Journal of Geophysical Research: Biogeosciences最新文献

{"title":"Characteristics of Stemflow Nitrate and Its Isotopic Composition in a Temperate Pine Plantation","authors":"Yanhong Cao,&nbsp;Xinchao Sun,&nbsp;Liangxia Su,&nbsp;Chunyu Wang,&nbsp;Mengyao Wang,&nbsp;Baolu Yang","doi":"10.1029/2024JG008560","DOIUrl":"https://doi.org/10.1029/2024JG008560","url":null,"abstract":"<p>Increasing atmospheric nitrate (NO₃⁻) deposition can influence plant growth and productivity and has been studied in forest biogeochemical cycles. However, the transport and fate of atmospheric NO₃⁻ via stemflow (SF) remain poorly understood. We investigated the concentrations and fluxes of SF NO₃⁻ in relation to the influencing factors at both the inter- and intra-event scales, and used the δ¹⁵N, δ¹⁸O, and Δ¹⁷O values to elucidate the transformations and sources of SF NO₃⁻ in a temperate Chinese pine plantation throughout two growing-season periods. SF NO₃⁻ concentrations decreased exponentially, whereas SF NO₃⁻ fluxes linearly increased with increasing inter-event bulk precipitation (BP) volume. Using a linear mixed model, it was determined that SF NO₃⁻ fluxes of individual trees were significantly influenced by tree height, rainfall duration, and rainfall intensity. The intra-event SF NO₃⁻ concentrations exponentially decreased to a steady input, and this trend was significantly influenced by rainfall volume. Furthermore, both the δ¹⁵N and δ¹⁸O values of SF NO₃⁻ were significantly enriched compared to those of BP, indicating that tree trunks played an important role in buffering dry deposition. Based on a mass-balance approach using the Δ¹⁷O values, it was found that SF NO₃⁻ was derived almost entirely from atmospheric deposition, while biological nitrification was rarely detected but occurred in October. This may be related to microbial nitrifying activity on tree trunks. These findings enhance the mechanistic understanding of the translocation and transformation of SF NO₃⁻ and provide insights for determining the loss of nitrogen from soil via leaching and denitrification.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143904927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impacts of Plant Functional Group Dominance and Geochemical Factors on Soil Carbon Concentrations and Fractions in Grassland Ecosystems","authors":"Pengfei Chang,&nbsp;Nairsag Jalaid,&nbsp;Meifeng Deng,&nbsp;Junsheng Huang,&nbsp;Zhou Jia,&nbsp;Lu Yang,&nbsp;Zhenhua Wang,&nbsp;Sen Yang,&nbsp;Yuntao Wu,&nbsp;Shengnan Pan,&nbsp;Lingli Liu","doi":"10.1029/2024JG008530","DOIUrl":"https://doi.org/10.1029/2024JG008530","url":null,"abstract":"<p>Climate change and anthropogenic activities are reshaping plant functional group dominance and altering soil physicochemical properties in grassland ecosystems. Although plant carbon inputs, microbial activity, and mineral protection are known to govern soil carbon turnover, how changes in functional group dominance and geochemical factors regulate carbon storage and stability remains unclear. Here, we selected 124 mono-species patches of 12 common grass, forb, and woody species in a temperate grassland nature reserve, measuring plant chemical traits, microbial biomass carbon (MBC), and soil physicochemical properties. We found that across all plant functional groups, root, and microbial contributions outweighed aboveground inputs in soil organic carbon (SOC) formation. Soil mineral properties, especially exchangeable calcium, played predominant roles in influencing soil carbon concentration, surpassing the impact of plant and microbial input. Despite sandier soil and lower plant carbon input in woody patches, bulk soil carbon concentration, and its mineral-associated organic carbon and particulate organic carbon fractions in woody patches did not differ from those in grass and forb patches. Further analysis revealed that woody patches had higher soil moisture, which increased MBC and fostered organo-mineral interactions. These processes could facilitate SOC stabilization, thereby compensating for low root carbon input and the low carbon retention capacity of sandy soils. Overall, our findings reveal how biotic and geochemical factors interact to regulate SOC and its fractions across plant functional groups, highlighting the crucial role of exchangeable calcium and soil moisture in driving organic carbon concentrations in temperate grasslands.