Journal of Geophysical Research: Biogeosciences最新文献

{"title":"Bridging the Gap From Peat to Ponds: Terrestrial and Aquatic Greenhouse Gas Emissions in an Evolving Permafrost-Associated Subarctic Peatland","authors":"Melanie S. Burnett,&nbsp;Cynthia M. Kallenbach,&nbsp;Isabelle Laurion,&nbsp;Jérôme Comte,&nbsp;Roxane Maranger,&nbsp;Martial Leroy,&nbsp;Peter M. J. Douglas","doi":"10.1029/2025JG009509","DOIUrl":"https://doi.org/10.1029/2025JG009509","url":null,"abstract":"<p>Rapid permafrost thaw in peatlands transforms the subarctic landscape into a mosaic of ponds and peat soil, varying in moisture, carbon and nutrients, and time since thaw. As subarctic permafrost degrades, ponds emerge and mature and can gradually infill with <i>Sphagnum</i> peat. These ponds are considered hotspots of methane (CH₄) and carbon dioxide (CO₂) emissions, but their potential for nitrous oxide (N₂O) emissions is understudied. Moreover, how greenhouse gas (GHG) fluxes vary between these aquatic and terrestrial environments is unclear, largely because these ecosystems are typically studied separately. We quantified N₂O, CO₂, and CH₄ emissions along four transects from a degrading terrestrial palsa to ponds varying in age within a sporadic-permafrost subarctic peatland near Whapmagoostui-Kuujjuarapik, QC. We also characterized depth-dependent GHG concentrations in snow and peat. Waterlogged <i>Sphagnum</i> peat emitted, on average, 361% more C than drier bare peat above permafrost. GHG emissions from <i>Sphagnum</i> peat were comparable to pond emissions, with a greater proportion of CH₄, suggesting waterlogged systems represent key emission hotspots. Terrestrial N₂O fluxes were generally low, but the eroding palsa emitted more N₂O than saturated <i>Sphagnum</i> peat. In ponds, N₂O was consumed, indicating complete denitrification. Depth profiles of peat and snowpack GHG concentrations indicate likely emissions during winter. Terrestrial GHG fluxes, but not pond fluxes, were strongly associated with nitrogen availability. Our results suggest that future permafrost thaw, leading to bare peat degradation into ponds and the subsequent development of <i>Sphagnum</i> peat with presumably more N₂ fixation potential, will lead to sustained elevated C emissions from peatlands.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 4","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009509","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147666257","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":"Larsen C Ice Shelf in the Western Weddell Sea is a Hotspot for Export Production in the Antarctic Ocean","authors":"J. Mirkin,&nbsp;J. Granger,&nbsp;R. F. Flynn,&nbsp;A. G. West,&nbsp;S. Smith,&nbsp;M. N. Mathuri,&nbsp;K. E. Altieri,&nbsp;S. E. Fawcett","doi":"10.1029/2025JG009593","DOIUrl":"https://doi.org/10.1029/2025JG009593","url":null,"abstract":"<p>The Southern Ocean accounts for &gt;30% of the global ocean CO₂ sink as a result of its solubility and biological pumps. To investigate the biological pump near Larsen C Ice Shelf (LCIS) in the Southern Ocean's western Weddell Sea, we measured the concentrations and nitrogen isotope ratios of nitrate, ammonium, and particulate organic nitrogen sampled in mid-summer 2019. From the isotope data, we estimate a mean <i>f</i>-ratio (i.e., fraction of primary production available for export from the mixed layer, equivalent to the extent of phytoplankton reliance on subsurface nitrate) of 0.81 ± 0.18. This value is higher than parallel incubation-based <i>f-</i>ratio estimates (≤0.5), a divergence that we ascribe to the different integration timescales of the two methods (weeks for the isotope method and hours to days for the incubations) and to a tendency for increased phytoplankton reliance on regenerated nitrogen later in the growth season. The carbon export flux estimated from the seasonal decline in nitrate concentration was &gt;4.3 ± 1.7 mol C m⁻² year⁻¹, as much as nine times that estimated for the open Antarctic Zone. Our data reveal that the waters adjacent to LCIS contribute disproportionately to the Weddell Sea's biological pump, which we attribute mainly to the effect of ice-melt on stratification and iron supply. The CO₂ transferred by the biological pump into newly forming bottom waters will remain sequestered from the atmosphere for centuries.