Herbivores can exert major controls over biogeochemical cycling. As invertebrates are highly sensitive to temperature shifts (ectothermal), the abundances of insects in high\uffe2\uff80\uff90latitude systems, where climate warming is rapid, is expected to increase. In subarctic mountain birch forests, research has focussed on geometrid moth outbreaks, while the contribution of background insect herbivory (BIH) to elemental cycling is poorly constrained. In northern Sweden, we estimated BIH along 9 elevational gradients distributed across a gradient in regional elevation, temperature, and precipitation to allow evaluation of consistency in local versus regional variation. We converted foliar loss via BIH to fluxes of C, nitrogen (N), and phosphorus (P) from the birch canopy to the soil to compare with other relevant soil inputs of the same elements and assessed different abiotic and biotic drivers of the observed variability. We found that leaf area loss due to BIH was ~1.6% on average. This is comparable to estimates from tundra, but considerably lower than ecosystems at lower latitudes. The C, N, and P fluxes from canopy to soil associated with BIH were 1\uffe2\uff80\uff932 orders of magnitude lower than the soil input from senesced litter and external nutrient sources such as biological N fixation, atmospheric deposition of N, and P weathering estimated from the literature. Despite the minor contribution to overall elemental cycling in subarctic birch forests, the higher quality and earlier timing of the input of herbivore deposits to soils compared to senesced litter may make this contribution disproportionally important for various ecosystem functions. BIH increased significantly with leaf N content as well as local elevation along each transect, yet showed no significant relationship with temperature or humidity, nor the commonly used temperature proxy, absolute elevation. The lack of consistency between the local and regional elevational trends calls for caution when using elevation gradients as climate proxies.Insect herbivores play important roles in shaping many ecosystem processes, but how climate change will alter the effects of insect herbivory are poorly understood. To address this knowledge gap, we quantified for the first time how insect frass and cadavers affected leaf litter decomposition rates and nutrient release along a highly constrained 4.3\uffc2\uffb0C mean annual temperature (MAT) gradient in a Hawaiian montane tropical wet forest. We constructed litterbags of standardized locally sourced leaf litter, with some amended with insect frass + cadavers to produce treatments designed to simulate ambient (Control\uffc2\uffa0=\uffc2\uffa0no amendment), moderate (Amended\uffe2\uff80\uff90Low\uffc2\uffa0=\uffc2\uffa02\uffe2\uff80\uff89\uffc3\uff97\uffe2\uff80\uff89Control level), or severe (Amended\uffe2\uff80\uff90High\uffc2\uffa0=\uffc2\uffa011\uffe2\uff80\uff89\uffc3\uff97\uffe2\uff80\uff89Control level) insect outbreak events. Multiple sets of these litterbags were deployed across the MAT gradient, with individual litterbags collected periodically over one\uffe2\uff80\uff89year to assess how rising MAT altered the effects of insect deposits on litter decomposition rates and nitrogen (N) release. Increased MAT and insect inputs additively increased litter decomposition rates and N immobilization rates, with effects being stronger for Amended\uffe2\uff80\uff90High litterbags. However, the apparent temperature sensitivity (Q10) of litter decomposition was not clearly affected by amendments. The effects of adding insect deposits in this study operated differently than the slower litter decomposition and greater N mobilization rates often observed in experiments which use chemical fertilizers (e.g., urea, ammonium nitrate). Further research is required to understand mechanistic differences between amendment types. Potential increases in outbreak\uffe2\uff80\uff90related herbivore deposits coupled with climate warming will accelerate litter decomposition and nutrient cycling rates with short\uffe2\uff80\uff90term consequences for nutrient cycling and carbon storage in tropical montane wet forests.Plant community composition is affected by a wide array of soil organisms with diverse feeding modes and functions. Former studies dealt with the high diversity and complexity of soil communities by focusing on particular functional groups in isolation, by grouping soil organisms into body size classes or by using whole communities from different origins. Our approach was to investigate both the individual and the interaction effects of highly abundant soil organisms (microorganisms, nematodes and earthworms) to evaluate their impacts on grassland plant communities. Earthworms increased total plant community biomass by stimulating root growth. Nematodes reduced the biomass of grasses, but this effect was alleviated by the presence of earthworms. Non\uffe2\uff80\uff90leguminous forb biomass increased in the presence of nematodes, probably due to an alleviation of the competitive strength of grasses by nematodes. Microorganisms reduced the diversity and evenness of the plant community, but only in the absence of earthworms. Legume biomass was not affected by soil organisms, butLotus corniculatusflowered earlier in the presence of microorganisms and the number of flowers decreased in the presence of nematodes. The results indicate that earthworms have a profound impact on the structure of grassland plant communities by counterbalancing the negative effects of plant\uffe2\uff80\uff90feeding nematodes on grasses and by conserving the evenness of the plant community. We propose that interacting effects of functionally dissimilar soil organisms on plant community performance have to be taken into account in future studies, since individual effects of soil organism groups may cancel out each other in functionally diverse soil communities.
