweden}: effects of planting position and arginine phosphate addition},
	volume = {0},
	issn = {0282-7581},
	shorttitle = {Survival and growth of {Scots} pine ({Pinus} sylvestris) seedlings in north {Sweden}},
	url = {https://doi.org/10.1080/02827581.2021.1957999},
	doi = {10/gmhq68},
	abstract = {Forest regeneration by tree planting on harvested sites in the boreal forests of northern Europe is frequently preceded by site preparation to increase survival and growth of the seedlings. We studied whether a small addition of arginine phosphate (AP treatment) at the time of planting would further enhance the seedlings’ early performance. Following two growth seasons, we investigated survival and growth of Scots pine (Pinus sylvestris) seedlings on 11 locations between latitudes 61.1°N and 67.1°N in the boreal forest of northern Sweden. The planting positions of seedlings were on capped mounds and bare mineral soil following mechanical site preparation, and in non-prepared soil. We found that seedling survival following site preparation increased with AP treatment. On capped mounds, seedling survival was more variable and appeared more dependent on precipitation during the first month after planting than seedlings positioned in the mineral soil. The positive effect of AP treatment on seedling growth differed between sites and was more pronounced on sites with longer growing seasons. AP treatment had no significant effect on survival of seedlings planted in non-prepared soil, while the positive effect on growth was more pronounced at sites with higher fertility using this planting position.},
	number = {0},
	urldate = {2021-08-18},
	journal = {Scandinavian Journal of Forest Research},
	author = {Häggström, Bodil and Domevscik, Matej and Öhlund, Jonas and Nordin, Annika},
	month = jul,
	year = {2021},
	keywords = {Pinus sylvestris, arginine phosphate, conifer plantations, cultivation, damage, establishment, fertilization, forest regeneration, norway spruce, organic nitrogen, performance, picea-abies, planting positions, seedling   growth, seedling growth, seedling survival, site preparation},
	pages = {1--11},
}

Forest regeneration by tree planting on harvested sites in the boreal forests of northern Europe is frequently preceded by site preparation to increase survival and growth of the seedlings. We studied whether a small addition of arginine phosphate (AP treatment) at the time of planting would further enhance the seedlings’ early performance. Following two growth seasons, we investigated survival and growth of Scots pine (Pinus sylvestris) seedlings on 11 locations between latitudes 61.1°N and 67.1°N in the boreal forest of northern Sweden. The planting positions of seedlings were on capped mounds and bare mineral soil following mechanical site preparation, and in non-prepared soil. We found that seedling survival following site preparation increased with AP treatment. On capped mounds, seedling survival was more variable and appeared more dependent on precipitation during the first month after planting than seedlings positioned in the mineral soil. The positive effect of AP treatment on seedling growth differed between sites and was more pronounced on sites with longer growing seasons. AP treatment had no significant effect on survival of seedlings planted in non-prepared soil, while the positive effect on growth was more pronounced at sites with higher fertility using this planting position.

@article{kauppi_carbon_2020,
	title = {Carbon benefits from {Forest} {Transitions} promoting biomass expansions and thickening},
	volume = {26},
	issn = {1354-1013, 1365-2486},
	url = {https://onlinelibrary.wiley.com/doi/10.1111/gcb.15292},
	doi = {10.1111/gcb.15292},
	language = {en},
	number = {10},
	urldate = {2021-06-07},
	journal = {Global Change Biology},
	author = {Kauppi, Pekka E. and Ciais, Philippe and Högberg, Peter and Nordin, Annika and Lappi, Juha and Lundmark, Tomas and Wernick, Iddo K.},
	month = oct,
	year = {2020},
	pages = {5365--5370},
}

@article{lim_effects_2020,
	title = {Effects of whole‐tree harvesting at thinning and subsequent compensatory nutrient additions on carbon sequestration and soil acidification in a boreal forest},
	volume = {12},
	issn = {1757-1693, 1757-1707},
	url = {https://onlinelibrary.wiley.com/doi/10.1111/gcbb.12737},
	doi = {10.1111/gcbb.12737},
	language = {en},
	number = {11},
	urldate = {2021-06-07},
	journal = {GCB Bioenergy},
	author = {Lim, Hyungwoo and Olsson, Bengt A. and Lundmark, Tomas and Dahl, Jenny and Nordin, Annika},
	month = nov,
	year = {2020},
	pages = {992--1001},
}

@article{hallberg-sramek_framing_2020,
	title = {Framing woodland key habitats in the {Swedish} media – how has the framing changed over time?},
	volume = {35},
	issn = {0282-7581, 1651-1891},
	url = {https://www.tandfonline.com/doi/full/10.1080/02827581.2020.1761444},
	doi = {10.1080/02827581.2020.1761444},
	language = {en},
	number = {3-4},
	urldate = {2021-06-07},
	journal = {Scandinavian Journal of Forest Research},
	author = {Hallberg-Sramek, Isabella and Bjärstig, Therese and Nordin, Annika},
	month = may,
	year = {2020},
	pages = {198--209},
}

@article{blasko_impacts_2020,
	title = {Impacts of tree species identity and species mixing on ecosystem carbon and nitrogen stocks in a boreal forest},
	volume = {458},
	issn = {03781127},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0378112719319607},
	doi = {10.1016/j.foreco.2019.117783},
	language = {en},
	urldate = {2021-06-07},
	journal = {Forest Ecology and Management},
	author = {Blaško, Róbert and Forsmark, Benjamin and Gundale, Michael J. and Lundmark, Tomas and Nordin, Annika},
	month = feb,
	year = {2020},
	pages = {117783},
}

@article{forsmark_low_2020,
	title = {Low and {High} {Nitrogen} {Deposition} {Rates} in {Northern} {Coniferous} {Forests} {Have} {Different} {Impacts} on {Aboveground} {Litter} {Production}, {Soil} {Respiration}, and {Soil} {Carbon} {Stocks}},
	volume = {23},
	issn = {1432-9840, 1435-0629},
	url = {http://link.springer.com/10.1007/s10021-020-00478-8},
	doi = {10/gjcvpf},
	abstract = {Abstract
            
              Nitrogen (N) deposition can change the carbon (C) sink of northern coniferous forests by changing the balance between net primary production and soil respiration. We used a field experiment in an N poor
              Pinus sylvestris
              forest where five levels of N (0, 3, 6, 12, and 50 kg N ha
              −1
               yr
              −1
              ,
              n
               = 6) had been added annually for 12–13 years to investigate how litter C inputs and soil respiration, divided into its autotrophic and heterotrophic sources, respond to different rates of N input, and its subsequent effect on soil C storage. The highest N addition rate (50 kg N ha
              −1
               yr
              −1
              ) stimulated soil C accumulation in the organic layer by 22.3 kg C kg
              −1
               N added, increased litter inputs by 46\%, and decreased soil respiration per mass unit of soil C by 31.2\%, mainly by decreasing autotrophic respiration. Lower N addition rates (≤ 12 kg N ha
              −1
               yr
              −1
              ) had no effect on litter inputs or soil respiration. These results support previous studies reporting on increased litter inputs coupled to impeded soil C mineralization, contributing to enhancing the soil C sink when N is supplied at high rates, but add observations for lower N addition rates more realistic for N deposition. In doing so, we show that litter production in N poor northern coniferous forests can be relatively unresponsive to low N deposition levels, that stimulation of microbial activity at low N additions is unlikely to reduce the soil C sink, and that high levels of N deposition enhance the soil C sink by increasing litter inputs and decreasing soil respiration.},
	language = {en},
	number = {7},
	urldate = {2021-06-07},
	journal = {Ecosystems},
	author = {Forsmark, Benjamin and Nordin, Annika and Maaroufi, Nadia I. and Lundmark, Tomas and Gundale, Michael J.},
	month = nov,
	year = {2020},
	pages = {1423--1436},
}

Abstract Nitrogen (N) deposition can change the carbon (C) sink of northern coniferous forests by changing the balance between net primary production and soil respiration. We used a field experiment in an N poor Pinus sylvestris forest where five levels of N (0, 3, 6, 12, and 50 kg N ha −1  yr −1 , n  = 6) had been added annually for 12–13 years to investigate how litter C inputs and soil respiration, divided into its autotrophic and heterotrophic sources, respond to different rates of N input, and its subsequent effect on soil C storage. The highest N addition rate (50 kg N ha −1  yr −1 ) stimulated soil C accumulation in the organic layer by 22.3 kg C kg −1  N added, increased litter inputs by 46%, and decreased soil respiration per mass unit of soil C by 31.2%, mainly by decreasing autotrophic respiration. Lower N addition rates (≤ 12 kg N ha −1  yr −1 ) had no effect on litter inputs or soil respiration. These results support previous studies reporting on increased litter inputs coupled to impeded soil C mineralization, contributing to enhancing the soil C sink when N is supplied at high rates, but add observations for lower N addition rates more realistic for N deposition. In doing so, we show that litter production in N poor northern coniferous forests can be relatively unresponsive to low N deposition levels, that stimulation of microbial activity at low N additions is unlikely to reduce the soil C sink, and that high levels of N deposition enhance the soil C sink by increasing litter inputs and decreasing soil respiration.

@article{sandstrom_policy_2020,
	title = {Policy goals and instruments for achieving a desirable future forest: {Experiences} from backcasting with stakeholders in {Sweden}},
	volume = {111},
	issn = {13899341},
	shorttitle = {Policy goals and instruments for achieving a desirable future forest},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S1389934119300012},
	doi = {10.1016/j.forpol.2019.102051},
	language = {en},
	urldate = {2021-06-07},
	journal = {Forest Policy and Economics},
	author = {Sandström, Camilla and Kanyama, Annika Carlsson and Räty, Riitta and Sonnek, Karin Mossberg and Nordström, Eva-Maria and Mossing, Annika and Nordin, Annika},
	month = feb,
	year = {2020},
	pages = {102051},
}

@article{bjarstig_struggling_2019,
	title = {A struggling collaborative process – revisiting the woodland key habitat concept in {Swedish} forests},
	volume = {34},
	issn = {0282-7581, 1651-1891},
	url = {https://www.tandfonline.com/doi/full/10.1080/02827581.2019.1674916},
	doi = {10.1080/02827581.2019.1674916},
	language = {en},
	number = {8},
	urldate = {2021-06-07},
	journal = {Scandinavian Journal of Forest Research},
	author = {Bjärstig, Therese and Sandström, Camilla and Sjögren, Jörgen and Soneson, Johan and Nordin, Annika},
	month = nov,
	year = {2019},
	pages = {699--708},
}

@article{maaroufi_anthropogenic_2019,
	title = {Anthropogenic nitrogen enrichment enhances soil carbon accumulation by impacting saprotrophs rather than ectomycorrhizal fungal activity},
	volume = {25},
	issn = {1354-1013, 1365-2486},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14722},
	doi = {10/ghmmzn},
	language = {en},
	number = {9},
	urldate = {2021-06-07},
	journal = {Global Change Biology},
	author = {Maaroufi, Nadia I. and Nordin, Annika and Palmqvist, Kristin and Hasselquist, Niles J. and Forsmark, Benjamin and Rosenstock, Nicholas P. and Wallander, Håkan and Gundale, Michael J.},
	month = sep,
	year = {2019},
	pages = {2900--2914},
}

@article{stens_ecological_2019,
	title = {From ecological knowledge to conservation policy: a case study on green tree retention and continuous-cover forestry in {Sweden}},
	volume = {28},
	issn = {0960-3115, 1572-9710},
	shorttitle = {From ecological knowledge to conservation policy},
	url = {http://link.springer.com/10.1007/s10531-019-01836-2},
	doi = {10.1007/s10531-019-01836-2},
	language = {en},
	number = {13},
	urldate = {2021-06-07},
	journal = {Biodiversity and Conservation},
	author = {Sténs, Anna and Roberge, Jean-Michel and Löfmarck, Erik and Beland Lindahl, Karin and Felton, Adam and Widmark, Camilla and Rist, Lucy and Johansson, Johanna and Nordin, Annika and Nilsson, Urban and Laudon, Hjalmar and Ranius, Thomas},
	month = nov,
	year = {2019},
	pages = {3547--3574},
}

