1 Five treeline species had low seed germination rates and low survivorship and growth of seedlings when transplanted into Alaskan tundra. Seed germination of all species increased with experimental warming, suggesting that the present treeline may in part result from unsuccessful recruitment under cold conditions.
2 Growth, biomass and survivorship of seedlings of treeline species transplanted into tundra were largely unaffected by experimental warming. However, transplanted seedlings of three species (Betula papyrifera, Picea glauca and Populus tremuloides) grew more when below\uffe2\uff80\uff90ground competition with the extant community was reduced. All three measures of transplant performance were greater in shrub tundra than in the less productive tussock or heath tundra. Establishment of trees in tundra may thus be prevented by low resource availability and competition.
3 Two species (Alnus crispa and Populus balsamifera) had low seed germination and survivorship of germinated seeds; transplants of these species did not respond to the manipulations and lost biomass following transplanting into tundra. Isolated populations of these two species north of the present treeline in arctic Alaska probably became established during mid\uffe2\uff80\uff90Holocene warming rather than in recent times.
4 Of all the species studied here, Picea glauca was the most likely to invade intact upland tundra. Its seeds had the highest germination rates and it was the only species whose seedlings survived subsequently. Furthermore, transplanted seedlings of Picea glauca had relatively high survivorship and positive growth in tundra, especially in treatments that increased air temperature or nutrient availability, two factors likely to increase with climate warming.
", "keywords": ["0106 biological sciences", "nutrient-availability", "air-temperature", "tundra", "-Alaska", "Betulaceae-: Dicotyledones-", "Arctic-tundra", "Coniferopsida-: Gymnospermae-", "natural-regeneration", "Environmental-Sciences)", "growth-", "01 natural sciences", "seedlings-", "Picea-glauca", "Betula-papyrifera", "tundra-", "soil-fertility", "Salicaceae-: Dicotyledones-", "Spermatophyta-", "treelines-", "Plantae-", "USA", "tree-establishment", "resource-availability", "Climatology- (Environmental-Sciences)", "Populus-balsamifera (Salicaceae-): seedling-", "Angiosperms-", "transplanting-", "Angiospermae-", "15. Life on land", "Plant-ecology:-communities", "Populus-balsamifera", "Betula-papyrifera (Betulaceae-): seedling-", "Populus-tremuloides", "climate-", "interspecific-competition", "germination", "Populus-tremuloides (Salicaceae-): seedling-", "Terrestrial-Ecology (Ecology-", "Picea-glauca (Coniferopsida-): seedling-", "Dicots-", "seed-germination", "Alnus-crispa", "plant-competition", "Alnus-crispa (Betulaceae-): seedling-", "survival-", "establishment-"]}, "links": [{"href": "https://doi.org/10.1046/j.1365-2745.1998.00278.x"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Journal%20of%20Ecology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1046/j.1365-2745.1998.00278.x", "name": "item", "description": "10.1046/j.1365-2745.1998.00278.x", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1046/j.1365-2745.1998.00278.x"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1998-06-01T00:00:00Z"}}, {"id": "10.1093/treephys/22.7.435", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:18:20Z", "type": "Journal Article", "created": "2012-01-20", "title": "Responses Of Deciduous Broadleaf Trees To Defoliation In A Co2 Enriched Atmosphere", "description": "Relatively little is known about the implications of atmospheric CO2 enrichment for tree responses to biotic disturbances such as folivory. We examined the combined effects of elevated CO2 concentration ([CO2]) and defoliation on growth and physiology of sugar maple (Acer saccharum Marsh.) and trembling aspen (Populus tremuloides Michx.). Seedlings were planted in the ground in eight open-top chambers. Four chambers were ventilated with CO2-enriched air (ambient + 283 micromol mol-1) and four chambers were supplied with ambient air. After 6 weeks of growth, half of the