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidence for the Coupling of Plant Functional Diversity and Soil Biogeochemistry Under Climatic Stress in Pacific Northwest Grasslands","authors":"Barbara Bomfim,&nbsp;Hilary R. Dawson,&nbsp;Paul B. Reed,&nbsp;Katherine L. Shek,&nbsp;Brendan J. M. Bohannan,&nbsp;Scott D. Bridgham,&nbsp;Lucas C. R. Silva","doi":"10.1029/2024JG008126","DOIUrl":"https://doi.org/10.1029/2024JG008126","url":null,"abstract":"<p>Increasing warming and drought severity are projected for the Pacific Northwest (PNW) and are expected to negatively impact species composition and ecosystem function. In this study, we test the hypothesis that the impact of climatic stress (i.e., experimental warming and drought) on PNW grasslands are mediated by interactions between plant functional diversity and soil biogeochemical processes, including symbiotic nitrogen (N) fixation in legumes and free-living asymbiotic nitrogen fixation (ANF) by soil microorganisms. To test this hypothesis, we measured the response of plants and soils to three years of warming (+2.5°C) and drought (−40% precipitation) in field experiments replicated at three different sites across a ∼520-km latitudinal gradient. We observed interactive effects of warming and drought on functional diversity and soil biogeochemical properties, including both positive and negative changes in ANF. Although direct measurements of symbiotic nitrogen fixation (SNF) rates were not conducted, the observed variations in ANF, in conjunction with changes in legume cover, suggest a compensatory mechanism that may offset reductions in SNF. Generally, high ANF rates coincided with low legume cover, suggesting a connection between shifts in species composition and N cycling. Our ANF estimates were performed using isotopically labeled dinitrogen (¹⁵N₂) in tandem with soil carbon (C), phosphorus (P) and iron (Fe), pH, and moisture content. Along the latitudinal drought severity gradient, ANF rates were correlated with changes in species composition and soil N, P, moisture, and pH levels. These results highlight the importance of soil-plant-atmosphere interactions in understanding the impacts of climatic stress on ecosystem composition and function.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Longer Ice-Free Conditions and Increased Run-Off From the Ice Sheet Will Impact Primary Production in Young Sound, Greenland","authors":"Marie Maar,&nbsp;Janus Larsen,&nbsp;Vibe Schourup-Kristensen,&nbsp;Eva Friis Møller,&nbsp;Mie Hylstofte Sichlau Winding,&nbsp;Lorenz Meire,&nbsp;Mikael Sejr","doi":"10.1029/2024JG008468","DOIUrl":"https://doi.org/10.1029/2024JG008468","url":null,"abstract":"<p>The Arctic coastal ocean is among the habitats most impacted by climate change due to the cumulative impact of several interacting drivers. The high-Arctic Young Sound in north-east Greenland is characterized by a short ice-free period (July–October). The system is influenced by high run-off, mainly from glacial meltwater during summer (June–September) affecting the turbidity. Our analysis showed that Young Sound has experienced a longer period without sea ice since 1950 due to global warming and increased run-off due to melting of the land-terminating glaciers. We applied a 3D ecosystem model for Young Sound to estimate present-day primary production and potential future change (25 and 50 years) in different scenarios of future sea ice-free periods and run-off. The light model was improved by including suspended particulate matter (SPM) released with the freshwater sources. A shorter period with sea ice coverage gave an increase of annual primary production due to a longer productive season in the model. Increased glacial run-off was found to decrease annual primary production due to more light attenuation from SPM. However, a spatial displacement of primary production was observed in the water column and between areas due to changes in light and nutrient availability. When longer ice-free periods and higher run-off were combined, primary production showed a modest increase overall except for areas with a deep productive layer suffering from stronger light limitation. The present study can contribute to a better understanding and generalization of future productivity of Greenland fjords.