@article{palmroth_nitrogen_2019,
	title = {Nitrogen supply and other controls of carbon uptake of understory vegetation in a boreal {Picea} abies forest},
	volume = {276-277},
	issn = {01681923},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S016819231930228X},
	doi = {10.1016/j.agrformet.2019.107620},
	language = {en},
	urldate = {2021-06-07},
	journal = {Agricultural and Forest Meteorology},
	author = {Palmroth, Sari and Bach, Lisbet H. and Lindh, Marie and Kolari, Pasi and Nordin, Annika and Palmqvist, Kristin},
	month = oct,
	year = {2019},
	pages = {107620},
}

@article{klapwijk_capturing_2018,
	title = {Capturing complexity: {Forests}, decision-making and climate change mitigation action},
	volume = {52},
	issn = {09593780},
	shorttitle = {Capturing complexity},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0959378017312815},
	doi = {10.1016/j.gloenvcha.2018.07.012},
	language = {en},
	urldate = {2021-06-07},
	journal = {Global Environmental Change},
	author = {Klapwijk, M.J. and Boberg, J. and Bergh, J. and Bishop, K. and Björkman, C. and Ellison, D. and Felton, A. and Lidskog, R. and Lundmark, T. and Keskitalo, E.C.H. and Sonesson, J. and Nordin, A. and Nordström, E.-M. and Stenlid, J. and Mårald, E.},
	month = sep,
	year = {2018},
	pages = {238--247},
}

@article{lundmark_carbon_2018,
	title = {Carbon balance in production forestry in relation to rotation length},
	volume = {48},
	issn = {0045-5067, 1208-6037},
	url = {http://www.nrcresearchpress.com/doi/10.1139/cjfr-2017-0410},
	doi = {10.1139/cjfr-2017-0410},
	abstract = {The choice of a rotation length is an integral part of even-aged forest management regimes. In this study, we simulated stand development and carbon pools in four even-aged stands representing the two most common tree species in Fennoscandia, Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.), growing on high- and low-productivity sites. We hypothesized that increased rotation lengths (+10, +20, and +30 years) in comparison with today’s practice would increase forests’ average carbon stock during a rotation cycle but decrease the average yield. The results showed that for spruce, a moderate increase in rotation length (+10 years) increased both average standing carbon stock and average yield. For the longer alternatives (+20 and +30 years) for spruce and for all pine alternatives, prolonging rotation lengths resulted in increased average standing carbon stocks but decreased average yield, resulting in decreased carbon storage in forest products and decreased substitution effects. Decreasing the rotation lengths (–10 years) always resulted in both decreased average standing carbon stocks and decreased yields. We conclude that a moderate increase of rotation lengths may slightly increase forests’ climate benefits for spruce sites, but for all other alternatives, there was a trade-off between the temporary gain of increasing carbon stocks and the permanent loss in productivity and, consequently, substitution potential.},
	language = {en},
	number = {6},
	urldate = {2021-06-07},
	journal = {Canadian Journal of Forest Research},
	author = {Lundmark, Tomas and Poudel, Bishnu Chandra and Stål, Gustav and Nordin, Annika and Sonesson, Johan},
	month = jun,
	year = {2018},
	pages = {672--678},
}

The choice of a rotation length is an integral part of even-aged forest management regimes. In this study, we simulated stand development and carbon pools in four even-aged stands representing the two most common tree species in Fennoscandia, Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.), growing on high- and low-productivity sites. We hypothesized that increased rotation lengths (+10, +20, and +30 years) in comparison with today’s practice would increase forests’ average carbon stock during a rotation cycle but decrease the average yield. The results showed that for spruce, a moderate increase in rotation length (+10 years) increased both average standing carbon stock and average yield. For the longer alternatives (+20 and +30 years) for spruce and for all pine alternatives, prolonging rotation lengths resulted in increased average standing carbon stocks but decreased average yield, resulting in decreased carbon storage in forest products and decreased substitution effects. Decreasing the rotation lengths (–10 years) always resulted in both decreased average standing carbon stocks and decreased yields. We conclude that a moderate increase of rotation lengths may slightly increase forests’ climate benefits for spruce sites, but for all other alternatives, there was a trade-off between the temporary gain of increasing carbon stocks and the permanent loss in productivity and, consequently, substitution potential.

@article{horn_growth_2018,
	title = {Growth and survival relationships of 71 tree species with nitrogen and sulfur deposition across the conterminous {U}.{S}.},
	volume = {13},
	issn = {1932-6203},
	url = {https://dx.plos.org/10.1371/journal.pone.0205296},
	doi = {10.1371/journal.pone.0205296},
	language = {en},
	number = {10},
	urldate = {2021-06-07},
	journal = {PLOS ONE},
	author = {Horn, Kevin J. and Thomas, R. Quinn and Clark, Christopher M. and Pardo, Linda H. and Fenn, Mark E. and Lawrence, Gregory B. and Perakis, Steven S. and Smithwick, Erica A. H. and Baldwin, Douglas and Braun, Sabine and Nordin, Annika and Perry, Charles H. and Phelan, Jennifer N. and Schaberg, Paul G. and St. Clair, Samuel B. and Warby, Richard and Watmough, Shaun},
	editor = {Loustau, Denis},
	month = oct,
	year = {2018},
	pages = {e0205296},
}

@article{hedwall_interplay_2018,
	title = {Interplay between {N}-form and {N}-dose influences ecosystem effects of {N} addition to boreal forest},
	volume = {423},
	issn = {0032-079X, 1573-5036},
	url = {http://link.springer.com/10.1007/s11104-017-3444-1},
	doi = {10.1007/s11104-017-3444-1},
	language = {en},
	number = {1-2},
	urldate = {2021-06-07},
	journal = {Plant and Soil},
	author = {Hedwall, Per-Ola and Gruffman, Linda and Ishida, Takahide and From, Fredrik and Lundmark, Tomas and Näsholm, Torgny and Nordin, Annika},
	month = feb,
	year = {2018},
	pages = {385--395},
}

@article{roberge_modified_2018,
	title = {Modified forest rotation lengths: {Long}-term effects on landscape-scale habitat availability for specialized species},
	volume = {210},
	issn = {03014797},
	shorttitle = {Modified forest rotation lengths},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0301479717311908},
	doi = {10/gc5jnj},
	language = {en},
	urldate = {2021-06-07},
	journal = {Journal of Environmental Management},
	author = {Roberge, Jean-Michel and Öhman, Karin and Lämås, Tomas and Felton, Adam and Ranius, Thomas and Lundmark, Tomas and Nordin, Annika},
	month = mar,
	year = {2018},
	pages = {1--9},
}

@article{maaroufi_nutrient_2018,
	title = {Nutrient optimization of tree growth alters structure and function of boreal soil food webs},
	volume = {428},
	issn = {03781127},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0378112718301142},
	doi = {10.1016/j.foreco.2018.06.034},
	language = {en},
	urldate = {2021-06-07},
	journal = {Forest Ecology and Management},
	author = {Maaroufi, Nadia I. and Palmqvist, Kristin and Bach, Lisbet H. and Bokhorst, Stef and Liess, Antonia and Gundale, Michael J. and Kardol, Paul and Nordin, Annika and Meunier, Cédric L.},
	month = nov,
	year = {2018},
	pages = {46--56},
}

@article{strengbom_trade-offs_2018,
	title = {Trade-offs in the multi-use potential of managed boreal forests},
	volume = {55},
	issn = {00218901},
	url = {http://doi.wiley.com/10.1111/1365-2664.13019},
	doi = {10/gc4hkp},
	language = {en},
	number = {2},
	urldate = {2021-06-07},
	journal = {Journal of Applied Ecology},
	author = {Strengbom, Joachim and Axelsson, E. Petter and Lundmark, Tomas and Nordin, Annika},
	editor = {Villard, Marc-André},
	month = mar,
	year = {2018},
	pages = {958--966},
}

@article{perring_understanding_2018,
	title = {Understanding context dependency in the response of forest understorey plant communities to nitrogen deposition},
	volume = {242},
	issn = {02697491},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0269749118316610},
	doi = {10.1016/j.envpol.2018.07.089},
	language = {en},
	urldate = {2021-06-07},
	journal = {Environmental Pollution},
	author = {Perring, Michael P. and Diekmann, Martin and Midolo, Gabriele and Schellenberger Costa, David and Bernhardt-Römermann, Markus and Otto, Johanna C.J. and Gilliam, Frank S. and Hedwall, Per-Ola and Nordin, Annika and Dirnböck, Thomas and Simkin, Samuel M. and Máliš, František and Blondeel, Haben and Brunet, Jörg and Chudomelová, Markéta and Durak, Tomasz and De Frenne, Pieter and Hédl, Radim and Kopecký, Martin and Landuyt, Dries and Li, Daijiang and Manning, Peter and Petřík, Petr and Reczyńska, Kamila and Schmidt, Wolfgang and Standovár, Tibor and Świerkosz, Krzysztof and Vild, Ondřej and Waller, Donald M. and Verheyen, Kris},
	month = nov,
	year = {2018},
	pages = {1787--1799},
}

@article{nummelin_forest_2017,
	title = {Forest future s by {Swedish} students – developing a mind mapping method for data collection},
	volume = {32},
	issn = {0282-7581, 1651-1891},
	url = {https://www.tandfonline.com/doi/full/10.1080/02827581.2017.1287303},
	doi = {10/gbv2r6},
	language = {en},
	number = {8},
	urldate = {2021-06-07},
	journal = {Scandinavian Journal of Forest Research},
	author = {Nummelin, Tuomas and Widmark, Camilla and Riala, Maria and Sténs, Anna and Nordström, Eva-Maria and Nordin, Annika},
	month = nov,
	year = {2017},
	pages = {807--817},
}

@article{maaroufi_nitrogen_2017,
	title = {Nitrogen enrichment impacts on boreal litter decomposition are driven by changes in soil microbiota rather than litter quality},
	volume = {7},
	issn = {2045-2322},
	url = {http://www.nature.com/articles/s41598-017-04523-w},
	doi = {10/gbnjm6},
	language = {en},
	number = {1},
	urldate = {2021-06-07},
	journal = {Scientific Reports},
	author = {Maaroufi, Nadia I. and Nordin, Annika and Palmqvist, Kristin and Gundale, Michael J.},
	month = dec,
	year = {2017},
	pages = {4083},
}

@article{cintas_potential_2017,
	title = {The potential role of forest management in {Swedish} scenarios towards climate neutrality by mid century},
	volume = {383},
	issn = {03781127},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0378112716303619},
	doi = {10.1016/j.foreco.2016.07.015},
	language = {en},
	urldate = {2021-06-07},
	journal = {Forest Ecology and Management},
	author = {Cintas, Olivia and Berndes, Göran and Hansson, Julia and Poudel, Bishnu Chandra and Bergh, Johan and Börjesson, Pål and Egnell, Gustaf and Lundmark, Tomas and Nordin, Annika},
	month = jan,
	year = {2017},
	pages = {73--84},
}

@article{maaroufi_chronic_2016,
	title = {Chronic {Nitrogen} {Deposition} {Has} a {Minor} {Effect} on the {Quantity} and {Quality} of {Aboveground} {Litter} in a {Boreal} {Forest}},
	volume = {11},
	issn = {1932-6203},
	url = {https://dx.plos.org/10.1371/journal.pone.0162086},
	doi = {10/f3tbg7},
	language = {en},
	number = {8},
	urldate = {2021-06-07},
	journal = {PLOS ONE},
	author = {Maaroufi, Nadia I. and Nordin, Annika and Palmqvist, Kristin and Gundale, Michael J.},
	editor = {BassiriRad, Hormoz},
	month = aug,
	year = {2016},
	pages = {e0162086},
}