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 4","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009593","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147666306","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":"Effects of Meltwater on the Arctic Coastal Microbial Food Web: An Experiment With Isotopic Labeling From Young Sound, NE Greenland","authors":"IC Puts,&nbsp;A Mostovaya,&nbsp;HC Henson,&nbsp;L Allais,&nbsp;A de Kluijver,&nbsp;J Thyrring,&nbsp;M Middelboe,&nbsp;JM Holding","doi":"10.1029/2025JG008921","DOIUrl":"10.1029/2025JG008921","url":null,"abstract":"<p>The Arctic Ocean freshwater content is predicted to increase by 30%–50% during the 21st century, and especially coasts receive substantial amounts of freshwater from melting glaciers and thawing permafrost. The resulting increase in sediment and carbon inputs from rivers is changing seawater chemistry along Arctic coasts, potentially disrupting food web processes. Here, we test how sediment-rich river runoff carrying glacial meltwater affects the microbial food web in a Greenlandic fjord, by separating the effects of freshening alone from those combined with river- and land-derived compounds (river discharge). After enriching seawater with ¹³C-HCO₃⁻ and freshening it by 16% with either Milli-Q or river water, we monitored the response of natural microbial producers in both treatments. We tracked bacterial and algal biomass and production over 14 days and assessed fatty acids and their <i>δ</i>¹³C signatures. The results show that meltwater enriches the marine environment with silicon and nitrogen. Furthermore, a 16% dilution with river water stimulates bacterial —but not algal— production and biomass. The observed effects of meltwater are possibly due to impacts of labile organic carbon, inorganic (micro) nutrient inputs, or even the increased silicate concentration supporting biosilicifying bacteria. Still, the specific environmental factors supporting the increased bacterial activity remain speculative. Given the limited research on meltwater effects on microbial processes, we highlight key knowledge gaps and provide guidance for future experimental setups. Overall, we show that increased river discharge carrying meltwater enhances bacterial production, potentially impacting the entire ecosystem and emphasizing the significant influence of terrigenous freshwater inputs on coastal environments.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG008921","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147568032","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":"Diel Variation of CO2 Concentrations in Australian Irrigation Dams From Spring to Summer","authors":"Jackie R. Webb,&nbsp;Ellen Moon,&nbsp;Carlos Ballester,&nbsp;Rodrigo Filev Maia,&nbsp;Kerri Finlay","doi":"10.1029/2025JG009572","DOIUrl":"https://doi.org/10.1029/2025JG009572","url":null,"abstract":"<p>Small artificial waterbodies such as farm dams are recognized as important sources of anthropogenic emissions. Carbon dioxide (CO₂) fluxes from farm dams are highly variable across spatial scales, with sites acting as sources or sinks based on single daytime measurements. However, diel variations are an overlooked source of temporal variability in CO_2, complicating upscaling efforts. To provide a more accurate estimate of the CO₂ source-sink status of farm dams, four irrigation dams were monitored for dissolved CO₂ at half-hourly intervals over a five-month period in 2021–2022. Carbon dioxide concentrations were undersaturated between 12% and 37% of the measurements, indicating a dominance of CO₂ production over consumption when considering diel cycles and seasonal patterns. Carbon dioxide was consistently lower during daytime and early night periods compared with late-night and exhibited large diel shifts up to 57–99 μM. Diel CO₂ amplitude was driven primarily by metabolic controls, as revealed by strong correlations with dissolved oxygen and temperature, except for one irrigation dam which indicated CO₂ variation was driven by external inputs. Spatial variability based on previously acquired data (inter-dam coefficient of variation (CV) 105%) was higher than diel (CV 34%–54%) and seasonal (CV 13%–29%) variability. However, if only daytime CO₂ measurements are considered, total CO₂ emissions over the study period would be underestimated by between 11% and 148%, demonstrating the consequence of not including diel variation. Future refinements of upscaled farm dam CO₂ emission estimates will require more geographically dispersed studies that feature diel measurements to constrain uncertainty in these highly variable systems.