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008468","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143888960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decoupling of the Organic and Inorganic Lacustrine Carbon Cycles on the Chinese Yunnan Plateau in Response to Human Activities","authors":"Aubrey L. Hillman,&nbsp;Daniel J. Bain,&nbsp;Duo Wu,&nbsp;Mark B. Abbott","doi":"10.1029/2024JG008336","DOIUrl":"https://doi.org/10.1029/2024JG008336","url":null,"abstract":"<p>As anthropogenic impacts to both climate and freshwater resources continue to intensify in coming decades, an increasing number of lakes will experience carbon cycle perturbations. An examination of lakes that have experienced such perturbations for millennia can clarify the nature and severity of carbon cycle disturbances. Lakes precipitating carbonate minerals provide an opportunity to use measurements of both inorganic and organic carbon isotopes to detect the relationship between the inorganic and organic carbon cycles. We examine these dynamics among three lakes in Yunnan, China, which have been impacted by human activities for the last 1,500 years. We compare the period impacted by people to drying conditions and lowering lake levels during the middle Holocene, and more stable hydrologic conditions during the later Holocene, both of which are characterized by minimal anthropogenic influence. From 5,500 to 3,500 years BP, decreased precipitation, increased evaporation, and changes in vegetation drove increases in sediment carbon isotope values. Despite continued weakening of the Indian monsoon from 3,500 to 1,500 years BP, carbon isotopes values stabilized. Following anthropogenic manipulation of lake levels after 1,500 years BP, and despite differences in the magnitude of activities in the three catchments, a decrease in inorganic carbon isotopes without a parallel change in organic carbon isotopes is a pervasive feature in each system and a clear signature of human activity. We suggest possible drivers are an influx of dissolved inorganic carbon from either oxidized organic matter or dissolved carbonates from the watershed and/or the respiration of lake sediment organic matter.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeled Seed Accumulation Patterns Explain Spatial Heterogeneity of Shrub Recruitment Within the Taiga-Tundra Ecotone","authors":"Cory A. Wallace,&nbsp;Evan J. Wilcox,&nbsp;Trevor C. Lantz,&nbsp;Philip Marsh,&nbsp;Jennifer L. Baltzer","doi":"10.1029/2024JG008359","DOIUrl":"https://doi.org/10.1029/2024JG008359","url":null,"abstract":"<p>Arctic shrub productivity trends display variability at multiple spatial scales. Fine-scale studies have generally observed the greatest shrub expansion in landscape positions that accumulate water and nutrients. While considerable work has focused on the mediating effect of these resources on growth responses to warming, less is known about the mechanisms constraining recruitment-driven expansion. Given the low seed viability of many Arctic shrubs, spatial patterns of seed dispersal may play an important role in constraining fine-scale variability of shrub recruitment. This variability may also be driven by ground cover suitability, though these relationships are understudied in undisturbed sites. Here, we developed models representing seed accumulation mechanisms around <i>Alnus alnobetula</i> (green alder) patches within the taiga-tundra ecotone of the Northwest Territories and compared these with observations of seed and seedling density. We also investigated relationships between seedling abundance, topographic position, and ground cover. Observed patterns of recruitment were complex, with preferential expansion occurring beneath alder patches only on the steepest slopes. Seed accumulation models representing overland flow, wind, and source distance were important predictors of seedling recruitment. This provides indirect evidence of localized seed limitation around patches, suggesting future recruitment may not respond as expected to changing environmental conditions. <i>Sphagnum</i> cover also predicted recruitment, indicating the importance of seedbed conditions for establishment. We propose that developing models of shrub expansion that include both dispersal and environmental constraints may increase our ability to predict patterns and rates of expansion. Such predictions are necessary to understand future biosphere-atmosphere interactions in a rapidly changing Arctic.