@article{lundmark_comparison_2016,
	title = {Comparison of carbon balances between continuous-cover and clear-cut forestry in {Sweden}},
	volume = {45},
	issn = {0044-7447, 1654-7209},
	url = {http://link.springer.com/10.1007/s13280-015-0756-3},
	doi = {10.1007/s13280-015-0756-3},
	language = {en},
	number = {S2},
	urldate = {2021-06-07},
	journal = {Ambio},
	author = {Lundmark, Tomas and Bergh, Johan and Nordin, Annika and Fahlvik, Nils and Poudel, Bishnu Chandra},
	month = feb,
	year = {2016},
	pages = {203--213},
}

@article{from_effects_2016,
	title = {Effects of simulated long-term {N} deposition on \textit{{Picea} abies} and \textit{{Pinus} sylvestris} growth in boreal forest},
	volume = {46},
	issn = {0045-5067, 1208-6037},
	url = {http://www.nrcresearchpress.com/doi/10.1139/cjfr-2016-0201},
	doi = {10.1139/cjfr-2016-0201},
	language = {en},
	number = {11},
	urldate = {2021-06-07},
	journal = {Canadian Journal of Forest Research},
	author = {From, F. and Lundmark, T. and Mörling, T. and Pommerening, A. and Nordin, A.},
	month = nov,
	year = {2016},
	pages = {1396--1403},
}

@article{nordstrom_impacts_2016,
	title = {Impacts of global climate change mitigation scenarios on forests and harvesting in {Sweden}},
	volume = {46},
	issn = {0045-5067, 1208-6037},
	url = {http://www.nrcresearchpress.com/doi/10.1139/cjfr-2016-0122},
	doi = {10.1139/cjfr-2016-0122},
	abstract = {Under climate change, the importance of biomass resources is likely to increase and new approaches are needed to analyze future material and energy use of biomass globally and locally. Using Sweden as an example, we present an approach that combines global and national land-use and forest models to analyze impacts of climate change mitigation ambitions on forest management and harvesting in a specific country. National forest impact analyses in Sweden have traditionally focused on supply potential with little reference to international market developments. In this study, we use the global greenhouse gas concentration scenarios from the Intergovernmental Panel for Climate Change to estimate global biomass demand and assess potential implications on harvesting and biodiversity in Sweden. The results show that the short-term demand for wood is close to the full harvesting potential in Sweden in all scenarios. Under high bioenergy demand, harvest levels are projected to stay high over a longer time and particularly impact the harvest levels of pulpwood. The area of old forest in the managed landscape may decrease. This study highlights the importance of global scenarios when discussing national-level analysis and pinpoints trade-offs that policy making in Sweden may need to tackle in the near future.},
	language = {en},
	number = {12},
	urldate = {2021-06-07},
	journal = {Canadian Journal of Forest Research},
	author = {Nordström, Eva-Maria and Forsell, Nicklas and Lundström, Anders and Korosuo, Anu and Bergh, Johan and Havlík, Petr and Kraxner, Florian and Frank, Stefan and Fricko, Oliver and Lundmark, Tomas and Nordin, Annika},
	month = dec,
	year = {2016},
	pages = {1427--1438},
}

Under climate change, the importance of biomass resources is likely to increase and new approaches are needed to analyze future material and energy use of biomass globally and locally. Using Sweden as an example, we present an approach that combines global and national land-use and forest models to analyze impacts of climate change mitigation ambitions on forest management and harvesting in a specific country. National forest impact analyses in Sweden have traditionally focused on supply potential with little reference to international market developments. In this study, we use the global greenhouse gas concentration scenarios from the Intergovernmental Panel for Climate Change to estimate global biomass demand and assess potential implications on harvesting and biodiversity in Sweden. The results show that the short-term demand for wood is close to the full harvesting potential in Sweden in all scenarios. Under high bioenergy demand, harvest levels are projected to stay high over a longer time and particularly impact the harvest levels of pulpwood. The area of old forest in the managed landscape may decrease. This study highlights the importance of global scenarios when discussing national-level analysis and pinpoints trade-offs that policy making in Sweden may need to tackle in the near future.

@article{sponseller_nitrogen_2016,
	title = {Nitrogen dynamics in managed boreal forests: {Recent} advances and future research directions},
	volume = {45},
	issn = {0044-7447, 1654-7209},
	shorttitle = {Nitrogen dynamics in managed boreal forests},
	url = {http://link.springer.com/10.1007/s13280-015-0755-4},
	doi = {10.1007/s13280-015-0755-4},
	language = {en},
	number = {S2},
	urldate = {2021-06-07},
	journal = {Ambio},
	author = {Sponseller, Ryan A. and Gundale, Michael J. and Futter, Martyn and Ring, Eva and Nordin, Annika and Näsholm, Torgny and Laudon, Hjalmar},
	month = feb,
	year = {2016},
	pages = {175--187},
}

@article{roberge_socio-ecological_2016,
	title = {Socio-ecological implications of modifying rotation lengths in forestry},
	volume = {45},
	issn = {0044-7447, 1654-7209},
	url = {http://link.springer.com/10.1007/s13280-015-0747-4},
	doi = {10.1007/s13280-015-0747-4},
	language = {en},
	number = {S2},
	urldate = {2021-06-07},
	journal = {Ambio},
	author = {Roberge, Jean-Michel and Laudon, Hjalmar and Björkman, Christer and Ranius, Thomas and Sandström, Camilla and Felton, Adam and Sténs, Anna and Nordin, Annika and Granström, Anders and Widemo, Fredrik and Bergh, Johan and Sonesson, Johan and Stenlid, Jan and Lundmark, Tomas},
	month = feb,
	year = {2016},
	pages = {109--123},
}

@article{laudon_role_2016,
	title = {The role of biogeochemical hotspots, landscape heterogeneity, and hydrological connectivity for minimizing forestry effects on water quality},
	volume = {45},
	issn = {0044-7447, 1654-7209},
	url = {http://link.springer.com/10.1007/s13280-015-0751-8},
	doi = {10.1007/s13280-015-0751-8},
	language = {en},
	number = {S2},
	urldate = {2021-06-07},
	journal = {Ambio},
	author = {Laudon, Hjalmar and Kuglerová, Lenka and Sponseller, Ryan A. and Futter, Martyn and Nordin, Annika and Bishop, Kevin and Lundmark, Tomas and Egnell, Gustaf and Ågren, Anneli M.},
	month = feb,
	year = {2016},
	pages = {152--162},
}

@article{maaroufi_anthropogenic_2015,
	title = {Anthropogenic nitrogen deposition enhances carbon sequestration in boreal soils},
	volume = {21},
	issn = {1365-2486 (Electronic) 1354-1013 (Linking)},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/25711504},
	doi = {10.1111/gcb.12904},
	abstract = {It is proposed that carbon (C) sequestration in response to reactive nitrogen (Nr ) deposition in boreal forests accounts for a large portion of the terrestrial sink for anthropogenic CO2 emissions. While studies have helped clarify the magnitude by which Nr deposition enhances C sequestration by forest vegetation, there remains a paucity of long-term experimental studies evaluating how soil C pools respond. We conducted a long-term experiment, maintained since 1996, consisting of three N addition levels (0, 12.5, and 50 kg N ha(-1) yr(-1) ) in the boreal zone of northern Sweden to understand how atmospheric Nr deposition affects soil C accumulation, soil microbial communities, and soil respiration. We hypothesized that soil C sequestration will increase, and soil microbial biomass and soil respiration will decrease, with disproportionately large changes expected compared to low levels of N addition. Our data showed that the low N addition treatment caused a non-significant increase in the organic horizon C pool of {\textasciitilde}15\% and a significant increase of {\textasciitilde}30\% in response to the high N treatment relative to the control. The relationship between C sequestration and N addition in the organic horizon was linear, with a slope of 10 kg C kg(-1) N. We also found a concomitant decrease in total microbial and fungal biomasses and a {\textasciitilde}11\% reduction in soil respiration in response to the high N treatment. Our data complement previous data from the same study system describing aboveground C sequestration, indicating a total ecosystem sequestration rate of 26 kg C kg(-1) N. These estimates are far lower than suggested by some previous modeling studies, and thus will help improve and validate current modeling efforts aimed at separating the effect of multiple global change factors on the C balance of the boreal region.},
	language = {en},
	number = {8},
	urldate = {2021-06-07},
	journal = {Glob Chang Biol},
	author = {Maaroufi, N. I. and Nordin, A. and Hasselquist, N. J. and Bach, L. H. and Palmqvist, K. and Gundale, M. J.},
	month = aug,
	year = {2015},
	note = {Edition: 2015/02/26},
	keywords = {*Carbon Sequestration, *Taiga, Carbon/*analysis, Ecosystem, Nitrogen/*analysis, Soil Microbiology, Soil/chemistry, Sweden, boreal forest, boreal soil, carbon sequestration, carbon sink, nitrogen deposition, soil C pool, soil respiration},
	pages = {3169--80},
}

It is proposed that carbon (C) sequestration in response to reactive nitrogen (Nr ) deposition in boreal forests accounts for a large portion of the terrestrial sink for anthropogenic CO2 emissions. While studies have helped clarify the magnitude by which Nr deposition enhances C sequestration by forest vegetation, there remains a paucity of long-term experimental studies evaluating how soil C pools respond. We conducted a long-term experiment, maintained since 1996, consisting of three N addition levels (0, 12.5, and 50 kg N ha(-1) yr(-1) ) in the boreal zone of northern Sweden to understand how atmospheric Nr deposition affects soil C accumulation, soil microbial communities, and soil respiration. We hypothesized that soil C sequestration will increase, and soil microbial biomass and soil respiration will decrease, with disproportionately large changes expected compared to low levels of N addition. Our data showed that the low N addition treatment caused a non-significant increase in the organic horizon C pool of ~15% and a significant increase of ~30% in response to the high N treatment relative to the control. The relationship between C sequestration and N addition in the organic horizon was linear, with a slope of 10 kg C kg(-1) N. We also found a concomitant decrease in total microbial and fungal biomasses and a ~11% reduction in soil respiration in response to the high N treatment. Our data complement previous data from the same study system describing aboveground C sequestration, indicating a total ecosystem sequestration rate of 26 kg C kg(-1) N. These estimates are far lower than suggested by some previous modeling studies, and thus will help improve and validate current modeling efforts aimed at separating the effect of multiple global change factors on the C balance of the boreal region.

@article{hedwall_nitrogen-retention_2015,
	title = {Nitrogen-retention capacity in a fertilized forest after clear-cutting - the effect of forest-floor vegetation},
	volume = {45},
	issn = {0045-5067},
	url = {://WOS:000347297500015},
	doi = {10.1139/cjfr-2014-0281},
	abstract = {Forest fertilization with nitrogen (N) has several benefits to society such as increased wood production and carbon sequestration. There are, however, concerns about N leakage, particularly following clear-cutting. The forest-floor vegetation may increase the N retention of forest ecosystems; however, very few studies have quantified the amount of vegetation required. We studied the relationship between vegetation cover and risk of N leakage, estimated by the amounts of ammonium-N and nitrate-N retained on ion-exchange capsules in the soil, during 4 years following the clear-cutting and harvesting of logging residues in a previously fertilized forest in southern Sweden. Previous fertilization increased the amount of nitrate-N captured on the capsules, whereas the amount of ammonium-N decreased. The vascular vegetation cover increased from almost zero to approximately 25\% independent of fertilization. The amount of ammonium-N and nitrate-N retained on the capsules was already reduced by 50\%-75\% at 20\% vegetation cover, and by 30\%-40\% cover, it approached zero, independent of the number of years since clear-cutting. The vegetation may impede tree-seedling establishment, implying a trade-off between seedling growth and N-retention capacity. However, our results indicate that maximum N retention may be achieved at a relatively low vegetation cover, which could be accomplished with less intrusive scarification methods than currently used.},
	language = {English},
	number = {1},
	urldate = {2021-06-07},
	journal = {Canadian Journal of Forest Research},
	author = {Hedwall, P. O. and Bergh, J. and Nordin, A.},
	month = jan,
	year = {2015},
	keywords = {deposition, forest fertilization, ground vegetation, immobilization, intensities, management, nitrate, nitrogen, norway spruce, nutrient leakage, water},
	pages = {130--134},
}

Forest fertilization with nitrogen (N) has several benefits to society such as increased wood production and carbon sequestration. There are, however, concerns about N leakage, particularly following clear-cutting. The forest-floor vegetation may increase the N retention of forest ecosystems; however, very few studies have quantified the amount of vegetation required. We studied the relationship between vegetation cover and risk of N leakage, estimated by the amounts of ammonium-N and nitrate-N retained on ion-exchange capsules in the soil, during 4 years following the clear-cutting and harvesting of logging residues in a previously fertilized forest in southern Sweden. Previous fertilization increased the amount of nitrate-N captured on the capsules, whereas the amount of ammonium-N decreased. The vascular vegetation cover increased from almost zero to approximately 25% independent of fertilization. The amount of ammonium-N and nitrate-N retained on the capsules was already reduced by 50%-75% at 20% vegetation cover, and by 30%-40% cover, it approached zero, independent of the number of years since clear-cutting. The vegetation may impede tree-seedling establishment, implying a trade-off between seedling growth and N-retention capacity. However, our results indicate that maximum N retention may be achieved at a relatively low vegetation cover, which could be accomplished with less intrusive scarification methods than currently used.