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009572","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147568037","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":"Harnessing Stability-Guided Interpretable Machine Learning for Understanding and Predicting Water Quality in Freshwater Ecosystems","authors":"Rohit Shukla,&nbsp;Adrienne Breef-Pilz,&nbsp;Mary E. Lofton,&nbsp;Cayelan C. Carey,&nbsp;R. Quinn Thomas","doi":"10.1029/2025JG009545","DOIUrl":"10.1029/2025JG009545","url":null,"abstract":"<p>Harmful phytoplankton blooms driven by climate warming and nutrient pollution are a growing threat to freshwater ecosystems worldwide. Predicting these blooms is critical for managing water resources. However, process-based models often struggle to capture the complex nonlinear dynamics of phytoplankton. Although machine learning (ML) offers powerful predictive capabilities, its “black-box” nature has limited its adoption for management. In this study, we applied four ensemble ML algorithms, Extreme Gradient Boosting (XGBoost), Random Forest (RF), Gradient Boosting Machine (GBM), and Categorical Boosting (CatBoost), to model phytoplankton dynamics in two adjacent drinking-water reservoirs. All models performed similarly; however, the XGBoost algorithm achieved the best performance in both reservoirs, with a root mean square error (RMSE) of 2.4–6.6 μg/L chlorophyll a and a Pearson correlation coefficient (r) of 0.83–0.86. To enhance the interpretability of these ML models, we applied explainable artificial intelligence (XAI) techniques, including Shapley Additive Explanations (SHAP) and partial dependence analyses (PDPs). Our XAI analysis revealed reservoir-specific dynamics, with deep dissolved oxygen and water temperature more influential in one reservoir, whereas seasonality and water column stability were more critical in the other. We also observed opposing effects of thermal stratification, with high water temperatures and strong stratification stimulating phytoplankton in one reservoir and suppressing it in the other. Stability analyses confirmed that the SHAP explanations were robust to perturbations, boosting confidence in their interpretability. This study demonstrates the application of a stability-constrained XAI framework to provide transparent and trustworthy ecological insights, offering a robust approach for data-driven water quality management and forecasting.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009545","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147637173","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":"The Fate of Green Tide Organic Carbon in the Yellow Sea Revealed by Lipid Biomarkers","authors":"Hongsheng Wang,&nbsp;Miaomiao Zhao,&nbsp;Rong Bi,&nbsp;Huamao Yuan,&nbsp;Hailong Zhang,&nbsp;Jiwen Liu,&nbsp;Jiaxuan Cui,&nbsp;Shulan Xu,&nbsp;Yang Ding,&nbsp;Li Li,&nbsp;Meixun Zhao","doi":"10.1029/2025JG009384","DOIUrl":"https://doi.org/10.1029/2025JG009384","url":null,"abstract":"<p>Green tides, particularly the severe blooms of <i>Ulva prolifera</i> in the Yellow Sea since 2007, release significant amounts of organic carbon (OC); however, the fate of <i>U. prolifera</i>-derived OC is still unclear. This study traced <i>U. prolifera</i>-derived OC using its specific lipid biomarker (28-isofucosterol) in suspended particles and surface sediments across three regions of the Southern Yellow Sea (<i>U. prolifera</i> growth-impact, settlement, and non-outbreak regions) in May 2023. We also analyzed phytoplankton lipid biomarkers. Our findings revealed high concentrations of 28-isofucosterol (up to 141.91 ng L⁻¹) in the surface suspended particles within the non-outbreak region, associated with floating <i>U. prolifera</i> observed, indicating the impact of newly grown <i>U. prolifera</i> on OC. In the bottom suspended particles, 28-isofucosterol concentrations (62.74–83.65 ng L⁻¹) were comparable across all regions, indicating integrated signals of remnants from previous years. 