", "keywords": ["2. Zero hunger", "0106 biological sciences", "0301 basic medicine", "productivity", "microbial biomass", "ground insect herbivory", "early succession", "15. Life on land", "determinant", "01 natural sciences", "03 medical and health sciences", "lumbricidae", "soil food-web", "community structure", "grassland", "performance"]}, "links": [{"href": "https://doi.org/10.1111/j.0030-1299.2008.16333.x"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Oikos", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/j.0030-1299.2008.16333.x", "name": "item", "description": "10.1111/j.0030-1299.2008.16333.x", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/j.0030-1299.2008.16333.x"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2008-04-28T00:00:00Z"}}, {"id": "10.3389/fpls.2020.558979", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-22T16:19:15Z", "type": "Journal Article", "created": "2020-10-27", "title": "Insect Herbivory Strongly Modifies Mountain Birch Volatile Emissions", "description": "Insect herbivory is known to augment emissions of biogenic volatile organic compounds (BVOCs). Yet few studies have quantified BVOC responses to insect herbivory in natural populations in pan-Arctic regions. Here, we assess how quantitative and qualitative BVOC emissions change with increasing herbivore feeding intensity in the Subarctic mountain birch (Betula pubescens var pumila (L.)) forest. We conducted three field experiments in which we manipulated the larval density of geometrid moths (Operophtera brumata and Epirrita autumnata), on branches of mountain birch and measured BVOC emissions using the branch enclosure method and gas chromatography-mass spectrometry. Our study showed that herbivory significantly increased BVOC emissions from the branches damaged by larvae. BVOC emissions increased due to insect herbivory at relatively low larvae densities, causing up to 10% of leaf area loss. Insect herbivory also changed the blend composition of BVOCs, with damaged plants producing less intercorrelated BVOC blends than undamaged ones. Our results provide a quantitative understanding of the relationship between the severity of insect herbivore damage and emissions of BVOCs at larvae densities corresponding to background herbivory levels in the Subarctic mountain birch. The results have important and practical implications for modeling induced and constitutive BVOC emissions and their feedbacks to atmospheric chemistry.", "keywords": ["0301 basic medicine", "0303 health sciences", "VDP::Zoologiske og botaniske fag: 480", "insect herbivory", "Plant culture", "Plant Science", "15. Life on land", "geometrid moth", "SB1-1110", "03 medical and health sciences", "biotic stress", "mountain birch", "stress severity", "13. Climate action", "volatile organic compounds", "11. Sustainability", "arctic", "VDP::Zoology and botany: 480"]}, "links": [{"href": "https://doi.org/10.3389/fpls.2020.558979"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Frontiers%20in%20Plant%20Science", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.3389/fpls.2020.558979", "name": "item", "description": "10.3389/fpls.2020.558979", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.3389/fpls.2020.558979"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2020-10-27T00:00:00Z"}}, {"id": "10.5061/dryad.p5hqbzkqg", "type": "Feature", "geometry": null, "properties": {"license": "unspecified", "updated": "2026-09-22T16:19:47Z", "type": "Dataset", "title": "Data from: Living, dead, and absent trees - How do moth outbreaks shape small-scale patterns of soil organic matter stocks and dynamics at the Subarctic mountain birch treeline?", "description": "unspecifiedSee ReadMe file.", "keywords": ["13. Climate action", "Soil organic carbon stocks", "soil organic matter", "insect herbivory", "Soil respiration", "15. Life on land", "priming effects", "Soil carbon"], "contacts": [{"organization": "Meyer, Nele, Xu, Yi, Karjalainen, Katri, Adamczyk, Sylwia, Biasi, Christina, van Delden, Lona, Martin, Angela, Mganga, Kevin, Myller, Kristiina, Sieti\u00f6, Outi-Maaria, Suominen, Otso, Karhu, Kristiina,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.5061/dryad.p5hqbzkqg"}, {"rel": "self", "type": "application/geo+json", "title": "10.5061/dryad.p5hqbzkqg", "name": "item", "description": "10.5061/dryad.p5hqbzkqg", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.5061/dryad.p5hqbzkqg"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2021-10-19T00:00:00Z"}}, {"id": "3089242097", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-22T16:23:01Z", "type": "Journal Article", "created": "2020-09-22", "title": "Background insect herbivory increases with local elevation but makes minor contribution to element cycling along natural gradients in the Subarctic", "description": "AbstractHerbivores can exert major controls over biogeochemical cycling. As invertebrates are highly sensitive to temperature shifts (ectothermal), the abundances of insects in high\uffe2\uff80\uff90latitude systems, where climate warming is rapid, is expected to increase. In subarctic mountain birch forests, research has focussed on geometrid moth outbreaks, while the contribution of background insect herbivory (BIH) to elemental cycling is poorly constrained. In northern Sweden, we estimated BIH along 9 elevational gradients distributed across a gradient in regional