@article{roberge_relative_2015,
	title = {Relative contributions of set-asides and tree retention to the long-term availability of key forest biodiversity structures at the landscape scale},
	volume = {154},
	issn = {1095-8630 (Electronic) 0301-4797 (Linking)},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/25745845},
	doi = {10/f3p26n},
	abstract = {Over previous decades new environmental measures have been implemented in forestry. In Fennoscandia, forest management practices were modified to set aside conservation areas and to retain trees at final felling. In this study we simulated the long-term effects of set-aside establishment and tree retention practices on the future availability of large trees and dead wood, two forest structures of documented importance to biodiversity conservation. Using a forest decision support system (Heureka), we projected the amounts of these structures over 200 years in two managed north Swedish landscapes, under management scenarios with and without set-asides and tree retention. In line with common best practice, we simulated set-asides covering 5\% of the productive area with priority to older stands, as well as approximately 5\% green-tree retention (solitary trees and forest patches) including high-stump creation at final felling. We found that only tree retention contributed to substantial increases in the future density of large (DBH {\textgreater}/=35 cm) deciduous trees, while both measures made significant contributions to the availability of large conifers. It took more than half a century to observe stronger increases in the densities of large deciduous trees as an effect of tree retention. The mean landscape-scale volumes of hard dead wood fluctuated widely, but the conservation measures yielded values which were, on average over the entire simulation period, about 2.5 times as high as for scenarios without these measures. While the density of large conifers increased with time in the landscape initially dominated by younger forest, best practice conservation measures did not avert a long-term decrease in large conifer density in the landscape initially comprised of more old forest. Our results highlight the needs to adopt a long temporal perspective and to consider initial landscape conditions when evaluating the large-scale effects of conservation measures on forest biodiversity.},
	language = {en},
	urldate = {2021-06-07},
	journal = {J Environ Manage},
	author = {Roberge, J. M. and Lamas, T. and Lundmark, T. and Ranius, T. and Felton, A. and Nordin, A.},
	month = may,
	year = {2015},
	note = {Edition: 2015/03/10},
	keywords = {*Biodiversity, *Trees, Biodiversity conservation, Conservation of Natural Resources, Dead wood, Ecosystem, Forest management, Forestry/*methods, Humans, Landscape simulations, Large trees, Sweden, Tree retention, Wood},
	pages = {284--92},
}

Over previous decades new environmental measures have been implemented in forestry. In Fennoscandia, forest management practices were modified to set aside conservation areas and to retain trees at final felling. In this study we simulated the long-term effects of set-aside establishment and tree retention practices on the future availability of large trees and dead wood, two forest structures of documented importance to biodiversity conservation. Using a forest decision support system (Heureka), we projected the amounts of these structures over 200 years in two managed north Swedish landscapes, under management scenarios with and without set-asides and tree retention. In line with common best practice, we simulated set-asides covering 5% of the productive area with priority to older stands, as well as approximately 5% green-tree retention (solitary trees and forest patches) including high-stump creation at final felling. We found that only tree retention contributed to substantial increases in the future density of large (DBH \textgreater/=35 cm) deciduous trees, while both measures made significant contributions to the availability of large conifers. It took more than half a century to observe stronger increases in the densities of large deciduous trees as an effect of tree retention. The mean landscape-scale volumes of hard dead wood fluctuated widely, but the conservation measures yielded values which were, on average over the entire simulation period, about 2.5 times as high as for scenarios without these measures. While the density of large conifers increased with time in the landscape initially dominated by younger forest, best practice conservation measures did not avert a long-term decrease in large conifer density in the landscape initially comprised of more old forest. Our results highlight the needs to adopt a long temporal perspective and to consider initial landscape conditions when evaluating the large-scale effects of conservation measures on forest biodiversity.

@article{from_residual_2015,
	title = {Residual {Long}-{Term} {Effects} of {Forest} {Fertilization} on {Tree} {Growth} and {Nitrogen} {Turnover} in {Boreal} {Forest}},
	volume = {6},
	issn = {1999-4907},
	url = {://WOS:000353775500015},
	doi = {10/f3p5c9},
	abstract = {The growth enhancing effects of forest fertilizer is considered to level off within 10 years of the application, and be restricted to one forest stand rotation. However, fertilizer induced changes in plant community composition has been shown to occur in the following stand rotation. To clarify whether effects of forest fertilization have residual long-term effects, extending into the next rotation, we compared tree growth, needle N concentrations and the availability of mobile soil N in young (10 years) Pinus sylvestris L. and Picea abies (L.) H. Karst. stands. The sites were fertilized with 150 kg center dot N center dot ha(-1) once or twice during the previous stand rotation, or unfertilized. Two fertilization events increased tree height by 24\% compared to the controls. Needle N concentrations of the trees on previously fertilized sites were 15\% higher than those of the controls. Soil N mineralization rates and the amounts of mobile soil NH4-N and NO3-N were higher on sites that were fertilized twice than on control sites. Our study demonstrates that operational forest fertilization can cause residual long-term effects on stand N dynamics, with subsequent effects on tree growth that may be more long-lasting than previously believed, i.e., extending beyond one stand rotation.},
	language = {English},
	number = {4},
	urldate = {2021-06-07},
	journal = {Forests},
	author = {From, F. and Strengbom, J. and Nordin, A.},
	month = apr,
	year = {2015},
	keywords = {availability, biomass, carbon, ground vegetation, picea-abies, pinus-sylvestris, soil},
	pages = {1145--1156},
}

The growth enhancing effects of forest fertilizer is considered to level off within 10 years of the application, and be restricted to one forest stand rotation. However, fertilizer induced changes in plant community composition has been shown to occur in the following stand rotation. To clarify whether effects of forest fertilization have residual long-term effects, extending into the next rotation, we compared tree growth, needle N concentrations and the availability of mobile soil N in young (10 years) Pinus sylvestris L. and Picea abies (L.) H. Karst. stands. The sites were fertilized with 150 kg center dot N center dot ha(-1) once or twice during the previous stand rotation, or unfertilized. Two fertilization events increased tree height by 24% compared to the controls. Needle N concentrations of the trees on previously fertilized sites were 15% higher than those of the controls. Soil N mineralization rates and the amounts of mobile soil NH4-N and NO3-N were higher on sites that were fertilized twice than on control sites. Our study demonstrates that operational forest fertilization can cause residual long-term effects on stand N dynamics, with subsequent effects on tree growth that may be more long-lasting than previously believed, i.e., extending beyond one stand rotation.

@article{gundale_anthropogenic_2014,
	title = {Anthropogenic nitrogen deposition in boreal forests has a minor impact on the global carbon cycle},
	volume = {20},
	issn = {13541013},
	url = {http://doi.wiley.com/10.1111/gcb.12422},
	doi = {10/f2zqdf},
	language = {en},
	number = {1},
	urldate = {2021-06-08},
	journal = {Global Change Biology},
	author = {Gundale, Michael J. and From, Fredrik and Bach, Lisbet H. and Nordin, Annika},
	month = jan,
	year = {2014},
	pages = {276--286},
}

@article{axelsson_belowground_2014,
	title = {Belowground {Competition} {Directs} {Spatial} {Patterns} of {Seedling} {Growth} in {Boreal} {Pine} {Forests} in {Fennoscandia}},
	volume = {5},
	issn = {1999-4907},
	url = {http://www.mdpi.com/1999-4907/5/9/2106},
	doi = {10/f25mnq},
	language = {en},
	number = {9},
	urldate = {2021-06-08},
	journal = {Forests},
	author = {Axelsson, E. and Lundmark, Tomas and Högberg, Peter and Nordin, Annika},
	month = sep,
	year = {2014},
	pages = {2106--2121},
}

@article{lundmark_potential_2014,
	title = {Potential {Roles} of {Swedish} {Forestry} in the {Context} of {Climate} {Change} {Mitigation}},
	volume = {5},
	issn = {1999-4907},
	url = {http://www.mdpi.com/1999-4907/5/4/557},
	doi = {10/f23f7n},
	language = {en},
	number = {4},
	urldate = {2021-06-08},
	journal = {Forests},
	author = {Lundmark, Tomas and Bergh, Johan and Hofer, Peter and Lundström, Anders and Nordin, Annika and Poudel, Bishnu and Sathre, Roger and Taverna, Ruedi and Werner, Frank},
	month = mar,
	year = {2014},
	pages = {557--578},
}

@article{mousavi_serum_2014,
	title = {Serum {Metabolomic} {Biomarkers} of {Dementia}},
	volume = {4},
	issn = {1664-5464},
	url = {https://www.karger.com/Article/FullText/364816},
	doi = {10/f242b6},
	language = {en},
	number = {2},
	urldate = {2021-06-08},
	journal = {Dementia and Geriatric Cognitive Disorders Extra},
	author = {Mousavi, Malahat and Jonsson, P�r and Antti, Henrik and Adolfsson, Rolf and Nordin, Annelie and Bergdahl, Jan and Eriksson, K�re and Moritz, Thomas and Nilsson, Lars-G�ran and Nyberg, Lars},
	month = jul,
	year = {2014},
	pages = {252--262},
}

@article{hedwall_can_2013,
	title = {Can thinning alleviate negative effects of fertilization on boreal forest floor vegetation?},
	volume = {310},
	issn = {03781127},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0378112713005677},
	doi = {10/f236wd},
	language = {en},
	urldate = {2021-06-08},
	journal = {Forest Ecology and Management},
	author = {Hedwall, P.-O. and Strengbom, J. and Nordin, A.},
	month = dec,
	year = {2013},
	pages = {382--392},
}

@article{hedwall_does_2013,
	title = {Does background nitrogen deposition affect the response of boreal vegetation to fertilization?},
	volume = {173},
	issn = {0029-8549, 1432-1939},
	url = {http://link.springer.com/10.1007/s00442-013-2638-3},
	doi = {10/f23wzh},
	language = {en},
	number = {2},
	urldate = {2021-06-08},
	journal = {Oecologia},
	author = {Hedwall, P. O. and Nordin, A. and Strengbom, J. and Brunet, J. and Olsson, B.},
	month = oct,
	year = {2013},
	pages = {615--624},
}