leaf area was removed on a subset of seedlings of each species in each CO2 treatment. We monitored subsequent biomass gain and allocation, along with leaf gas exchange and chemistry. Defoliation did not significantly affect final seedling biomass in either species or CO2 treatment. Growth recovery following defoliation was associated with increased allocation to leaf mass in maple and a slight enhancement of mean photosynthesis in aspen. Elevated [CO2] did not significantly affect aspen growth, and the observed stimulation of maple growth was significant only in mid-season. Correspondingly, simulated responses of whole-tree photosynthesis to elevated [CO2] were constrained by a decrease in photosynthetic capacity in maple, and were partially offset by reductions in specific leaf area and biomass allocation to foliage in aspen. There was a significant interaction between [CO2] and defoliation on only a few of the measured traits. Thus, the data do not support the hypothesis that atmospheric CO2 enrichment will substantially alter tree responses to folivory. However, our findings do provide further indication that regeneration-stage growth rates of certain temperate tree species may respond only moderately to a near doubling of atmospheric [CO2].", "keywords": ["defoliation-", "0106 biological sciences", "Ecophysiology", "Quaking aspen", "biomass-allocation", "growth-response", "Growth", "Environmental-Sciences)", "01 natural sciences", "plant-composition", "Trees", "biomass-", "Spermatophyta-", "Biomass", "Photosynthesis", "plant-physiology", "defoliation", "Angiospermae-", "leaf-area", "GLOBAL-ECOLOGY", "seedling-growth", "source-sink-relations", "Populus-tremuloides", "gas-exchange", "Populus", "broadleaves-", "deciduous-tree", "forest-trees", "atmosphere-", "trees-", "biomass-production", "Acer saccharum", "Nitrogen", "Carbohydrates", "Acer", "carbon-dioxide-enrichment", "photosynthesis-", "growth-", "species-differences", "seedlings-", "wisconsin-", "Populus tremuloides", "photosynthesis", "Climatic changes", "Carbon Dioxide", "15. Life on land", "Plant Leaves", "leaves-", "Aceraceae-: Dicotyledones-", "Carbon dioxide", "Sugar maple", "Seedlings", "Terrestrial-Ecology (Ecology-", "Acer-saccharum"], "contacts": [{"organization": "Volin, John C., Kruger, Eric L., Lindroth, Richard L.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1093/treephys/22.7.435"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Tree%20Physiology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1093/treephys/22.7.435", "name": "item", "description": "10.1093/treephys/22.7.435", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1093/treephys/22.7.435"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2002-05-01T00:00:00Z"}}, {"id": "10.1139/x78-044", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:19:12Z", "type": "Journal Article", "created": "2007-11-26", "title": "Biomass And Nutrient Distribution In Aspen, Pine, And Spruce Stands On The Same Soil Type In Minnesota", "description": "Vegetation and soils were sampled in adjacent 40-year-old stands of red pine (Pinusresinosa Ait.), jack pine (Pinusbanksiana Lamb.), white spruce (Piceaglauca (Moench.) Voss), and aspen (Populustremuloides Michx., P. grandidentata Michx.) on a very fine sandy loam soil in north-central Minnesota. Total tree biomass was greatest for red pine followed by aspen, spruce, and jack pine. Nutrient weights (N, P, K, Ca, Mg) in the trees were greatest in aspen followed generally by spruce, red pine, and jack pine. Particularly large proportions of biomass and nutrients were found in aspen bark and spruce foliage and branches. Understory biomass contributed less than 1.2% of the total organic matter in the vegetation\uffe2\uff80\uff93soil complex but contributed up to 5.0% of the nutrients. Exchangeable Ca in the surface soil was much lower under aspen and spruce than under the pines. No significant soil differences between species were detected below 36\uffe2\uff80\uff82cm. Harvesting the entire aboveground portion of the tree would remove up to three times more nutrients from the site than would harvesting only the bole.
