The effects of atmospheric nitrogen (N) deposition on organic matter decomposition vary with the biochemical characteristics of plant litter. At the ecosystem\uffe2\uff80\uff90scale, net effects are difficult to predict because various soil organic matter (SOM) fractions may respond differentially. We investigated the relationship between SOM chemistry and microbial activity in three northern deciduous forest ecosystems that have been subjected to experimental N addition for 2 years. Extractable dissolved organic carbon (DOC), DOC aromaticity, C\uffe2\uff80\uff83:\uffe2\uff80\uff83N ratio, and functional group distribution, measured by Fourier transform infrared spectra (FTIR), were analyzed for litter and SOM. The largest biochemical changes were found in the sugar maple\uffe2\uff80\uff93basswood (SMBW) and black oak\uffe2\uff80\uff93white oak (BOWO) ecosystems. SMBW litter from the N addition treatment had less aromaticity, higher C\uffe2\uff80\uff83:\uffe2\uff80\uff83N ratios, and lower saturated carbon, lower carbonyl carbon, and higher carboxylates than controls; BOWO litter showed opposite trends, except for carbonyl and carboxylate contents. Litter from the sugar maple\uffe2\uff80\uff93red oak (SMRO) ecosystem had a lower C\uffe2\uff80\uff83:\uffe2\uff80\uff83N ratio, but no change in DOC aromaticity. For SOM, the C\uffe2\uff80\uff83:\uffe2\uff80\uff83N ratio increased with N addition in SMBW and SMRO ecosystems, but decreased in BOWO; N addition did not affect the aromaticity of DOC extracted from mineral soil. All ecosystems showed increases in extractable DOC from both litter and soil in response to N treatment. The biochemical changes are consistent with the divergent microbial responses observed in these systems. Extracellular oxidative enzyme activity has declined in the BOWO and SMRO ecosystems while activity in the SMBW ecosystem, particularly in the litter horizon, has increased. In all systems, enzyme activities associated with the hydrolysis and oxidation of polysaccharides have increased. At the ecosystem scale, the biochemical characteristics of the dominant litter appear to modulate the effects of N deposition on organic matter dynamics.
", "keywords": ["Litter Chemistry", "Geology and Earth Sciences", "13. Climate action", "Soil Organic Matter", "Science", "Ecology and Evolutionary Biology", "0401 agriculture", " forestry", " and fisheries", "Nitrogen Deposition", "04 agricultural and veterinary sciences", "15. Life on land", "Dissolved Organic Matter", "Extracellular Enzyme Activity"]}, "links": [{"href": "https://doi.org/10.1111/j.1365-2486.2005.01001.x"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Global%20Change%20Biology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/j.1365-2486.2005.01001.x", "name": "item", "description": "10.1111/j.1365-2486.2005.01001.x", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/j.1365-2486.2005.01001.x"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2005-07-19T00:00:00Z"}}, {"id": "10.1007/s10533-004-7112-1", "type": "Feature", "geometry": null, "properties": {"updated": "2026-06-23T16:15:18Z", "type": "Journal Article", "created": "2005-11-04", "title": "Extracellular Enzyme Activities And Soil Organic Matter Dynamics For Northern Hardwood Forests Receiving Simulated Nitrogen Deposition", "description": "Anthropogenic nitrogen enrichment alters decomposition processes that control the flux of carbon (C) and nitrogen (N) from soil organic matter (SOM) pools. To link N-driven changes in SOM to microbial responses, we measured the potential activity of several extracellular enzymes involved in SOM degradation at nine experimental sites located in northern Michigan. Each site has three treatment plots (ambient, +30 and +80 kg N ha 1 y 1 ). Litter and soil samples were collected on five dates over the third growing season of N treatment. Phenol oxidase, peroxidase and cellobiohydrolase activities showed significant responses to N additions. In the Acer saccha- rum-Tilia americana ecosystem, oxidative activity was 38% higher in the litter horizon of high N treatment plots, relative to ambient plots, while oxidative activity in mineral soil showed little change. In the A. saccharum-Quercus rubra and Q. velutina-Q. alba ecosystems, oxidative activities declined in both litter (15 and 23%, respectively) and soil (29 and 38%, respectively) in response to high N treatment while cellobiohydrolase activity increased (6 and 39% for litter, 29 and 18% for soil, respectively). Over 3 years, SOM content in the high N plots has decreased in the Acer-Tilia ecosystem and increased in the two Quercus ecosystems, relative to ambient plots. For all three ecosystems, differences in SOM content in relation to N treatment were directly related (r 2 = 0.92) to an enzyme activity factor that included both oxidative and hydrolytic enzyme responses.", "keywords": ["Soil Science & Conservation", "Decomposition", "Science", "Ecology and Evolutionary Biology", "Terrestrial Pollution", "Natural Resources and Environment", "Molecular", "04 agricultural and veterinary sciences", "15. Life on land", "Biochemistry", "Phenol Oxidase", "Geochemistry", "Cellulase", "Soil Organic Matter", "Health Sciences", "0401 agriculture", " forestry", " and fisheries", "Nitrogen Deposition", "Cellular and Developmental Biology", "General", "Extracellular Enzyme