@article{gundale_impact_2013,
	title = {The impact of simulated chronic nitrogen deposition on the biomass and {N} $_{\textrm{2}}$ -fixation activity of two boreal feather moss–cyanobacteria associations},
	volume = {9},
	issn = {1744-9561, 1744-957X},
	url = {https://royalsocietypublishing.org/doi/10.1098/rsbl.2013.0797},
	doi = {10/f23kcz},
	abstract = {Bryophytes achieve substantial biomass and play several key functional roles in boreal forests that can influence how carbon (C) and nitrogen (N) cycling respond to atmospheric deposition of reactive nitrogen (N
              r
              ). They associate with cyanobacteria that fix atmospheric N
              2
              , and downregulation of this process may offset anthropogenic N
              r
              inputs to boreal systems. Bryophytes also promote soil C accumulation by thermally insulating soils, and changes in their biomass influence soil C dynamics. Using a unique large-scale (0.1 ha forested plots), long-term experiment (16 years) in northern Sweden where we simulated anthropogenic N
              r
              deposition, we measured the biomass and N
              2
              -fixation response of two bryophyte species, the feather mosses
              Hylocomium splendens
              and
              Pleurozium schreberi
              . Our data show that the biomass declined for both species; however, N
              2
              -fixation rates per unit mass and per unit area declined only for
              H. splendens
              . The low and high treatments resulted in a 29\% and 54\% reduction in total feather moss biomass, and a 58\% and 97\% reduction in total N
              2
              -fixation rate per unit area, respectively. These results help to quantify the sensitivity of feather moss biomass and N
              2
              fixation to chronic N
              r
              deposition, which is relevant for modelling ecosystem C and N balances in boreal ecosystems.},
	language = {en},
	number = {6},
	urldate = {2021-06-08},
	journal = {Biology Letters},
	author = {Gundale, Michael J. and Bach, Lisbet H. and Nordin, Annika},
	month = dec,
	year = {2013},
	pages = {20130797},
}

Bryophytes achieve substantial biomass and play several key functional roles in boreal forests that can influence how carbon (C) and nitrogen (N) cycling respond to atmospheric deposition of reactive nitrogen (N r ). They associate with cyanobacteria that fix atmospheric N 2 , and downregulation of this process may offset anthropogenic N r inputs to boreal systems. Bryophytes also promote soil C accumulation by thermally insulating soils, and changes in their biomass influence soil C dynamics. Using a unique large-scale (0.1 ha forested plots), long-term experiment (16 years) in northern Sweden where we simulated anthropogenic N r deposition, we measured the biomass and N 2 -fixation response of two bryophyte species, the feather mosses Hylocomium splendens and Pleurozium schreberi . Our data show that the biomass declined for both species; however, N 2 -fixation rates per unit mass and per unit area declined only for H. splendens . The low and high treatments resulted in a 29% and 54% reduction in total feather moss biomass, and a 58% and 97% reduction in total N 2 -fixation rate per unit area, respectively. These results help to quantify the sensitivity of feather moss biomass and N 2 fixation to chronic N r deposition, which is relevant for modelling ecosystem C and N balances in boreal ecosystems.

@article{strengbom_physical_2012,
	title = {Physical disturbance determines effects from nitrogen addition on ground vegetation in boreal coniferous forests},
	volume = {23},
	issn = {11009233},
	url = {http://doi.wiley.com/10.1111/j.1654-1103.2011.01359.x},
	doi = {10/b523g8},
	language = {en},
	number = {2},
	urldate = {2021-06-08},
	journal = {Journal of Vegetation Science},
	author = {Strengbom, Joachim and Nordin, Annika},
	editor = {Chiarucci, Alessandro},
	month = apr,
	year = {2012},
	pages = {361--371},
}

@article{gundale_bryophytes_2011,
	title = {Bryophytes attenuate anthropogenic nitrogen inputs in boreal forests: {BRYOPHYTES} {ATTENUATE} {NITROGEN} {DEPOSITION}},
	volume = {17},
	issn = {13541013},
	shorttitle = {Bryophytes attenuate anthropogenic nitrogen inputs in boreal forests},
	url = {http://doi.wiley.com/10.1111/j.1365-2486.2011.02407.x},
	doi = {10/b8mkq2},
	language = {en},
	number = {8},
	urldate = {2021-06-08},
	journal = {Global Change Biology},
	author = {Gundale, Michael J. and Deluca, Thomas H. and Nordin, Annika},
	month = aug,
	year = {2011},
	pages = {2743--2753},
}

@article{hedwall_decreased_2011,
	title = {Decreased variation of forest understory vegetation is an effect of fertilisation in young stands of {Picea} abies},
	volume = {26},
	issn = {0282-7581},
	url = {https://doi.org/10.1080/02827581.2011.564397},
	doi = {10.1080/02827581.2011.564397},
	abstract = {The substitution of fossil fuels with biofuels to mitigate climate change has caused increased interest in enhancing forest biomass production through fertilisation. We investigated the effects of different fertilisation frequencies on the diversity of understory vegetation in young stands of Picea abies on five sites distributed in regions in the middle and south of Sweden. The treatments included fertilisation conducted annually, every second year or every third year, as well as an unfertilised control. A lower number of vascular plant species was observed on fertilised plots than on control plots, whereas the number of bryophyte species remained unchanged. Fertilised plots also showed a lower variance in species composition and a lower Shannon's diversity index than unfertilised plots. Fertilised plots were more similar to each other than unfertilised plots were to each other over the geographical range. The two most intensive fertilisation treatments had similar effects on the vegetation, whereas the effects of fertilisation conducted every third year were not as substantial. However, the treatment in which fertilisation occurred every third year implies a lower stem-wood production, and there is little knowledge of the long-term differences between the treatments. We conclude that fertilisation of young stands will lead to long-term changes in understory vegetation at the stand scale, whereas the effects at the landscape level are still largely unknown.},
	number = {S11},
	urldate = {2021-06-08},
	journal = {Scandinavian Journal of Forest Research},
	author = {Hedwall, Per-Ola and Brunet, Jörg and Nordin, Annika and Bergh, Johan},
	month = jun,
	year = {2011},
	note = {Publisher: Taylor \& Francis
\_eprint: https://doi.org/10.1080/02827581.2011.564397},
	keywords = {Norway spruce, Plant diversity, bryophytes, lichens, nitrogen},
	pages = {46--55},
}

The substitution of fossil fuels with biofuels to mitigate climate change has caused increased interest in enhancing forest biomass production through fertilisation. We investigated the effects of different fertilisation frequencies on the diversity of understory vegetation in young stands of Picea abies on five sites distributed in regions in the middle and south of Sweden. The treatments included fertilisation conducted annually, every second year or every third year, as well as an unfertilised control. A lower number of vascular plant species was observed on fertilised plots than on control plots, whereas the number of bryophyte species remained unchanged. Fertilised plots also showed a lower variance in species composition and a lower Shannon's diversity index than unfertilised plots. Fertilised plots were more similar to each other than unfertilised plots were to each other over the geographical range. The two most intensive fertilisation treatments had similar effects on the vegetation, whereas the effects of fertilisation conducted every third year were not as substantial. However, the treatment in which fertilisation occurred every third year implies a lower stem-wood production, and there is little knowledge of the long-term differences between the treatments. We conclude that fertilisation of young stands will lead to long-term changes in understory vegetation at the stand scale, whereas the effects at the landscape level are still largely unknown.

@article{cambui_patterns_2011,
	title = {Patterns of {Plant} {Biomass} {Partitioning} {Depend} on {Nitrogen} {Source}},
	volume = {6},
	issn = {1932-6203},
	url = {https://dx.plos.org/10.1371/journal.pone.0019211},
	doi = {10/d3w26r},
	language = {en},
	number = {4},
	urldate = {2021-06-08},
	journal = {PLoS ONE},
	author = {Cambui, Camila Aguetoni and Svennerstam, Henrik and Gruffman, Linda and Nordin, Annika and Ganeteg, Ulrika and Näsholm, Torgny},
	editor = {Weigelt, Alexandra},
	month = apr,
	year = {2011},
	pages = {e19211},
}

@article{hedwall_compositional_2010,
	title = {Compositional changes of forest-floor vegetation in young stands of {Norway} spruce as an effect of repeated fertilisation},
	volume = {259},
	issn = {03781127},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0378112710001714},
	doi = {10/fv8s3x},
	language = {en},
	number = {12},
	urldate = {2021-06-08},
	journal = {Forest Ecology and Management},
	author = {Hedwall, Per-Ola and Nordin, Annika and Brunet, Jörg and Bergh, Johan},
	month = may,
	year = {2010},
	pages = {2418--2425},
}

@article{bobbink_global_2010,
	title = {Global assessment of nitrogen deposition effects on terrestrial plant diversity: a synthesis},
	volume = {20},
	issn = {1051-0761},
	shorttitle = {Global assessment of nitrogen deposition effects on terrestrial plant diversity},
	url = {http://doi.wiley.com/10.1890/08-1140.1},
	doi = {10/cmgxt6},
	language = {en},
	number = {1},
	urldate = {2021-06-08},
	journal = {Ecological Applications},
	author = {Bobbink, R. and Hicks, K. and Galloway, J. and Spranger, T. and Alkemade, R. and Ashmore, M. and Bustamante, M. and Cinderby, S. and Davidson, E. and Dentener, F. and Emmett, B. and Erisman, J-W. and Fenn, M. and Gilliam, F. and Nordin, A. and Pardo, L. and De Vries, W.},
	month = jan,
	year = {2010},
	pages = {30--59},
}

@article{ishida_no_2010,
	title = {No evidence that nitrogen enrichment affect fungal communities of {Vaccinium} roots in two contrasting boreal forest types},
	volume = {42},
	issn = {00380717},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0038071709003988},
	doi = {10/d26fvw},
	language = {en},
	number = {2},
	urldate = {2021-06-08},
	journal = {Soil Biology and Biochemistry},
	author = {Ishida, Takahide A. and Nordin, Annika},
	month = feb,
	year = {2010},
	pages = {234--243},
}

@article{johansson_responses_2010,
	title = {Responses of epiphytic lichens to an experimental whole‐tree nitrogen‐deposition gradient},
	volume = {188},
	issn = {0028-646X, 1469-8137},
	url = {https://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2010.03426.x},
	doi = {10/b58824},
	language = {en},
	number = {4},
	urldate = {2021-06-08},
	journal = {New Phytologist},
	author = {Johansson, Otilia and Nordin, Annika and Olofsson, Johan and Palmqvist, Kristin},
	month = dec,
	year = {2010},
	pages = {1075--1084},
}

@article{wiedermann_can_2009,
	title = {Can small-scale experiments predict ecosystem responses? {An} example from peatlands},
	volume = {118},
	issn = {00301299, 16000706},
	shorttitle = {Can small-scale experiments predict ecosystem responses?},
	url = {http://doi.wiley.com/10.1111/j.1600-0706.2008.17129.x},
	doi = {10/dxrvzs},
	language = {en},
	number = {3},
	urldate = {2021-06-10},
	journal = {Oikos},
	author = {Wiedermann, Magdalena M. and Gunnarsson, Urban and Nilsson, Mats B. and Nordin, Annika and Ericson, Lars},
	month = mar,
	year = {2009},
	pages = {449--456},
}

@article{nordin_complex_2009,
	title = {Complex {Biotic} {Interactions} {Drive} {Long}-{Term} {Vegetation} {Change} in a {Nitrogen} {Enriched} {Boreal} {Forest}},
	volume = {12},
	issn = {1432-9840, 1435-0629},
	url = {http://link.springer.com/10.1007/s10021-009-9287-8},
	doi = {10/dtjs7b},
	language = {en},
	number = {7},
	urldate = {2021-06-08},
	journal = {Ecosystems},
	author = {Nordin, Annika and Strengbom, Joachim and Forsum, Åsa and Ericson, Lars},
	month = nov,
	year = {2009},
	pages = {1204--1211},
}

@article{wiedermann_ecophysiological_2009,
	title = {Ecophysiological adjustment of two \textit{{Sphagnum}} species in response to anthropogenic nitrogen deposition},
	volume = {181},
	issn = {0028-646X, 1469-8137},
	url = {https://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2008.02628.x},
	doi = {10/fdmwzb},
	language = {en},
	number = {1},
	urldate = {2021-06-08},
	journal = {New Phytologist},
	author = {Wiedermann, Magdalena M. and Gunnarsson, Urban and Ericson, Lars and Nordin, Annika},
	month = jan,
	year = {2009},
	pages = {208--217},
}