", "keywords": ["0106 biological sciences", "Yield", "Spermatophyta", "Angiosperms", "Nitrogen", "Sandy Loam", "plant nutrition", "Coniferopsida: Gymnospermae", "Gymnosperms", "magnesium", "Pinus Banksiana", "01 natural sciences", "nitrogen", "Dicots", "forest soils", "temperate zones", "Picea Glauca", "Populus Tremuloides", "nutrients", "Spermatophytes", "Magnesium", "phosphorus", "Plantae", "Pinus Resinosa", "Forest Sciences", "soil types ecological", "calcium", "Vascular Plants", "Salicaceae: Dicotyledones", "potassium", "Populus Grandidentata", "Phosphorus", "Plants", "15. Life on land", "nutrition", "Angiospermae", "Tracheophyta: Plantae", "Potassium", "Calcium"], "contacts": [{"organization": "Alban, David H., Perala, Donald A., Schlaegel, Bryce E.,", "roles": ["creator"]}]}, "links": [{"href": "https://digitalcommons.usu.edu/context/aspen_bib/article/5834/viewcontent/Alban412.pdf"}, {"href": "https://doi.org/10.1139/x78-044"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Canadian%20Journal%20of%20Forest%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1139/x78-044", "name": "item", "description": "10.1139/x78-044", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1139/x78-044"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1978-09-01T00:00:00Z"}}, {"id": "10.1139/x88-221", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:19:13Z", "type": "Journal Article", "created": "2007-12-19", "title": "Biomass And Nutrients In Regenerating Woody Vegetation Following Whole-Tree And Conventional Harvest In A Northern Mixed Forest", "description": "Biomass and nutrient contents of regenerating woody plants and litter fall were measured after a northern mixed conifer\uffe2\uff80\uff93hardwood forest was harvested by conventional and whole-tree methods. Before harvest, the central Ontario study site was occupied by a 95-year-old pine (Pinusresinosa, P. strobus) and aspen (Populustremuloides, P. grandidentata) stand growing on gently rolling, gravel-free outwash sands. Four years after harvest, aspen abundance increased 100-fold in both harvested areas, with higher densities after whole-tree harvest (WTH) (4.1\uffe2\uff80\uff82stems/m2) than after conventional harvest (CH) (2.7\uffe2\uff80\uff82stems/m2). No self-thinning of aspen occurred between 2 and 4 years after harvest. Total aboveground woody biomass accumulated at 2.0\uffe2\uff80\uff82t\uffe2\uff80\uffa2ha\uffe2\uff88\uff921\uffe2\uff80\uffa2year\uffe2\uff88\uff921 in the WTH area and 1.5\uffe2\uff80\uff82t\uffe2\uff80\uffa2ha\uffe2\uff88\uff921\uffe2\uff80\uffa2year\uffe2\uff88\uff921 in the CH area; the preharvest rate was 2.0\uffe2\uff80\uff82t\uffe2\uff80\uffa2ha\uffe2\uff88\uff921\uffe2\uff80\uffa2year\uffe2\uff88\uff921. Peak autumn litter production occurred earlier in the harvested areas than in an adjacent uncut area. Cycling of N and K in litter fall returned to preharvest rates after 4 years. Cycling of Ca in litter fall was lower after WTH than after CH. Vegetation uptake of N and K (litter fall plus woody biomass) in the harvested areas in year 4 exceeded the preharvest value. Increased N accumulation in woody biomass (3.0\uffe2\uff80\uff82kg\uffe2\uff80\uffa2ha\uffe2\uff88\uff921\uffe2\uff80\uffa2year\uffe2\uff88\uff921 before harvest, 10.6\uffe2\uff80\uff82kg\uffe2\uff80\uffa2ha\uffe2\uff88\uff921\uffe2\uff80\uffa2year\uffe2\uff88\uff921 after WTH) would place a relatively greater demand on forest floor N pools in the WTH than in the CH area owing to lack of N input in logging slash. Although WTH did not reduce initial rates of biomass production, Populus spp. had lower concentrations of N, Ca, and Mg in the WTH area than in the CH area. There may be a danger that WTH on less fertile sites in the region will produce dense, unproductive aspen stands with low rates of self-thinning.
