{"type": "FeatureCollection", "features": [{"id": "10.1007/pl00008869", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-23T16:14:20Z", "type": "Journal Article", "created": "2006-04-10", "title": "Combined Effects Of Atmospheric Co2 And N Availability On The Belowground Carbon And Nitrogen Dynamics Of Aspen Mesocosms", "description": "It is uncertain whether elevated atmospheric CO2 will increase C storage in terrestrial ecosystems without concomitant increases in plant access to N. Elevated CO2 may alter microbial activities that regulate soil N availability by changing the amount or composition of organic substrates produced by roots. Our objective was to determine the potential for elevated CO2 to change N availability in an experimental plant-soil system by affecting the acquisition of root-derived C by soil microbes. We grew Populus tremuloides (trembling aspen) cuttings for 2 years under two levels of atmospheric CO2 (36.7 and 71.5 Pa) and at two levels of soil N (210 and 970 \u00b5g N g-1). Ambient and twice-ambient CO2 concentrations were applied using open-top chambers, and soil N availability was manipulated by mixing soils differing in organic N content. From June to October of the second growing season, we measured midday rates of soil respiration. In August, we pulse-labeled plants with 14CO2 and measured soil 14CO2 respiration and the 14C contents of plants, soils, and microorganisms after a 6-day chase period. In conjunction with the August radio-labeling and again in October, we used 15N pool dilution techniques to measure in situ rates of gross N mineralization, N immobilization by microbes, and plant N uptake. At both levels of soil N availability, elevated CO2 significantly increased whole-plant and root biomass, and marginally increased whole-plant N capital. Significant increases in soil respiration were closely linked to increases in root biomass under elevated CO2. CO2 enrichment had no significant effect on the allometric distribution of biomass or 14C among plant components, total 14C allocation belowground, or cumulative (6-day) 14CO2 soil respiration. Elevated CO2 significantly increased microbial 14C contents, indicating greater availability of microbial substrates derived from roots. The near doubling of microbial 14C contents at elevated CO2 was a relatively small quantitative change in the belowground C cycle of our experimental system, but represents an ecologically significant effect on the dynamics of microbial growth. Rates of plant N uptake during both 6-day periods in August and October were significantly greater at elevated CO2, and were closely related to fine-root biomass. Gross N mineralization was not affected by elevated CO2. Despite significantly greater rates of N immobilization under elevated CO2, standing pools of microbial N were not affected by elevated CO2, suggesting that N was cycling through microbes more rapidly. Our results contained elements of both positive and negative feedback hypotheses, and may be most relevant to young, aggrading ecosystems, where soil resources are not yet fully exploited by plant roots. If the turnover of microbial N increases, higher rates of N immobilization may not decrease N availability to plants under elevated CO2.", "keywords": ["0106 biological sciences", "root-: biomass-", "Ecology and Evolutionary Biology", "nitrogen-fixation", "Environmental-Sciences)", "01 natural sciences", "nitrogen", "biomass-", "nitrogen-cycle", "nitrogen-", "Microorganisms-", "carbon-14", "124-38-9: CARBON DIOXIDE", "C Cycle", "Spermatophytes-", "Spermatophyta-", "Key Words Atmospheric CO2", "Cellular and Developmental Biology", "Populus Tremuloides Michx", "2. Zero hunger", "carbon-dioxide: atmospheric-", "plant-nutrition", "Climatology- (Environmental-Sciences)", "Angiosperms-", "Angiospermae-", "Plants-", "Natural Resources and Environment", "04 agricultural and veterinary sciences", "global-climate-change", "microbe- (Microorganisms-)", "7727-37-9: NITROGEN", "chemical-composition", "carbon-sequestration", "mineral-uptake", "soil-biology", "Science", "Vascular-Plants", "poplars-", "respiration-", "carbon-dioxide-enrichment", "carbon-dioxide", "Populus-tremuloides [trembling-aspen] (Salicaceae-)", "carbon-cycle", "Health Sciences", "Salicaceae-: Dicotyledones-", "soil-respiration", "content", "Plantae-", "14762-75-5: CARBON-14", "mineralization-", "Molecular", "forest-soils", "15. Life on land", "Rhizodeposition", "soil-flora", "N Cycle", "13. Climate action", "cuttings-", "roots-", "Legacy", "Terrestrial-Ecology (Ecology-", "0401 agriculture", " forestry", " and fisheries", "Dicots-", "ecosystems-"], "contacts": [{"organization": "Mikan, Carl J., Zak, Donald R., Kubiske, Mark E., Pregitzer, Kurt S.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1007/pl00008869"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Oecologia", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/pl00008869", "name": "item", "description": "10.1007/pl00008869", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/pl00008869"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2000-08-23T00:00:00Z"}}, {"id": "10.1007/s00267-003-9139-9", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-23T16:14:22Z", "type": "Journal Article", "created": "2004-03-19", "description": "We collected soil samples from 27 study sites across North Central United States to compare the soil carbon of short rotation poplar plantations to adjacent agricultural crops and woodlots. Soil organic carbon (SOC) ranged from 20 to more than 160 Mg/ha across the sampled sites. Lowest SOC levels were found in uplands