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008359","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143861910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advancing Estuarine Science and Management Through Long-Term Research and Monitoring in the U.S. National Estuarine Research Reserve System","authors":"Kaitlin L. Reinl,&nbsp;Robert P. Dunn,&nbsp;Christopher Kinkade,&nbsp;Kimberly Cressman","doi":"10.1029/2024JG008630","DOIUrl":"https://doi.org/10.1029/2024JG008630","url":null,"abstract":"<p>Long-term research and monitoring programs are critical to our understanding of ecosystem processes. Although short-term studies are one effective method for scientific investigations, they cannot elucidate the role of medium to long-term cycles and lag effects in ecosystem processes, limiting our ability to interpret trends and interactions among processes. Because funding for environmental sciences is inherently limited, and work that addresses current societal needs is often prioritized over basic research and monitoring efforts, the design of long-term studies needs to be creative and intentional. This will allow it to address relevant and pressing issues to remain competitive for funding while also being useful for conducting basic and applied research across a broad range of topics. We use prior studies from the U.S. National Estuarine Research Reserve System's System-Wide Monitoring Program to illustrate the value of long-term studies and demonstrate how they can be designed to directly address management needs, advance our fundamental ecological understanding of aquatic ecosystems, and better serve our communities.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008630","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143861792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Redox Properties of Peat Particulate Organic Matter From Five Ombrotrophic Bogs in Central Sweden","authors":"Nikola Obradović,&nbsp;Rob A. Schmitz,&nbsp;Silvan Arn,&nbsp;Myrna Simpson,&nbsp;Nivetha Srikanthan,&nbsp;Ronald Soong,&nbsp;Martin H. Schroth,&nbsp;Michael Sander","doi":"10.1029/2024JG008337","DOIUrl":"https://doi.org/10.1029/2024JG008337","url":null,"abstract":"<p>Peat particulate organic matter (POM) is increasingly recognized as an important terminal electron acceptor (TEA) for anaerobic microbial respiration in anoxic peat soils. The goal of this work was to quantify the electron-accepting capacity (EAC) of POM that is accessible to microbes in these soils under in situ conditions. To this end, we collected 28 reduced POM samples from the anoxic subsurface along transects in <i>Sphagnum</i>-dominated ombrotrophic bogs in central Sweden. These POM samples had similar physicochemical properties and compositions within and across peatlands, as inferred from elemental analysis, infrared spectroscopy, and solid-state ¹³C nuclear magnetic resonance spectroscopy. The microbially accessible EAC of these POM samples were determined by quantifying the increases in the total EACs and concomitant decreases in electron-donating capacities when reacting the field-collected reduced POM with dissolved oxygen (DO). These analyses suggested that between 90 and 390 μmol electrons per gram of POM carbon are microbially transferrable to POM. The reaction of POM with DO was found to also result in equimolar conversion of electron-donating to electron-accepting moieties in POM, demonstrating fully reversible electron transfer to and from POM and, therefore, that POM is a sustainable TEA in temporarily anoxic peat soils. A comparison of the microbially accessible EAC of POM to that of pore-water inorganic TEA species and reported EACs and measured concentrations of peat-dissolved organic matter revealed that POM is the major TEA in the studied bogs.