", "keywords": ["0106 biological sciences", "Spermatophyta", "Angiosperms", "Broadleaves", "Forest litter", "Microorganisms", "Coniferopsida: Gymnospermae", "Gymnosperms", "01 natural sciences", "logging", "Dicots", "pines", "nutrients", "Spermatophytes", "Natural regeneration", "Plant nutrition", "Plantae", "Forest Sciences", "Vascular Plants", "biomass", "Stand characteristics", "Salicaceae: Dicotyledones", "thinning", "Soil morphology", "Cycling", "Forestry", "Pinus Resinosa Pinus Strobus Populus Tremuloides Populus Grandidentata Forest Biomass Energy Forest Products", "Plants", "15. Life on land", "Conifers", "Angiospermae", "composition", "whole tree logging", "nutrient reserves", "natural thinning", "measurement", "ecology"], "contacts": [{"organization": "Hendrickson, O.Q.", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1139/x88-221"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Canadian%20Journal%20of%20Forest%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1139/x88-221", "name": "item", "description": "10.1139/x88-221", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1139/x88-221"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1988-11-01T00:00:00Z"}}, {"id": "10.1139/x89-213", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:19:13Z", "type": "Journal Article", "created": "2008-01-08", "title": "The Effect Of Wildfire On Soil Chemistry In 4 Forest Types In Interior Alaska", "description": "Soil chemical properties were studied after a wildfire in stands of white spruce (Piceaglauca (Moench) Voss), black spruce (Piceamariana (Mill.) B.S.P.), paper birch (Betulapapyrifera Marsh.), and quaking aspen (Populustremuloides Michx.). Samples of the forest floor and surface 5\uffe2\uff80\uff82cm of mineral soil were collected from burned sites and unburned controls and analyzed soon after the fire. With the exception of soil pH, effects of the fire on soil chemistry differed among the four forest types. Generally, amounts of exchangeable K, Ca, and Mg did not appreciably increase in the forest floor and surface mineral soil except in heavily burned areas in white spruce and black spruce. Fire reduced amounts of N by about 50% in white spruce, aspen, and birch forest floors. In black spruce, quantities of N were slightly higher in heavily burned locations. Forest floor C:N ratios were substantially lower in heavily burned locations in white spruce and black spruce than in unburned controls. Burning did not have a marked influence on supplies of available P in the forest floor, except in heavily burned black spruce, where average amounts were 12.50\uffe2\uff80\uff82g/m2 versus only 0.46\uffe2\uff80\uff82g/m2 in the control. Burning caused more moderate gains in available P in surface mineral soils under aspen and white spruce. We concluded that fire caused marked short-term changes in soil chemistry in the four forest types. How long these changes will persist is unknown.
", "keywords": ["Spermatophyta", "Angiosperms", "PH", "Coniferopsida: Gymnospermae", "Betula Papyrifera", "Gymnosperms", "01 natural sciences", "Dicots", "Picea Mariana", "Picea Glauca", "Populus Tremuloides", "Betulaceae: Dicotyledones", "Spermatophytes", "Magnesium", "Plantae", "Forest Sciences", "0105 earth and related environmental sciences", "Plant Carbon Nitrogen Ratio", "Vascular Plants", "Salicaceae: Dicotyledones", "Phosphorus", "Forestry", "04 agricultural and veterinary sciences", "Plants", "15. Life on land", "Angiospermae", "Potassium", "0401 agriculture", " forestry", " and fisheries", "Calcium"], "contacts": [{"organization": "Dyrness, D.T., Van Cleve, K., Levison, J.D.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1139/x89-213"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Canadian%20Journal%20of%20Forest%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1139/x89-213", "name": "item", "description": "10.1139/x89-213", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1139/x89-213"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1989-11-01T00:00:00Z"}}, {"id": "10.1139/x92-146", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:19:13Z", "type": "Journal Article", "created": "2009-12-18", "title": "Carbon Storage In Lake States Aspen Ecosystems", "description": "Total ecosystem carbon in the soil and vegetation was measured for a range of aspen (Populustremuloides Michx.) ecosystems, including a chronosequence on the same soil ranging in age from 0 to 80 years. Soil carbon stayed relatively constant throughout the stand's life and was not affected by timber harvesting. Changes in ecosystem carbon closely paralleled the changes in standing biomass. Aspen grown on 40-year rotations on good soils will sequester several times as much carbon per year as old-growth forests.