28-isofucosterol thus remained detectable in suspended particles, showing its persistence and suitability as a tracer of <i>U. prolifera</i> deposition. Surface sediments, which reflect the inputs from multiple years, showed the highest contents of all lipid biomarkers in the settlement region. The proto-burial efficiency of <i>U. prolifera</i>-derived OC (2%–4%) was quantified for the first time and was considerably lower than that of total phytoplankton lipid biomarkers (a proxy for phytoplankton-derived OC) (13%–95%), emphasizing the transient nature of macroalgae-derived OC inputs compared to the sustained input from phytoplankton. Our findings underscore the need for integrated approaches to better understand the ecological impacts and carbon cycling dynamics as bloom condition escalate.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147568188","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":"The Fate of Green Tide Organic Carbon in the Yellow Sea Revealed by Lipid Biomarkers","authors":"Hongsheng Wang,&nbsp;Miaomiao Zhao,&nbsp;Rong Bi,&nbsp;Huamao Yuan,&nbsp;Hailong Zhang,&nbsp;Jiwen Liu,&nbsp;Jiaxuan Cui,&nbsp;Shulan Xu,&nbsp;Yang Ding,&nbsp;Li Li,&nbsp;Meixun Zhao","doi":"10.1029/2025JG009384","DOIUrl":"https://doi.org/10.1029/2025JG009384","url":null,"abstract":"<p>Green tides, particularly the severe blooms of <i>Ulva prolifera</i> in the Yellow Sea since 2007, release significant amounts of organic carbon (OC); however, the fate of <i>U. prolifera</i>-derived OC is still unclear. This study traced <i>U. prolifera</i>-derived OC using its specific lipid biomarker (28-isofucosterol) in suspended particles and surface sediments across three regions of the Southern Yellow Sea (<i>U. prolifera</i> growth-impact, settlement, and non-outbreak regions) in May 2023. We also analyzed phytoplankton lipid biomarkers. Our findings revealed high concentrations of 28-isofucosterol (up to 141.91 ng L⁻¹) in the surface suspended particles within the non-outbreak region, associated with floating <i>U. prolifera</i> observed, indicating the impact of newly grown <i>U. prolifera</i> on OC. In the bottom suspended particles, 28-isofucosterol concentrations (62.74–83.65 ng L⁻¹) were comparable across all regions, indicating integrated signals of remnants from previous years. 28-isofucosterol thus remained detectable in suspended particles, showing its persistence and suitability as a tracer of <i>U. prolifera</i> deposition. Surface sediments, which reflect the inputs from multiple years, showed the highest contents of all lipid biomarkers in the settlement region. The proto-burial efficiency of <i>U. prolifera</i>-derived OC (2%–4%) was quantified for the first time and was considerably lower than that of total phytoplankton lipid biomarkers (a proxy for phytoplankton-derived OC) (13%–95%), emphasizing the transient nature of macroalgae-derived OC inputs compared to the sustained input from phytoplankton. Our findings underscore the need for integrated approaches to better understand the ecological impacts and carbon cycling dynamics as bloom condition escalate.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147568077","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":"Organic Carbon Burial Rates in Muddy Temperate Shelf Sea Sediments","authors":"Hannah C. Muir,&nbsp;David G. Reading,&nbsp;Phillip E. Warwick,&nbsp;James A. Strong,&nbsp;Kate Peel,&nbsp;Rowan Henthorn,&nbsp;Jacqui Keenan,&nbsp;Peter F. Duncan,&nbsp;Jan G. Hiddink,&nbsp;Martin W. Skov,&nbsp;Richard K. F. Unsworth,&nbsp;Claire Evans","doi":"10.1029/2025JG009168","DOIUrl":"https://doi.org/10.1029/2025JG009168","url":null,"abstract":"<p>Muddy continental shelf sediments act as important sinks for atmospheric CO₂ by accumulating organic matter, a small fraction of which is buried and stored as organic carbon (OC) over long timescales. Quantifying long-term OC burial in shelf sediments is critical for understanding their role in climate regulation; however, this remains difficult due to limited age-resolved data and the challenges of determining sediment accumulation rates and temporal changes in OC content. To address this, we quantified age-resolved OC storage over the past two centuries in the upper 50 cm of the Western Irish Sea Mud Belt (WISMB) by measuring depth-resolved OC content and sediment accumulation rates. The OC content (0.15%–1.62%), OC storage (1.30–15.15 gC cm⁻³), and sediment accumulation rates (0.26–0.37 cm yr⁻¹) vary both spatially and temporally, with the highest OC accumulation and burial occurring in muddier, deeper-water sediments. Between 53% and 91% of the OC accumulated in the surface 2 cm over the past 8 years (17.09–39.47 gC m⁻² yr⁻¹), and 60%–68% of the OC accumulated in the upper 10 cm over the past 38 years (21.90–51.13 gC m⁻² yr⁻¹), remains buried for more than 100 years (14.03–33.50 gC m⁻² yr⁻¹). These rates are comparable to those reported for other muddy continental shelf regions, including mud patches, coastal fjords, and glacial troughs.