Activity", "Geosciences"]}, "links": [{"href": "https://doi.org/10.1007/s10533-004-7112-1"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Biogeochemistry", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/s10533-004-7112-1", "name": "item", "description": "10.1007/s10533-004-7112-1", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/s10533-004-7112-1"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2005-08-01T00:00:00Z"}}, {"id": "10.1007/s10533-015-0157-5", "type": "Feature", "geometry": null, "properties": {"updated": "2026-06-23T16:15:20Z", "type": "Journal Article", "created": "2015-11-14", "title": "Chronic Nitrogen Fertilization And Carbon Sequestration In Grassland Soils: Evidence Of A Microbial Enzyme Link", "description": "Chronic nitrogen (N) fertilization can greatly affect soil carbon (C) sequestration by altering biochemical interactions between plant detritus and soil microbes. In lignin-rich forest soils, chronic N additions tend to increase soil C content partly by decreasing the activity of lignin-degrading enzymes. In cellulose-rich grassland soils it is not clear whether cellulose-degrading enzymes are also inhibited by N additions and what consequences this might have on changes in soil C content. Here we address whether chronic N fertilization has affected (1) the C content of light versus heavier soil fractions, and (2) the activity of four extracellular enzymes including the C-acquiring enzyme \u03b2-1,4-glucosidase (BG; necessary for cellulose hydrolysis). We found that 19\u00a0years of chronic N-only addition to permanent grassland have significantly increased soil C sequestration in heavy but not in light soil density fractions, and this C accrual was associated with a significant increase (and not decrease) of BG activity. Chronic N fertilization may increase BG activity because greater N availability reduces root C:N ratios thus increasing microbial demand for C, which is met by C inputs from enhanced root C pools in N-only fertilized soils. However, BG activity and total root mass strongly decreased in high pH soils under the application of lime (i.e. CaCO3), which reduced the ability of these organo-mineral soils to gain more C per units of N added. Our study is the first to show a potential \u2018enzyme link\u2019 between (1) long-term additions of inorganic N to grassland soils, and (2) the greater C content of organo-mineral soil fractions. Our new hypothesis is that the \u2018enzyme link\u2019 occurs because (a) BG activity is stimulated by increased microbial C demand relative to N under chronic fertilization, and (b) increased BG activity causes more C from roots and from microbial metabolites to accumulate and stabilize into organo-mineral C fractions. We suggest that any combination of management practices that can influence the BG \u2018enzyme link\u2019 will have far reaching implications for long-term C sequestration in grassland soils.", "keywords": ["DECOMPOSITION", "DYNAMICS", "570", "\u03b2-1", "4-Glucosidase", "/dk/atira/pure/subjectarea/asjc/2300/2304", "NUTRIENT RELEASE", "Environmental Sciences & Ecology", "Root C:N ratio", "Extracellular enzyme activity", "LITTER DECAY", "FOREST ECOSYSTEMS", "0399 Other Chemical Sciences", "0402 Geochemistry", "Environmental Chemistry", "Geosciences", " Multidisciplinary", "beta-1", "4-Glucosidase", "Earth-Surface Processes", "Water Science and Technology", "2. Zero hunger", "Multidisciplinary", "Science & Technology", "/dk/atira/pure/subjectarea/asjc/1900/1904", "Geology", "sequestration", "Agronomy & Agriculture", "04 agricultural and veterinary sciences", "15. Life on land", "Soil carbon", "N DEPOSITION", "ORGANIC-MATTER", "PHOSPHORUS", "Fertilization", "Physical Sciences", "N ratio [Root C]", "0401 agriculture", " forestry", " and fisheries", "Soil carbon sequestration", "Liming", "TURNOVER", "Life Sciences & Biomedicine", "Geosciences", "/dk/atira/pure/subjectarea/asjc/2300/2312", "Environmental Sciences", "RESPONSES"]}, "links": [{"href": "https://doi.org/10.1007/s10533-015-0157-5"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Biogeochemistry", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/s10533-015-0157-5", "name": "item", "description": "10.1007/s10533-015-0157-5", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/s10533-015-0157-5"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2015-11-14T00:00:00Z"}}, {"id": "10.1111/1365-2435.14178", "type": "Feature", "geometry": null, "properties": {"updated": "2026-06-23T16:19:17Z", "type": "Journal Article", "created": "2022-09-10", "title": "Nitrogen loading enhances phosphorus limitation in terrestrial ecosystems with implications for soil carbon cycling", "description": "Abstract
Increased human\uffe2\uff80\uff90derived nitrogen (N) loading in terrestrial ecosystems has caused widespread ecosystem\uffe2\uff80\uff90level phosphorus (P) limitation. In response, plants and soil micro\uffe2\uff80\uff90organisms adopt a series of P\uffe2\uff80\uff90acquisition strategies to offset N loading\uffe2\uff80\uff90induced P limitation. Many of these strategies impose costs on carbon (C) allocation by plants and soil micro\uffe2\uff80\uff90organisms; however, it remains unclear how P\uffe2\uff80\uff90acquisition strategies affect soil C cycling. Herein, we review the literature on the effects of N loading on P limitation and outline a conceptual overview of how plant and microbial P\uffe2\uff80\uff90acquisition strategies may affect soil organic carbon (SOC) stabilization and decomposition in terrestrial ecosystems.