", "keywords": ["Management Options", "0106 biological sciences", "Michigan", "Spermatophyta", "Angiosperms", "Broadleaves", "wisconsin", "aspen", "Minnesota", "01 natural sciences", "Dicots", "forest succession", "Spermatophytes", "Populus tremuloides", "Biomass", "Plantae", "Forest Sciences", "USA", "Vascular Plants", "Salicaceae: Dicotyledones", "carbon", "Rotation Length", "age of trees", "Forestry", "Carbon cycle", "plant succession", "Plants", "Timber Harvest", "forest ecosystem", "carbon storage", "15. Life on land", "Angiospermae", "Chronosequence Soil Carbon", "ecosystems"], "contacts": [{"organization": "Alban, David H., Perala, D.A.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1139/x92-146"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Canadian%20Journal%20of%20Forest%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1139/x92-146", "name": "item", "description": "10.1139/x92-146", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1139/x92-146"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1992-08-01T00:00:00Z"}}, {"id": "10.2307/2656979", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:20:28Z", "type": "Journal Article", "created": "2006-04-21", "title": "Genotypic Variation For Condensed Tannin Production In Trembling Aspen (Populs Tremuloides, Salicaceae) Under Elevated Co2 And In High- And Low-Fertility Soil", "description": "The carbon/nutrient balance hypothesis suggests that leaf carbon to nitrogen ratios influence the synthesis of secondary compounds such as condensed tannins. We studied the effects of rising atmospheric carbon dioxide on carbon to nitrogen ratios and tannin production. Six genotypes of Populus tremuloides were grown under elevated and ambient CO2 partial pressure and high\uffe2\uff80\uff90 and low\uffe2\uff80\uff90fertility soil in field open\uffe2\uff80\uff90top chambers in northern lower Michigan, USA. During the second year of exposure, leaves were harvested three times (June, August, and September) and analyzed for condensed tannin concentration. The carbon/nutrient balance hypothesis was supported overall, with significantly greater leaf tannin concentration at high CO2 and low soil fertility compared to ambient CO2 and high soil fertility. However, some genotypes increased tannin concentration at elevated compared to ambient CO2, while others showed no CO2 response. Performance of lepidopteran leaf miner (Phyllonorycter tremuloidiella) larvae feeding on these plants varied across genotypes, CO2, and fertility treatments. These results suggest that with rising atmospheric CO2, plant secondary compound production may vary within species. This could have consequences for plant\uffe2\uff80\uff93herbivore and plant\uffe2\uff80\uff93microbe interactions and for the evolutionary response of this species to global climate change.