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009168","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147666089","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":"Organic Carbon Burial Rates in Muddy Temperate Shelf Sea Sediments","authors":"Hannah C. Muir,&nbsp;David G. Reading,&nbsp;Phillip E. Warwick,&nbsp;James A. Strong,&nbsp;Kate Peel,&nbsp;Rowan Henthorn,&nbsp;Jacqui Keenan,&nbsp;Peter F. Duncan,&nbsp;Jan G. Hiddink,&nbsp;Martin W. Skov,&nbsp;Richard K. F. Unsworth,&nbsp;Claire Evans","doi":"10.1029/2025JG009168","DOIUrl":"https://doi.org/10.1029/2025JG009168","url":null,"abstract":"<p>Muddy continental shelf sediments act as important sinks for atmospheric CO₂ by accumulating organic matter, a small fraction of which is buried and stored as organic carbon (OC) over long timescales. Quantifying long-term OC burial in shelf sediments is critical for understanding their role in climate regulation; however, this remains difficult due to limited age-resolved data and the challenges of determining sediment accumulation rates and temporal changes in OC content. To address this, we quantified age-resolved OC storage over the past two centuries in the upper 50 cm of the Western Irish Sea Mud Belt (WISMB) by measuring depth-resolved OC content and sediment accumulation rates. The OC content (0.15%–1.62%), OC storage (1.30–15.15 gC cm⁻³), and sediment accumulation rates (0.26–0.37 cm yr⁻¹) vary both spatially and temporally, with the highest OC accumulation and burial occurring in muddier, deeper-water sediments. Between 53% and 91% of the OC accumulated in the surface 2 cm over the past 8 years (17.09–39.47 gC m⁻² yr⁻¹), and 60%–68% of the OC accumulated in the upper 10 cm over the past 38 years (21.90–51.13 gC m⁻² yr⁻¹), remains buried for more than 100 years (14.03–33.50 gC m⁻² yr⁻¹). These rates are comparable to those reported for other muddy continental shelf regions, including mud patches, coastal fjords, and glacial troughs.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009168","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147666088","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":"Nonlinear Elevation-Dependent Controls on Drought Responses of Vegetation Net Primary Production in the Central Himalayas","authors":"Jiujiang Wu,&nbsp;Yanqing Yang,&nbsp;Junli Zhao,&nbsp;Tao Ding,&nbsp;Wei Zhao","doi":"10.1029/2025JG009490","DOIUrl":"https://doi.org/10.1029/2025JG009490","url":null,"abstract":"<p>Climate warming is intensifying drought impacts on vegetation, especially in mountainous regions where complex topography mediates ecological responses. However, elevational variation in vegetation drought responses and their drivers remains unclear. Here, we assessed vegetation Net Primary Productivity (NPP) sensitivity to drought across elevations and vegetation types with multiple drought metrics in Nepal. Combining a structural equation model and random forest analyses, we quantified impact pathways and the relative importance of environmental drivers, providing new insights into drought impact. We found that drought frequency decreases with elevation in Nepal. Both the probability and intensity of drought-induced NPP loss showed nonlinear elevation patterns, decreasing before increasing, with inflection points around 3,200–3,600 m and 4,000–4,400 m, respectively. Although severe NPP loss was generally associated with stronger droughts, the convergence of loss thresholds at higher elevations reflects reduced ecological resilience and heightened vulnerability of alpine systems. Temperature emerged as the dominant driver of loss intensity and represented the most upstream climatic control in the pathway (mean <i>β</i> = 0.37), while vegetation condition and soil moisture, respectively, dominated the indirect regulation of loss probability and intensity. However, the drivers of NPP loss reorganize along the elevation gradient, with single factor dominance at low elevations, a temperature importance peak at ∼3,000 m, and co-regulation by multiple factors at high elevations. This study advances our understanding of nonlinear climatic stress in mountain ecosystems.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147566680","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}