@article{strengbom_commercial_2008,
	title = {Commercial forest fertilization causes long-term residual effects in ground vegetation of boreal forests},
	volume = {256},
	issn = {03781127},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0378112708006178},
	doi = {10/ch24fw},
	language = {en},
	number = {12},
	urldate = {2021-06-10},
	journal = {Forest Ecology and Management},
	author = {Strengbom, Joachim and Nordin, Annika},
	month = dec,
	year = {2008},
	pages = {2175--2181},
}

@article{forsum_nitrogen_2008,
	title = {Nitrogen uptake by \textit{{Hylocomium} splendens} during snowmelt in a boreal forest},
	volume = {15},
	issn = {1195-6860, 2376-7626},
	url = {https://www.tandfonline.com/doi/full/10.2980/15-3-3141},
	doi = {10/bp7d7w},
	language = {en},
	number = {3},
	urldate = {2021-06-10},
	journal = {Écoscience},
	author = {Forsum, Åsa and Laudon, Hjalmar and Nordin, Annika},
	month = sep,
	year = {2008},
	pages = {315--319},
}

@article{wiedermann_global_2007,
	title = {{GLOBAL} {CHANGE} {SHIFTS} {VEGETATION} {AND} {PLANT}–{PARASITE} {INTERACTIONS} {IN} {A} {BOREAL} {MIRE}},
	volume = {88},
	issn = {0012-9658},
	url = {http://doi.wiley.com/10.1890/05-1823},
	doi = {10/d9c3bc},
	language = {en},
	number = {2},
	urldate = {2021-06-10},
	journal = {Ecology},
	author = {Wiedermann, Magdalena M. and Nordin, Annika and Gunnarsson, Urban and Nilsson, Mats B. and Ericson, Lars},
	month = feb,
	year = {2007},
	pages = {454--464},
}

@article{forsum_nitrogen_2006,
	title = {Nitrogen utilization by {Hylocomium} splendens in a boreal forest fertilization experiment},
	volume = {20},
	issn = {0269-8463},
	doi = {10.1111/j.1365-2435.2006.01127.x},
	abstract = {1. Nitrogen uptake in the terricolous bryophyte Hylocomium splendens (Hedw.) B.S.G. was studied in a boreal forest long-term N-treatment experiment including control plots, N-addition plots (50 kg N ha(-1) year(-1) for 8 years) and recovery plots (50 kg N ha(-1) year(-1) for 5 years and thereafter no N addition for 3 years). 2.A main objective was to explore whether the N treatments changed bryophyte uptake of different inorganic and organic N forms. In addition, we estimated the contribution of N from throughfall precipitation to the bryophyte N supply. 3. The results demonstrated that bryophyte N uptake was similar in all the long-term N-treatment plots. Hylocomium splendens took up more N-15 labelled NH4+ than NO3- or glycine when these N forms were applied in situ by the spraying of solutions with N concentrations similar to those in precipitation. 4. Analysis of the precipitation collected beneath the closed tree canopy from late May to early October revealed that it contributed 2.0 kg N ha(-1) during the period studied, distributed between NH4+ (78\%), amino acid N (17\%) and NO3- (5\%). 5. The study highlights that, in addition to analyses of NH4+ and NO3- (normally included in standard environmental monitoring of precipitation), analysis of amino acid N must be performed to account fully for the precipitation N input to bryophytes in boreal forest ecosystems.},
	language = {English},
	number = {3},
	journal = {Functional Ecology},
	author = {Forsum, A. and Dahlman, L. and Nasholm, T. and Nordin, A.},
	month = jun,
	year = {2006},
	note = {Place: Hoboken
Publisher: Wiley
WOS:000238185400002},
	keywords = {amino acids, amino-acids, ammonium, arginine, atmospheric deposition, canopy interactions, growth, nitrate, organic nitrogen, pinus-sylvestris, responses, soluble carbohydrates, sphagnum, throughfall, vegetation},
	pages = {421--426},
}

1. Nitrogen uptake in the terricolous bryophyte Hylocomium splendens (Hedw.) B.S.G. was studied in a boreal forest long-term N-treatment experiment including control plots, N-addition plots (50 kg N ha(-1) year(-1) for 8 years) and recovery plots (50 kg N ha(-1) year(-1) for 5 years and thereafter no N addition for 3 years). 2.A main objective was to explore whether the N treatments changed bryophyte uptake of different inorganic and organic N forms. In addition, we estimated the contribution of N from throughfall precipitation to the bryophyte N supply. 3. The results demonstrated that bryophyte N uptake was similar in all the long-term N-treatment plots. Hylocomium splendens took up more N-15 labelled NH4+ than NO3- or glycine when these N forms were applied in situ by the spraying of solutions with N concentrations similar to those in precipitation. 4. Analysis of the precipitation collected beneath the closed tree canopy from late May to early October revealed that it contributed 2.0 kg N ha(-1) during the period studied, distributed between NH4+ (78%), amino acid N (17%) and NO3- (5%). 5. The study highlights that, in addition to analyses of NH4+ and NO3- (normally included in standard environmental monitoring of precipitation), analysis of amino acid N must be performed to account fully for the precipitation N input to bryophytes in boreal forest ecosystems.

@article{nordin_responses_2006,
	title = {Responses to ammonium and nitrate additions by boreal plants and their natural enemies},
	volume = {141},
	issn = {0269-7491},
	doi = {10.1016/j.envpol.2005.08.017},
	abstract = {Separate effects of ammonium (NH4+) and nitrate (NO3-) on boreal forest understorey vegetation were investigated in an experiment where 12.5 and 50.0 kg nitrogen (N) hat year' was added to 2 m(2) sized plots during 4 years. The dwarf-shrubs dominating the plant community, Vaccinium myrtillus and V. vitis-idaea, took up little of the added N independent of the chemical form. and their growth did not respond to the N treatments. The grass Deschampsia flexuosa increased from the N additions and most so in response to NO3-. Bryophytes took up predominately NH4+ and there was a negative correlation between moss N concentration and abundance. Plant pathogenic fungi increased from the N additions, but showed no differences in response to the two N forms. Because the relative contribution of NH4+ and NO3- to the total N deposition on a regional scale can vary substantially, the N load a habitat can sustain without substantial changes in the biota should be set considering specific vegetation responses to the predominant N form in deposition. (c) 2005 Elsevier Ltd. All rights reserved.},
	language = {English},
	number = {1},
	journal = {Environmental Pollution},
	author = {Nordin, A. and Strengbom, J. and Ericson, L.},
	month = may,
	year = {2006},
	note = {Place: Oxford
Publisher: Elsevier Sci Ltd
WOS:000236771400018},
	keywords = {N deposition, N form, N uptake, atmospheric nitrogen, bryophytes, community, density, deposition, growth, pathogen, pathogenic fungi, productivity, species-diversity, valdensinia-heterodoxa, vegetation change},
	pages = {167--174},
}

Separate effects of ammonium (NH4+) and nitrate (NO3-) on boreal forest understorey vegetation were investigated in an experiment where 12.5 and 50.0 kg nitrogen (N) hat year' was added to 2 m(2) sized plots during 4 years. The dwarf-shrubs dominating the plant community, Vaccinium myrtillus and V. vitis-idaea, took up little of the added N independent of the chemical form. and their growth did not respond to the N treatments. The grass Deschampsia flexuosa increased from the N additions and most so in response to NO3-. Bryophytes took up predominately NH4+ and there was a negative correlation between moss N concentration and abundance. Plant pathogenic fungi increased from the N additions, but showed no differences in response to the two N forms. Because the relative contribution of NH4+ and NO3- to the total N deposition on a regional scale can vary substantially, the N load a habitat can sustain without substantial changes in the biota should be set considering specific vegetation responses to the predominant N form in deposition. (c) 2005 Elsevier Ltd. All rights reserved.

@article{strengbom_multitrophic_2005,
	title = {Do multitrophic interactions override {N} fertilization effects on {Operophtera} larvae?},
	volume = {143},
	issn = {1432-1939},
	url = {https://doi.org/10.1007/s00442-004-1799-5},
	doi = {10/fqbq2g},
	abstract = {We examined how performance of Operophtera brumata (Lepidoptera) larvae was affected by nitrogen (N) fertilization of boreal forest understorey vegetation. We monitored larval densities on Vaccinium myrtillus plants for a period of 7 years in a field experiment. Preliminary results indicated that the N effect on larval densities was weak. To examine if this was due to indirect interactions with a plant pathogen, Valdensia heterodoxa, that share the same host plant, or due to top-down effects of predation, we performed both a laboratory feeding experiment (individual level) and a bird exclusion experiment (population level) in the field. At the individual level, altered food plant quality (changes in plant concentration of carbon, N, phenolics, or condensed tannins) due to repeated infection by the pathogen had no effect on larval performance, but both survival to the adult stage and adult weight were positively affected by N fertilization. Exclusion of insectivorous birds increased the frequency of larval damage on V. myrtillus shoots, indicating higher larval densities. This effect was stronger in fertilized than in unfertilized plots, indicating higher bird predation in fertilized plots. Predation may thus explain the lack of fertilization effect on larval densities in the field experiment. Our results suggest that top-down effects are more important for larval densities than bottom-up effects, and that bird predation may play an important role in population regulation of O. brumata in boreal forests.},
	language = {en},
	number = {2},
	urldate = {2021-06-11},
	journal = {Oecologia},
	author = {Strengbom, Joachim and Witzell, Johanna and Nordin, Annika and Ericson, Lars},
	month = mar,
	year = {2005},
	pages = {241--250},
}

We examined how performance of Operophtera brumata (Lepidoptera) larvae was affected by nitrogen (N) fertilization of boreal forest understorey vegetation. We monitored larval densities on Vaccinium myrtillus plants for a period of 7 years in a field experiment. Preliminary results indicated that the N effect on larval densities was weak. To examine if this was due to indirect interactions with a plant pathogen, Valdensia heterodoxa, that share the same host plant, or due to top-down effects of predation, we performed both a laboratory feeding experiment (individual level) and a bird exclusion experiment (population level) in the field. At the individual level, altered food plant quality (changes in plant concentration of carbon, N, phenolics, or condensed tannins) due to repeated infection by the pathogen had no effect on larval performance, but both survival to the adult stage and adult weight were positively affected by N fertilization. Exclusion of insectivorous birds increased the frequency of larval damage on V. myrtillus shoots, indicating higher larval densities. This effect was stronger in fertilized than in unfertilized plots, indicating higher bird predation in fertilized plots. Predation may thus explain the lack of fertilization effect on larval densities in the field experiment. Our results suggest that top-down effects are more important for larval densities than bottom-up effects, and that bird predation may play an important role in population regulation of O. brumata in boreal forests.

@article{nordin_nitrogen_2005,
	title = {Nitrogen deposition and the biodiversity of boreal forests: {Implications} for the nitrogen critical load},
	volume = {34},
	issn = {0044-7447},
	shorttitle = {Nitrogen deposition and the biodiversity of boreal forests},
	doi = {10.1639/0044-7447(2005)034[0020:NDATBO]2.0.CO;2},
	abstract = {The critical load concept is used to establish the deposition levels which ecosystems can tolerate without significant harmful effects. Here we summarize work within the Swedish research program Abatement Strategies for Transboundary Air Pollution (ASTA) assessing the critical load of N for boreal forests. Results from both field experiments in an area with low background N deposition in northern Sweden, and from a large-scale monitoring study, show that important vegetational changes start to take place when adding low N doses and that recovery of the vegetation after ceasing N input is a very slow process. The data presented indicate that changes in key ecosystem components occur even at a lower rate of N input than the present recommended empirical critical load for boreal forest understorey vegetation of 10-15 kg N ha(-1) yr(-1). Based on the data presented, we suggest that the critical load should be lowered to 6 kg N ha(-1) yr(-1).},
	language = {English},
	number = {1},
	journal = {Ambio},
	author = {Nordin, A. and Strengbom, J. and Witzell, J. and Nasholm, T. and Ericson, L.},
	month = feb,
	year = {2005},
	note = {Place: Dordrecht
Publisher: Springer
WOS:000226782600003},
	keywords = {accumulation, acidification, bryophytes, diversity, ecosystem, fertilization, growth, plants, sphagnum, vegetation},
	pages = {20--24},
}

The critical load concept is used to establish the deposition levels which ecosystems can tolerate without significant harmful effects. Here we summarize work within the Swedish research program Abatement Strategies for Transboundary Air Pollution (ASTA) assessing the critical load of N for boreal forests. Results from both field experiments in an area with low background N deposition in northern Sweden, and from a large-scale monitoring study, show that important vegetational changes start to take place when adding low N doses and that recovery of the vegetation after ceasing N input is a very slow process. The data presented indicate that changes in key ecosystem components occur even at a lower rate of N input than the present recommended empirical critical load for boreal forest understorey vegetation of 10-15 kg N ha(-1) yr(-1). Based on the data presented, we suggest that the critical load should be lowered to 6 kg N ha(-1) yr(-1).