elevation, temperature, and precipitation to allow evaluation of consistency in local versus regional variation. We converted foliar loss via BIH to fluxes of C, nitrogen (N), and phosphorus (P) from the birch canopy to the soil to compare with other relevant soil inputs of the same elements and assessed different abiotic and biotic drivers of the observed variability. We found that leaf area loss due to BIH was ~1.6% on average. This is comparable to estimates from tundra, but considerably lower than ecosystems at lower latitudes. The C, N, and P fluxes from canopy to soil associated with BIH were 1\uffe2\uff80\uff932 orders of magnitude lower than the soil input from senesced litter and external nutrient sources such as biological N fixation, atmospheric deposition of N, and P weathering estimated from the literature. Despite the minor contribution to overall elemental cycling in subarctic birch forests, the higher quality and earlier timing of the input of herbivore deposits to soils compared to senesced litter may make this contribution disproportionally important for various ecosystem functions. BIH increased significantly with leaf N content as well as local elevation along each transect, yet showed no significant relationship with temperature or humidity, nor the commonly used temperature proxy, absolute elevation. The lack of consistency between the local and regional elevational trends calls for caution when using elevation gradients as climate proxies.Herbivores can exert major controls over biogeochemical cycling. As invertebrates are highly sensitive to temperature shifts (ectothermal), the abundances of insects in high\uffe2\uff80\uff90latitude systems, where climate warming is rapid, is expected to increase. In subarctic mountain birch forests, research has focussed on geometrid moth outbreaks, while the contribution of background insect herbivory (BIH) to elemental cycling is poorly constrained. In northern Sweden, we estimated BIH along 9 elevational gradients distributed across a gradient in regional elevation, temperature, and precipitation to allow evaluation of consistency in local versus regional variation. We converted foliar loss via BIH to fluxes of C, nitrogen (N), and phosphorus (P) from the birch canopy to the soil to compare with other relevant soil inputs of the same elements and assessed different abiotic and biotic drivers of the observed variability. We found that leaf area loss due to BIH was ~1.6% on average. This is comparable to estimates from tundra, but considerably lower than ecosystems at lower latitudes. The C, N, and P fluxes from canopy to soil associated with BIH were 1\uffe2\uff80\uff932 orders of magnitude lower than the soil input from senesced litter and external nutrient sources such as biological N fixation, atmospheric deposition of N, and P weathering estimated from the literature. Despite the minor contribution to overall elemental cycling in subarctic birch forests, the higher quality and earlier timing of the input of herbivore deposits to soils compared to senesced litter may make this contribution disproportionally important for various ecosystem functions. BIH increased significantly with leaf N content as well as local elevation along each transect, yet showed no significant relationship with temperature or humidity, nor the commonly used temperature proxy, absolute elevation. The lack of consistency between the local and regional elevational trends calls for caution when using elevation gradients as climate proxies.Insect herbivores play important roles in shaping many ecosystem processes, but how climate change will alter the effects of insect herbivory are poorly understood. To address this knowledge gap, we quantified for the first time how insect frass and cadavers affected leaf litter decomposition rates and nutrient release along a highly constrained 4.3\uffc2\uffb0C mean annual temperature (MAT) gradient in a Hawaiian montane tropical wet forest. We constructed litterbags of standardized locally sourced leaf litter, with some amended with insect frass + cadavers to produce treatments designed to simulate ambient (Control\uffc2\uffa0=\uffc2\uffa0no amendment), moderate (Amended\uffe2\uff80\uff90Low\uffc2\uffa0=\uffc2\uffa02\uffe2\uff80\uff89\uffc3\uff97\uffe2\uff80\uff89Control level), or severe (Amended\uffe2\uff80\uff90High\uffc2\uffa0=\uffc2\uffa011\uffe2\uff80\uff89\uffc3\uff97\uffe2\uff80\uff89Control level) insect outbreak events. Multiple sets of these litterbags were deployed across the MAT gradient, with individual litterbags collected periodically over one\uffe2\uff80\uff89year to assess how rising MAT altered the effects of insect deposits on litter decomposition rates and nitrogen (N) release. Increased MAT and insect inputs additively increased litter decomposition rates and N immobilization rates, with effects being stronger for Amended\uffe2\uff80\uff90High litterbags. However, the apparent temperature sensitivity (Q10) of litter decomposition was not clearly affected by amendments. The effects of adding insect deposits in this study operated differently than the slower litter decomposition and greater N mobilization rates often observed in experiments which use chemical fertilizers (e.g., urea, ammonium nitrate). Further research is required to understand mechanistic differences between amendment types. Potential increases in outbreak\uffe2\uff80\uff90related herbivore deposits coupled with climate warming will accelerate litter decomposition and nutrient cycling rates with short\uffe2\uff80\uff90term consequences for nutrient cycling and carbon storage in tropical montane wet forests.