", "keywords": ["0106 biological sciences", "Salicaceae", "genotype", "plant\u2013herbivore interaction", "Phyllonorycter-tremuloidiella", "Quaking aspen", "01 natural sciences", "plant-composition", "tannin", "nitrogen-", "carbon-dioxide: elevation-", "124-38-9: CARBON DIOXIDE", "Spermatophytes-", "Spermatophyta-", "genotypic-variation", "Population-Genetics (Population-Studies)", "2. Zero hunger", "carbon-", "Climatology- (Environmental-Sciences)", "Angiosperms-", "Angiospermae-", "Plants-", "GLOBAL-ECOLOGY", "Populus-tremuloides", "plant-pests", "climate-change", "genetic-variation", "forest-trees", "condensed tannins", "Nitrogen", "Science", "Vascular-Plants", "carbon-dioxide-enrichment", "Nutrition-", "genotypes-", "Phyllonorycter tremuloidiella", "Populus-tremuloides [trembling-aspen] (Salicaceae-)", "soil-fertility", "Populus tremuloides", "Salicaceae-: Dicotyledones-", "Biology", "Plantae-", "global change", "tannins-", "condensed-tannin: production-", "foliage-", "forest-pests", "Tannic acid", "Metabolism-", "Botany", "carbon dioxide", "forest-soils", "15. Life on land", "Carbon", "climate-", "Carbon dioxide", "13. Climate action", "Dicots-", "insect-pests"], "contacts": [{"organization": "Donald R. Zak, Jennifer L Mansfield, Kurt S. Pregitzer, Kurt S. Pregitzer, Peter S. Curtis, Peter S. Curtis,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.2307/2656979"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/American%20Journal%20of%20Botany", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.2307/2656979", "name": "item", "description": "10.2307/2656979", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.2307/2656979"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1999-08-01T00:00:00Z"}}, {"id": "10.2307/2640985", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:20:28Z", "type": "Journal Article", "created": "2006-04-17", "description": "Elevated atmospheric CO2 has the potential to increase the production and alter the chemistry of organic substrates entering soil from plant production, the magnitude of which is constrained by soil-N availability. Because microbial growth in soil is limited by substrate inputs from plant production, we reasoned that changes in the amount and chemistry of these organic substrates could affect the composition of soil microbial com- munities and the cycling of N in soil. We studied microbial community composition and soil-N transformations beneath Populus tremuloides Michx. growing under experimental atmospheric CO2 (35.7 and 70.7 Pa) and soil-N-availability (low N 5 61 ng N\u00b7g 21 \u00b7d 21 and high N 5 319 ng N\u00b7g 21 \u00b7d 21 ) treatments. Atmospheric CO2 concentration was modified in large, open-top chambers, and we altered soil-N availability in open-bottom root boxes by mixing different proportions of A and C horizon material. We used phospholipid fatty-acid analysis to gain insight into microbial community composition and coupled this analysis to measurements of soil-N transformations using 15 N-pool dilution techniques. The infor- mation presented here is part of an integrated experiment designed to elucidate the phys- iological mechanisms controlling the flow of C and N in the plant-soil system. Our ob- jectives were (1) to determine whether changes in plant growth and tissue chemistry alter microbial community composition and soil-N cycling in response to increasing atmospheric CO2 and soil-N availability and (2) to integrate the results of our experiment into a synthesis of elevated atmospheric CO2 and the cycling of C and N in terrestrial ecosystems. After 2.5 growing seasons, microbial biomass, gross N mineralization, microbial im- mobilization, and nitrification (gross and net) were equivalent at ambient and elevated CO2, suggesting that increases in fine-root production and declines in fine-root N concentration were insufficient to alter the influence of native soil organic matter on microbial physiology; this was the case in both low- and high-N soil. Similarly, elevated CO2 did not alter the proportion of bacterial, actinomycetal, or fungal phospholipid fatty acids in low-N or high-N soil, indicating that changes in substrate input from greater plant growth under elevated CO2 did not alter microbial community composition. Our results differ from a substantial number of studies reporting increases and decreases in soil-N cycling under elevated CO 2. From our analysis, it appears that soil-N cycling responds to elevated atmospheric CO 2 in experimental situations where plant roots have fully colonized the soil and root-associated C inputs are sufficient to modify the influence of native soil organic matter on microbial physiology. In young developing ecosystems where plant roots have not fully exploited the soil, microbial metabolism appears to be regulated by relatively large pools of soil organic matter, rather than by the additional input of organic substrates under elevated CO 2.", "keywords": ["measurement-", "soil microorganisms", "Ecology and Evolutionary Biology", "nitrogen-: cycling-", "feedback", "microbial community composition", "techniques-", "Environmental-Sciences)", "01 natural sciences", "litter-plant", "biomass-", "gross and net", "124-38-9: CARBON DIOXIDE", "Spermatophytes-", "cycling-", "soil-organic-matter", "mineralization", "Spermatophyta-", "responses-", "phospholipid-fatty-acids", "2. Zero hunger", "Climatology- (Environmental-Sciences)", "Angiosperms-", "Angiospermae-", "Plants-", "global climate change", "microbial immobilization", "nutrient-", "Soil-Science", "6. 