@article{nordin_nitrogen_2004,
	title = {Nitrogen uptake by arctic soil microbes and plants in relation to soil nitrogen supply},
	volume = {85},
	issn = {0012-9658},
	doi = {10.1890/03-0084},
	abstract = {In Alaska, evergreen and deciduous shrubs dominate the vegetation of moist acidic arctic tundra (soil pH {\textless} 5.5) while graminoids and forbs are important at the more species-rich moist nonacidic arctic tundra (soil pH {\textgreater} 5.5). In this study we compare soil concentrations and microbial and plant uptake of amino acids, ammonium (NH4+), and nitrate (NO3-) in acidic and nonacidic tundra. The objective was to determine any differences between the tundra sites that may relate to the differences in vegetation. We sampled the water-extractable soil N pool over one growing season and found that it at all times was higher at the nonacidic than at the acidic site, while at both sites it was dominated by NH4+ followed in order by amino acid N and NO3-. In addition, we designed an experiment in which a mixture of aspartic acid, glycine, NH4+, and NO3- were injected into the soil in the middle of the growth period. In the mixture, one N form at a time was labeled with N-15 and in the case of amino acids also with C-13. Soil and plant samples were collected 4 h following the injection of labeled N. A large portion of the experimental N was recovered in the soil microbial biomass (on average 49\% at the acidic site and 40\% at the nonacidic site), while less than 1\% was recovered in plants. Soil microbes and plants at both acidic and nonacidic tundra were able to take up all isotopically labeled N forms in the presence of added unlabeled N, demonstrating adequate potential to use any N form available. In addition, gas chromatography-mass spectrometry (GC-MS) analysis of plant roots revealed plant uptake of intact glycine, while isotopically labeled aspartic acid was not recovered inside plants.},
	language = {English},
	number = {4},
	journal = {Ecology},
	author = {Nordin, A. and Schmidt, I. K. and Shaver, G. R.},
	month = apr,
	year = {2004},
	note = {Place: Washington
Publisher: Ecological Soc Amer
WOS:000220766600007},
	keywords = {(nh4+)-n-15, (no3-)-n-15, C-13-N-15-amino acids, amino-acid, arctic vegetation, biomass, biosynthesis, boreal forest, calibration, fumigation-extraction method, growth, inorganic nitrogen, metabolism, nitrogen uptake, organic-nitrogen, soil PH, tundra},
	pages = {955--962},
}

In Alaska, evergreen and deciduous shrubs dominate the vegetation of moist acidic arctic tundra (soil pH \textless 5.5) while graminoids and forbs are important at the more species-rich moist nonacidic arctic tundra (soil pH \textgreater 5.5). In this study we compare soil concentrations and microbial and plant uptake of amino acids, ammonium (NH4+), and nitrate (NO3-) in acidic and nonacidic tundra. The objective was to determine any differences between the tundra sites that may relate to the differences in vegetation. We sampled the water-extractable soil N pool over one growing season and found that it at all times was higher at the nonacidic than at the acidic site, while at both sites it was dominated by NH4+ followed in order by amino acid N and NO3-. In addition, we designed an experiment in which a mixture of aspartic acid, glycine, NH4+, and NO3- were injected into the soil in the middle of the growth period. In the mixture, one N form at a time was labeled with N-15 and in the case of amino acids also with C-13. Soil and plant samples were collected 4 h following the injection of labeled N. A large portion of the experimental N was recovered in the soil microbial biomass (on average 49% at the acidic site and 40% at the nonacidic site), while less than 1% was recovered in plants. Soil microbes and plants at both acidic and nonacidic tundra were able to take up all isotopically labeled N forms in the presence of added unlabeled N, demonstrating adequate potential to use any N form available. In addition, gas chromatography-mass spectrometry (GC-MS) analysis of plant roots revealed plant uptake of intact glycine, while isotopically labeled aspartic acid was not recovered inside plants.

@article{schmidt_mineralization_2002,
	title = {Mineralization and distribution of nutrients in plants and microbes in four arctic ecosystems: responses to warming},
	volume = {242},
	issn = {1573-5036},
	shorttitle = {Mineralization and distribution of nutrients in plants and microbes in four arctic ecosystems},
	url = {https://doi.org/10.1023/A:1019642007929},
	doi = {10/bh8mzs},
	abstract = {Mineralization and nutrient distribution in plants and microbes were studied in four arctic ecosystems at Abisko, Northern Sweden and Toolik Lake, Alaska, which have been subjected to long-term warming with plastic greenhouses. Net mineralization and microbial immobilization were studied by the buried bag method and ecosystem pool sizes of C, N and P were determined by harvest methods. The highest amounts of organic N and P were bound in the soil organic matter. Microbial N and P constituted the largest labile pools often equal to (N) or exceeding (P) the amounts stored in the vegetation. Despite large pools of N and P in the soil, net mineralization of N and P was generally low during the growing season, except in the wet sedge tundra, and in most cases lower than the plant uptake requirement. In contrast, the microorganisms immobilized high amounts of nutrients in the buried bags during incubation. The same high immobilization was not observed in the surrounding soil, where the microbial nutrient content in most cases remained constant or decreased over the growing season. This suggests that the low mineralization measured in many arctic ecosystems over the growing season is due to increased immobilization by soil microbes when competition from plant roots is prevented. Furthermore, it suggests that plants compete well with microbes for nutrients in these four ecosystems. Warming increased net mineralization in several cases, which led to increased assimilation of nutrients by plants but not by the microbes.},
	language = {en},
	number = {1},
	urldate = {2021-10-19},
	journal = {Plant and Soil},
	author = {Schmidt, I.K. and Jonasson, S. and Shaver, G. R. and Michelsen, A. and Nordin, A.},
	month = may,
	year = {2002},
	pages = {93--106},
}

Mineralization and nutrient distribution in plants and microbes were studied in four arctic ecosystems at Abisko, Northern Sweden and Toolik Lake, Alaska, which have been subjected to long-term warming with plastic greenhouses. Net mineralization and microbial immobilization were studied by the buried bag method and ecosystem pool sizes of C, N and P were determined by harvest methods. The highest amounts of organic N and P were bound in the soil organic matter. Microbial N and P constituted the largest labile pools often equal to (N) or exceeding (P) the amounts stored in the vegetation. Despite large pools of N and P in the soil, net mineralization of N and P was generally low during the growing season, except in the wet sedge tundra, and in most cases lower than the plant uptake requirement. In contrast, the microorganisms immobilized high amounts of nutrients in the buried bags during incubation. The same high immobilization was not observed in the surrounding soil, where the microbial nutrient content in most cases remained constant or decreased over the growing season. This suggests that the low mineralization measured in many arctic ecosystems over the growing season is due to increased immobilization by soil microbes when competition from plant roots is prevented. Furthermore, it suggests that plants compete well with microbes for nutrients in these four ecosystems. Warming increased net mineralization in several cases, which led to increased assimilation of nutrients by plants but not by the microbes.

@article{strengbom_parasitic_2002,
	title = {Parasitic fungus mediates change in nitrogen-exposed boreal forest vegetation},
	volume = {90},
	issn = {1365-2745},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1046/j.0022-0477.2001.00629.x},
	doi = {10/bgscwh},
	abstract = {1 Experimental additions of N to an old-growth boreal forest resulted in elevated levels of free amino acids in leaves of the dominant dwarf-shrub Vaccinium myrtillus and increased attack from a parasitic fungus, Valdensia heterodoxa. 2 Glutamine additions to the leaf surface of V. myrtillus increased disease incidence by an average of almost three times compared to controls and suggested a causal connection between amino acid availability and fungal infection. 3 Increased abundance of the grass Deschampsia flexuosa followed N addition but infection by the parasitic fungus, which causes premature leaf loss of its primary host V. myrtillus, explained four times as much of the variation in grass abundance as N did. 4 Nitrogen deposition can have marked effects on vegetation by affecting the interaction between dominant hosts and their natural enemies. A shift in abundance of dominating species occurred within 3 years of treatment, with nitrogen loads similar to those deposited over large areas in Europe and North America, suggesting that such effects may by important for the vegetation of large areas subjected to low levels of nitrogen input.},
	language = {en},
	number = {1},
	urldate = {2021-10-19},
	journal = {Journal of Ecology},
	author = {Strengbom, Joachim and Nordin, Annika and Näsholm, Torgny and Ericson, Lars},
	year = {2002},
	note = {\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.0022-0477.2001.00629.x},
	keywords = {Deschampsia flexuosa, Vaccinium myrtillus, Valdensia heterodoxa, free amino acids, natural enemies, nitrogen deposition},
	pages = {61--67},
}

1 Experimental additions of N to an old-growth boreal forest resulted in elevated levels of free amino acids in leaves of the dominant dwarf-shrub Vaccinium myrtillus and increased attack from a parasitic fungus, Valdensia heterodoxa. 2 Glutamine additions to the leaf surface of V. myrtillus increased disease incidence by an average of almost three times compared to controls and suggested a causal connection between amino acid availability and fungal infection. 3 Increased abundance of the grass Deschampsia flexuosa followed N addition but infection by the parasitic fungus, which causes premature leaf loss of its primary host V. myrtillus, explained four times as much of the variation in grass abundance as N did. 4 Nitrogen deposition can have marked effects on vegetation by affecting the interaction between dominant hosts and their natural enemies. A shift in abundance of dominating species occurred within 3 years of treatment, with nitrogen loads similar to those deposited over large areas in Europe and North America, suggesting that such effects may by important for the vegetation of large areas subjected to low levels of nitrogen input.