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal Variation in δ13Cn-alkane and δ13C/ δ15N of Bulk Leaves of Four Riparian Plants: Implications for Biomarker Carbon Isotope Records of Past Environments","authors":"Michael T. Hren,&nbsp;Abigail M. Oakes,&nbsp;Alex Brittingham","doi":"10.1029/2024JG008496","DOIUrl":"https://doi.org/10.1029/2024JG008496","url":null,"abstract":"<p>Carbon isotopes of long chain <i>n</i>-alkanes and plant leaves record biochemical processes and plant responses to environmental factors. We analyzed seasonal variations of δ¹³C_{<i>n</i>-alkane} and δ¹³C/δ¹⁵N_leaf of two riparian gymnosperm trees (<i>Pinus strobus</i> and <i>Tsuga canadensis</i>) and an angiosperm shrub and grass (<i>Corylus americana</i> and <i>Phalaris arundinacea</i>) to quantify carbon isotope discrimination between atmospheric, bulk leaf, and <i>n</i>-alkane δ¹³C. Our data highlight three important results: (a) δ¹³C leaf and δ¹³C_{<i>n</i>-alkane} decrease over the growing season for several of the sampled plants and the magnitude of change is largest in the angiosperm <i>C. americana</i>, (b) apparent fractionation between δ¹³C_<i>n</i>-C29 and δ¹³C_leaf (ε_{<i>n</i>-C29-leaf}) for gymnosperm trees is small (−2 to −3 ‰) and changes little through the growing season, and (c) angiosperm grass and shrubs exhibit variable discrimination (ε) throughout the growing season (−4 to −10‰). ε_{<i>n</i>-C29-leaf} correlates with leaf C:N and δ¹⁵N_leaf, and differences in ε_{<i>n</i>-C29-leaf} likely result from differences in stomatal regulation, plant stoichiometry, and the distribution of compounds in leaves and above or below ground biomass. In some of the plants sampled, end of growing season δ¹³C of intact leaves are distinct from early or mid-season values, whereas detrital <i>n</i>-alkane δ¹³C records the season-long time-integrated history of production, loss and replacement of riparian-produced <i>n</i>-alkanes. Thus, although biomarker and bulk leaf δ¹³C may record <i>p</i>CO₂ or water stress, isotopic signatures of sedimentary <i>n</i>-alkanes may also reflect changes in plant resource allocation and the integrated record of isotopic change across a growing season.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nutrient Limitation Induces a Productivity Decline From Light-Controlled Maximum","authors":"Yuseung Shin,&nbsp;Alexander J. Reisinger,&nbsp;Madison Flint,&nbsp;Tatiana Salinas,&nbsp;Jonathan B. Martin,&nbsp;Matthew J. Cohen","doi":"10.1029/2024JG008597","DOIUrl":"https://doi.org/10.1029/2024JG008597","url":null,"abstract":"<p>Nutrient impacts on productivity in stream ecosystems can be obscured by light limitation imposed by canopy cover and water turbidity, thereby creating uncertainties in linking nutrient and productivity regimes. Evaluations of nutrient limitations are often based on a response ratio (RR) quantifying productivity stimulation above ambient levels given augmented nutrient supply. This metric neglects the primacy of light effects on productivity. We propose an alternative approach to quantify nutrient limitations using a “decline ratio” (DR), which quantifies the productivity decline from the maximum established by light availability. The DR treats light as the first-order control and nutrient depletion as a disturbance causing productivity decline, allowing separation of nutrient and light influences. We used DR to assess nutrient diffusing substrate (NDS) experiments with three nutrients (nitrogen [N], phosphorus [P], iron [Fe]) from five Greenland streams during summer, where light is not limited due to the lack of canopy and low turbidity. We tested two hypotheses: (a) productivity maximum (i.e., highest chlorophyll-<i>a</i> among NDS treatments) is controlled by light and (b) DR depends on both light and nutrients. The productivity maximum was strongly predicted by light (<i>R</i>² = 0.60). The productivity decline induced by N limitation (i.e., DR_N) was best explained by light availability when parameterized with either dissolved inorganic nitrogen concentration (<i>R</i>² = 0.79) or N:Fe ratio (<i>R</i>² = 0.87). These predictions outperformed predictions of RR for which light was not a significant factor. Reversing the perspective on nutrient limitation from “stimulation above ambient” to “decline below maximum” provides insights into both light and nutrient impacts on stream productivity.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008597","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143840691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}