Excessive input of N significantly enhances plant biomass production, soil acidification, and produces plant litterfall with high N/P ratios, which can aggravate ecosystem\uffe2\uff80\uff90level P limitation.
Long\uffe2\uff80\uff90term N loading can cause plants and soil micro\uffe2\uff80\uff90organisms to alter their functional traits to increase P acquisition. Plants can release carboxylate exudates and phosphatases, modify root morphological traits, facilitate the formation of symbiotic associations with mycorrhizal fungi and stimulate the abundance of P\uffe2\uff80\uff90mineralizing and P\uffe2\uff80\uff90solubilizing micro\uffe2\uff80\uff90organisms. Releasing carboxylate exudates and phosphatases could accelerate SOC decomposition, whereas changing symbiotic associations and root morphological traits (e.g. an increase in fine root length) may contribute to higher SOC stabilization. Increased relative abundances of P\uffe2\uff80\uff90mineralizing and P\uffe2\uff80\uff90solubilizing bacteria can accelerate P mining and SOC decay, which may decrease microbial C use efficiency and subsequently lower SOC sequestration.
The trade\uffe2\uff80\uff90offs between different plant P\uffe2\uff80\uff90acquisition strategies under N loading should be among future research priorities due to their cascading impacts on soil C storage. Quantifying ecosystem thresholds for P adaption to increased N loading is important because P\uffe2\uff80\uff90acquisition strategies are effective when N loading is below the N threshold. Moreover, understanding the response of P\uffe2\uff80\uff90acquisition strategies at different levels of native soil N availability could provide insight to divergent P\uffe2\uff80\uff90acquisition strategies across sites and ecosystems. Altogether, P\uffe2\uff80\uff90acquisition strategies should be explicitly considered in Earth System Models to generate more realistic predictions of the effects of N loading on soil C cycling.
Read the free Plain Language Summary for this article on the Journal blog.
Increased human\uffe2\uff80\uff90derived nitrogen (N) loading in terrestrial ecosystems has caused widespread ecosystem\uffe2\uff80\uff90level phosphorus (P) limitation. In response, plants and soil micro\uffe2\uff80\uff90organisms adopt a series of P\uffe2\uff80\uff90acquisition strategies to offset N loading\uffe2\uff80\uff90induced P limitation. Many of these strategies impose costs on carbon (C) allocation by plants and soil micro\uffe2\uff80\uff90organisms; however, it remains unclear how P\uffe2\uff80\uff90acquisition strategies affect soil C cycling. Herein, we review the literature on the effects of N loading on P limitation and outline a conceptual overview of how plant and microbial P\uffe2\uff80\uff90acquisition strategies may affect soil organic carbon (SOC) stabilization and decomposition in terrestrial ecosystems.
Excessive input of N significantly enhances plant biomass production, soil acidification, and produces plant litterfall with high N/P ratios, which can aggravate ecosystem\uffe2\uff80\uff90level P limitation.
Long\uffe2\uff80\uff90term N loading can cause plants and soil micro\uffe2\uff80\uff90organisms to alter their functional traits to increase P acquisition. Plants can release carboxylate exudates and phosphatases, modify root morphological traits, facilitate the formation of symbiotic associations with mycorrhizal fungi and stimulate the abundance of P\uffe2\uff80\uff90mineralizing and P\uffe2\uff80\uff90solubilizing micro\uffe2\uff80\uff90organisms. Releasing carboxylate exudates and phosphatases could accelerate SOC decomposition, whereas changing symbiotic associations and root morphological traits (e.g. an increase in fine root length) may contribute to higher SOC stabilization. Increased relative abundances of P\uffe2\uff80\uff90mineralizing and P\uffe2\uff80\uff90solubilizing bacteria can accelerate P mining and SOC decay, which may decrease microbial C use efficiency and subsequently lower SOC sequestration.
The trade\uffe2\uff80\uff90offs between different plant P\uffe2\uff80\uff90acquisition strategies under N loading should be among future research priorities due to their cascading impacts on soil C storage. Quantifying ecosystem thresholds for P adaption to increased N loading is important because P\uffe2\uff80\uff90acquisition strategies are effective when N loading is below the N threshold. Moreover, understanding the response of P\uffe2\uff80\uff90acquisition strategies at different levels of native soil N availability could provide insight to divergent P\uffe2\uff80\uff90acquisition strategies across sites and ecosystems. Altogether, P\uffe2\uff80\uff90acquisition strategies should be explicitly considered in Earth System Models to generate more realistic predictions of the effects of N loading on soil C cycling.
Read the free Plain Language Summary for this article on the Journal blog.