@article{nordin_nitrogen_2001,
	title = {Nitrogen forms in bark, wood and foliage of nitrogen-fertilized {Pinus} sylvestris},
	volume = {21},
	issn = {0829-318X},
	url = {https://doi.org/10.1093/treephys/21.1.59},
	doi = {10/fz2v7x},
	abstract = {Cycling of soluble non-protein N compounds is thought to be indicative of the N-nutritional status of trees. We determined the major N forms in bark, wood and foliage and estimated the dependence of prevalent N forms on N availability in Pinus sylvestris L. trees from northern Sweden. Trees subjected to severe N limitation and trees that had been fertilized with an average 64 kg N ha−1 year−1 for 25 years were analyzed. Bark and wood samples were collected by tangentially cryo-sectioning the trunk into 30-μm thick sections, from the bark to the functional xylem. Soluble amino compounds were extracted from the sections for analysis. Sap samples from twigs were obtained by centrifugation, and bark samples from twigs were obtained by tissue extraction.In both needles and bark, arginine dominated the amino-N pool. Because arginine concentrations in needles increased with N fertilization, arginine dominance of the amino-N pool in needles was higher in N-fertilized trees than in control trees. In bark, N fertilization resulted in a large increase in glutamine concentration, so that glutamine accounted for a larger proportion of the amino-N pool in bark in N-fertilized trees than in control trees. Glutamine dominated the amino-N pool in wood of control trees. Nitrogen fertilization resulted in an increased proportion of arginine in the wood amino-N pool. We conclude that the composition of the amino-N pools in bark, wood and foliage is highly sensitive to N supply. The composition of the amino-N pools can contribute to the regulation of tree N-nutritional status, which is mediated by shoot to root signalling by long-distance transport of amino compounds.},
	number = {1},
	urldate = {2021-11-02},
	journal = {Tree Physiology},
	author = {Nordin, Annika and Uggla, Claes and Näsholm, Torgny},
	month = jan,
	year = {2001},
	pages = {59--64},
}

Cycling of soluble non-protein N compounds is thought to be indicative of the N-nutritional status of trees. We determined the major N forms in bark, wood and foliage and estimated the dependence of prevalent N forms on N availability in Pinus sylvestris L. trees from northern Sweden. Trees subjected to severe N limitation and trees that had been fertilized with an average 64 kg N ha−1 year−1 for 25 years were analyzed. Bark and wood samples were collected by tangentially cryo-sectioning the trunk into 30-μm thick sections, from the bark to the functional xylem. Soluble amino compounds were extracted from the sections for analysis. Sap samples from twigs were obtained by centrifugation, and bark samples from twigs were obtained by tissue extraction.In both needles and bark, arginine dominated the amino-N pool. Because arginine concentrations in needles increased with N fertilization, arginine dominance of the amino-N pool in needles was higher in N-fertilized trees than in control trees. In bark, N fertilization resulted in a large increase in glutamine concentration, so that glutamine accounted for a larger proportion of the amino-N pool in bark in N-fertilized trees than in control trees. Glutamine dominated the amino-N pool in wood of control trees. Nitrogen fertilization resulted in an increased proportion of arginine in the wood amino-N pool. We conclude that the composition of the amino-N pools in bark, wood and foliage is highly sensitive to N supply. The composition of the amino-N pools can contribute to the regulation of tree N-nutritional status, which is mediated by shoot to root signalling by long-distance transport of amino compounds.

@article{strengbom_slow_2001,
	title = {Slow recovery of boreal forest ecosystem following decreased nitrogen input},
	volume = {15},
	issn = {1365-2435},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1046/j.0269-8463.2001.00538.x},
	doi = {10/dnx7bp},
	abstract = {1 Ecosystem recovery after decreased input of nitrogen was examined in two different fertilization experiments where the fertilization had been terminated for 9 and 47 years, respectively. 2 The species composition of the understorey vegetation showed no signs of recovery 9 years after the fertilization was terminated. Increased sporocarp production of mycorrhizal fungi was seen on formerly fertilized plots compared with plots still receiving N, but the species composition showed large differences compared to control plots. 3 In the second experiment, examined 47 years after termination of fertilization, N favoured bryophytes such as Brachythecium reflexum (Starke) Schimp., Plagiothecium denticulatum (Hedw.) Schimp. and the leaf-parasitic fungus Valdensia heterodoxa Peyronel (attacking Vaccinium myrtillus L.) was more abundant in the formerly N-treated plots than in controls. The abundance of Hylocomium splendens (Hedw.) Schimp., the most common bryophyte under normal N conditions, showed a contrasting pattern, with less abundance in the formerly N-treated plots than in controls. Sporocarp production of N-sensitive mycorrhizal fungi was lower in the formerly N-treated plots. No difference in plant species composition was noticed for vascular plants. 4 These results contrast with other studies that have interpreted reduced N leakage and nutrient levels in trees after decreased N input as a rapid ecosystem recovery. The present study suggests that the time needed for recovery of the ecosystem biota may be substantial in originally N-limited ecosystems.},
	language = {en},
	number = {4},
	urldate = {2021-11-02},
	journal = {Functional Ecology},
	author = {Strengbom, J. and Nordin, A. and Näsholm, T. and Ericson, L.},
	year = {2001},
	note = {\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.0269-8463.2001.00538.x},
	keywords = {Critical load, mycorrhizal fungi, vegetational composition},
	pages = {451--457},
}

1 Ecosystem recovery after decreased input of nitrogen was examined in two different fertilization experiments where the fertilization had been terminated for 9 and 47 years, respectively. 2 The species composition of the understorey vegetation showed no signs of recovery 9 years after the fertilization was terminated. Increased sporocarp production of mycorrhizal fungi was seen on formerly fertilized plots compared with plots still receiving N, but the species composition showed large differences compared to control plots. 3 In the second experiment, examined 47 years after termination of fertilization, N favoured bryophytes such as Brachythecium reflexum (Starke) Schimp., Plagiothecium denticulatum (Hedw.) Schimp. and the leaf-parasitic fungus Valdensia heterodoxa Peyronel (attacking Vaccinium myrtillus L.) was more abundant in the formerly N-treated plots than in controls. The abundance of Hylocomium splendens (Hedw.) Schimp., the most common bryophyte under normal N conditions, showed a contrasting pattern, with less abundance in the formerly N-treated plots than in controls. Sporocarp production of N-sensitive mycorrhizal fungi was lower in the formerly N-treated plots. No difference in plant species composition was noticed for vascular plants. 4 These results contrast with other studies that have interpreted reduced N leakage and nutrient levels in trees after decreased N input as a rapid ecosystem recovery. The present study suggests that the time needed for recovery of the ecosystem biota may be substantial in originally N-limited ecosystems.

@article{nordin_soil_2001,
	title = {Soil nitrogen form and plant nitrogen uptake along a boreal forest productivity gradient},
	volume = {129},
	issn = {1432-1939},
	url = {https://doi.org/10.1007/s004420100698},
	doi = {10.1007/s004420100698},
	abstract = {We present results from a study of soil solution concentrations of ammonium (NH4+), nitrate (NO3–), and amino acid N over one growing season along a local 90-m-long plant productivity gradient in a boreal forest. Three forest types are found along the gradient: an ericaceous dwarf-shrub type between 0 and 40 m, a low-herb type between 40 and 80 m, and a tall-herb type at 90 m. Soil sampling of the mor layer was performed in June, July, August and October in the three forest types. In addition, plant uptake of NH4+, NO3– and the amino acid glycine was investigated. A mixture of the three N forms was injected into the soil; one N form at a time was labeled with 15N, and in the case of glycine also with 13C. In the dwarf-shrub forest, where plant productivity was low, the soil N pool was strongly dominated by amino acid N. There, plants took up more NH4+ than NO3–. Glycine uptake did not differ significantly from either NH4+ or NO3– uptake. Along the gradient, soil concentrations of NH4+ and NO3– increased, as did plant productivity. In the low-herb forest NH4+ comprised a major portion of the soil N pool, and plants took up more NH4+ than NO3– or glycine. In the tall-herb forest, NO3– was as abundant as NH4+, and together these two N forms dominated the soil N pool. Here, plants took up nearly equal amounts of NO3– and NH4+, and this uptake exceeded that of glycine severalfold. Apart from the overall preference for NH4+ that plants exhibited throughout the gradient, the results show a correlation between soil concentrations of amino acids and NO3– and plant preferences for these N forms.},
	language = {en},
	number = {1},
	urldate = {2021-11-02},
	journal = {Oecologia},
	author = {Nordin, Annika and Högberg, Peter and Näsholm, Torgny},
	month = sep,
	year = {2001},
	pages = {125--132},
}

We present results from a study of soil solution concentrations of ammonium (NH4+), nitrate (NO3–), and amino acid N over one growing season along a local 90-m-long plant productivity gradient in a boreal forest. Three forest types are found along the gradient: an ericaceous dwarf-shrub type between 0 and 40 m, a low-herb type between 40 and 80 m, and a tall-herb type at 90 m. Soil sampling of the mor layer was performed in June, July, August and October in the three forest types. In addition, plant uptake of NH4+, NO3– and the amino acid glycine was investigated. A mixture of the three N forms was injected into the soil; one N form at a time was labeled with 15N, and in the case of glycine also with 13C. In the dwarf-shrub forest, where plant productivity was low, the soil N pool was strongly dominated by amino acid N. There, plants took up more NH4+ than NO3–. Glycine uptake did not differ significantly from either NH4+ or NO3– uptake. Along the gradient, soil concentrations of NH4+ and NO3– increased, as did plant productivity. In the low-herb forest NH4+ comprised a major portion of the soil N pool, and plants took up more NH4+ than NO3– or glycine. In the tall-herb forest, NO3– was as abundant as NH4+, and together these two N forms dominated the soil N pool. Here, plants took up nearly equal amounts of NO3– and NH4+, and this uptake exceeded that of glycine severalfold. Apart from the overall preference for NH4+ that plants exhibited throughout the gradient, the results show a correlation between soil concentrations of amino acids and NO3– and plant preferences for these N forms.

@article{nordin_amino_2000,
	title = {Amino acid accumulation and growth of {Sphagnum} under different levels of {N} deposition},
	volume = {7},
	issn = {1195-6860},
	url = {https://doi.org/10.1080/11956860.2000.11682619},
	doi = {10.1080/11956860.2000.11682619},
	abstract = {Nitrogen (N) is a critical nutrient for Sphagnum mosses dominating mire ecosystems. We simulated N deposition by adding doses of NH4NO3 (0, 1, 3, 5 and 10 g m−2 yr−1) to two Swedish mires with different levels of background atmospheric N deposition, i.e., on Luttumyren in central Sweden 0.3-0.4 g N m−2 yr−1 and 0.7-1.1 g N m−2 yr−1 on Åkhultmyren in south Sweden. After two years of NH4NO3 additions, free amino acid concentrations of S. fuscum, S. magellanicum and S. rubellum from the two mires were analyzed and length growth of the mosses were measured. N additions increased amino acid concentrations in Sphagnum capitula, whereas it decreased Sphagnum length growth. In general, we found that when Sphagnum amino acid N concentrations exceeded 2.0 mg amino acid N g−1 dry mass, Sphagnum length growth was reduced. The decreased growth did not explain the variation in amino acid concentrations. Hence, increased Sphagnum N assimilation in N treated plots was most likely the factor causing tissue amino acid concentrations to increase. Significant differences among control plots between the two mires in Sphagnum total amino acid N concentrations did not occur. Total amino acid N concentrations of Sphagnum are thus not sensitive enough to reflect differences in N deposition rates when they are below 1.0 g m−2 yr−1.},
	number = {4},
	urldate = {2021-11-08},
	journal = {Écoscience},
	author = {Nordin, Annika and Gunnarsson, Urban},
	month = jan,
	year = {2000},
	note = {Publisher: Taylor \& Francis
\_eprint: https://doi.org/10.1080/11956860.2000.11682619},
	keywords = {Acides aminés, Amino acids, Croissance, Déposition atmosphérique azotée, Growth, N deposition, Sphagnum, Sphaigne},
	pages = {474--480},
}

Nitrogen (N) is a critical nutrient for Sphagnum mosses dominating mire ecosystems. We simulated N deposition by adding doses of NH4NO3 (0, 1, 3, 5 and 10 g m−2 yr−1) to two Swedish mires with different levels of background atmospheric N deposition, i.e., on Luttumyren in central Sweden 0.3-0.4 g N m−2 yr−1 and 0.7-1.1 g N m−2 yr−1 on Åkhultmyren in south Sweden. After two years of NH4NO3 additions, free amino acid concentrations of S. fuscum, S. magellanicum and S. rubellum from the two mires were analyzed and length growth of the mosses were measured. N additions increased amino acid concentrations in Sphagnum capitula, whereas it decreased Sphagnum length growth. In general, we found that when Sphagnum amino acid N concentrations exceeded 2.0 mg amino acid N g−1 dry mass, Sphagnum length growth was reduced. The decreased growth did not explain the variation in amino acid concentrations. Hence, increased Sphagnum N assimilation in N treated plots was most likely the factor causing tissue amino acid concentrations to increase. Significant differences among control plots between the two mires in Sphagnum total amino acid N concentrations did not occur. Total amino acid N concentrations of Sphagnum are thus not sensitive enough to reflect differences in N deposition rates when they are below 1.0 g m−2 yr−1.