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Climate action", "roots-", "Terrestrial-Ecology (Ecology-", "composition-", "Dicots-", "immobilization-", "seasons-", "ecosystems-"], "contacts": [{"organization": "Zak, Donald R., Pregitzer, Kurt S., Curtis, Peter S., Holmes, William E.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.2307/2640985"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Ecological%20Applications", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.2307/2640985", "name": "item", "description": "10.2307/2640985", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.2307/2640985"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2000-02-01T00:00:00Z"}}, {"id": "10.4141/s98-081", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:21:19Z", "type": "Journal Article", "created": "2011-04-23", "title": "Effects Of Forest Soil Compaction And Organic Matter Removal On Leaf Litter Decomposition In Central British Columbia", "description": "As part of the long-term soil productivity study in central British Columbia, we examined the effect of soil compaction and organic matter removal on trembling aspen (Populus tremuloides Michx.) litter decomposition. We compared three levels of organic matter removal (stem-only, whole-tree harvest, and scalped mineral soil) and two levels of compaction (no compaction and heavy compaction) in a factorial design replicated as blocks on three sites. Whole-tree harvesting significantly increased litter decomposition rates compared to stem-only (by 36%) and scalped (by 41%) treatments. Soil compaction had inconsistent effects on decomposition rates (k) for forest floor and scalped treatments and, overall, did not significantly affect litter decomposition rates. Litter on scalped plots had higher rates of nutrient translocation than litter on forest floors. We found the treatments altered soil heat sums, so changes in temperatures at the soil surface might be partly responsible for the changes in decomposition rates. We could not detect differences in soil mesofauna populations collected from the litter bags, so treatment effects on fauna probably had less influence than microclimate on decomposition rates. The effects of these early changes in litter decomposition on biological productivity will be part of the ongoing long-term soil productivity study. Key words: Litter decomposition, soil compaction, scalping, whole-tree harvest, nutrient translocation
", "keywords": ["0106 biological sciences", "leaf-litter-decomposition: organic-matter-removal", "nutrients-", "Environmental-Sciences)", "01 natural sciences", "harvesting-", "translocation-", "populus-tremuloides", "soil-organic-matter", "Spermatophytes-", "Spermatophyta-", "Angiosperms-", "Angiospermae-", "Plants-", "heat-sums", "04 agricultural and veterinary sciences", "Soil-Science", "British-Columbia (Canada-", "North-America", "Nearctic-region)", "compaction-", "soil-compaction", "decomposition-", "microclimate-", "Vascular-Plants", "poplars-", "forests-", "movement-in-soil", "treatment-", "sustainability-", "Populus-tremuloides [trembling-aspen] (Salicaceae-)", "british-columbia", "Salicaceae-: Dicotyledones-", "land-productivity", "organic-matter", "Plantae-", "forest-litter", "productivity-", "forestry-practices", "forestry-", "mineralization-", "forest-soils", "mineral-soils", "removal-", "15. Life on land", "logging-effects", "Terrestrial-Ecology (Ecology-", "0401 agriculture", " forestry", " and fisheries", "Dicots-", "temperature-", "soil-fauna"], "contacts": [{"organization": "Kranabetter, J.M., Chapman, B.K.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.4141/s98-081"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Canadian%20Journal%20of%20Soil%20Science", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.4141/s98-081", "name": "item", "description": "10.4141/s98-081", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.4141/s98-081"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1999-11-01T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Spermatophyta&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Spermatophyta&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Spermatophyta&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Spermatophyta&offset=13", "hreflang": "en-US"}], "numberMatched": 13, "numberReturned": 13, "distributedFeatures": [], "timeStamp": "2026-05-26T01:57:17.311912Z"}