and highest levels in riparian soils. We attributed differences in bulk density and SOC among cover types to the inclusion of woodlot soils in the analysis. Paired comparison found few differences between poplar and agricultural crops. Sites with significant comparisons varied in magnitude and direction. Relatively greater SOC was often observed in poplar when native soil carbon was low, but there were important exceptions. Woodlots consistently contained greater SOC than the other crops, especially at depth. We observed little difference between paired poplar and switchgrass, both promising bioenergy crops. There was no evidence of changes in poplar SOC relative to adjacent agricultural soils when considered for stand ages up to 12 years. Highly variable native SOC levels and subtle changes over time make verification of soil carbon sequestration among land cover types difficult. In addition to soil carbon storage potential, it is therefore important to consider opportunities offered by long-term sequestration of carbon in solid wood products and carbon-offset through production of bioenergy crops. Furthermore, short rotation poplars and switchgrass offer additional carbon sequestration and other environmental benefits such as soil erosion control, runoff abatement, and wildlife habitat improvement.", "keywords": ["Greenhouse Effect", "2. Zero hunger", "Carbon Sequestration", "Fossil Fuels", "Switchgrass", "Rotation", "Climate Change", "Crops", "04 agricultural and veterinary sciences", "Carbon Dioxide", "15. Life on land", "Soils Carbon Sequestration", "7. Clean energy", "Carbon", "Manufacturing", "60 Applied Life Sciences", "Hybrid Poplar", "Poplars", "Cements", "Soil Bulk Density", "0401 agriculture", " forestry", " and fisheries", "Bioenergy", "Biomass"]}, "links": [{"href": "https://doi.org/10.1007/s00267-003-9139-9"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Environmental%20Management", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/s00267-003-9139-9", "name": "item", "description": "10.1007/s00267-003-9139-9", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/s00267-003-9139-9"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2004-03-04T00:00:00Z"}}, {"id": "10.1023/a:1004518730970", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-23T16:17:18Z", "type": "Journal Article", "created": "2002-12-21", "description": "Elevated atmospheric CO2 has the potential to change below-ground nutrient cycling and thereby alter the soil-atmosphere exchange of biogenic trace gases. We measured fluxes of CH4 and N2O in trembling aspen (Populus tremuloides Michx.) stands grown in open-top chambers under ambient and twice-ambient CO2 concentrations crossed with \u2018high\u2019 and low soil-N conditions.", "keywords": ["measurement-", "nitrous-oxide", "flux-", "Vascular-Plants", "poplars-", "carbon-dioxide-enrichment", "photosynthesis-", "Nutrition-", "carbon-dioxide: atmospheric-concentration", "stand-growth", "nitrogen-cycle", "michigan-", "methane-: flux-", "soil-", "nitrogen-", "Populus-tremuloides [aspen-] (Salicaceae-)", "carbon-cycle", "methane-production", "soil-fertility", "Salicaceae-: Dicotyledones-", "populus-tremuloides", "cycling-", "Spermatophytes-", "Spermatophyta-", "Plantae-", "biological-activity-in-soil", "Climatology- (Environmental-Sciences)", "Angiosperms-", "Angiospermae-", "Plants-", "gases-", "oxidation-", "forest-soils", "methane-", "04 agricultural and veterinary sciences", "GLOBAL-ECOLOGY", "15. Life on land", "enzyme-activity", "gas-exchange", "nitrous-oxide: emission-", "soil-water", "13. Climate action", "denitrification-", "0401 agriculture", " forestry", " and fisheries", "soil-bacteria", "Dicots-", "efflux-"]}, "links": [{"href": "https://doi.org/10.1023/a:1004518730970"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Plant%20and%20Soil", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1023/a:1004518730970", "name": "item", "description": "10.1023/a:1004518730970", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1023/a:1004518730970"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1999-02-01T00:00:00Z"}}, {"id": "10.2307/2640985", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-23T16:20:18Z", "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. Clean water", "metabolism-", "soil-N transformations", "transformation-", "substrates-", "7727-37-9: NITROGEN", "atmosphere-", "elevated atmospheric", "570", "nitrification-", "nitrogen immobilization", "Science", "Vascular-Plants", "poplars-", "phospholipid fatty acids (PFLAs)", "carbon-dioxide", "growth-", "soil-microbial-community-composition", "Salicaceae-: Dicotyledones-", "microbial-flora", "Populus tremuloides", "Plantae-", "organic-matter", "consortia-", "0105 earth and related environmental sciences", "communities-", "ecosystem", "analysis-", "atmospheric CO2 and soil-N availability", "soil-availability", "mineralization-", "carbon dioxide", "fatty-acids", "15. Life on land", "substrate-input", "Populus-tremuloides (Salicaceae-)", "13. 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": "2026-05-23T16:21:05Z", "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": "<p> 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 </p>", "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=Poplars&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=Poplars&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=Poplars&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Poplars&offset=5", "hreflang": "en-US"}], "numberMatched": 5, "numberReturned": 5, "distributedFeatures": [], "timeStamp": "2026-05-25T15:10:57.581385Z"}