Journal of Geophysical Research: Biogeosciences最新文献

{"title":"Patterns in Stream pCO2 and CO2 Emissions in a Subtropical Steep Headwater System, Southeastern China","authors":"Yuchao Wang,&nbsp;Weifeng Wang,&nbsp;Boran Liu,&nbsp;Honghua Ruan,&nbsp;Xuan Xu,&nbsp;Changshan Jin,&nbsp;Chenyang Li,&nbsp;Feng Li","doi":"10.1029/2024JG008683","DOIUrl":"https://doi.org/10.1029/2024JG008683","url":null,"abstract":"<p>The evasion of CO₂ from streams is recognized as a significant component of the global carbon cycle. However, both the magnitude and the underlying mechanisms of stream CO₂ flux remain uncertain. In this study, stream partial pressure of carbon dioxide (<i>p</i>CO₂) and CO₂ flux were estimated in a steep subtropical headwater system in Wuyishan National Park, southeastern China, from November 2021 to July 2022. The results showed that <i>p</i>CO₂ ranged from 317 to 1,808 μatm, and CO₂ flux from 24 to 4,717 mmol m⁻² d⁻¹. Significant seasonal variation was observed for both variables: <i>p</i>CO₂ was higher in the dry season, whereas CO₂ flux was significantly higher in the wet season, reflecting contrasting biogeochemical and hydrodynamic controls. Spatially, CO₂ flux varied across slope gradients and stream orders, whereas <i>p</i>CO₂ showed no clear spatial trend. The Mixed-Effects Models performed well for both <i>p</i>CO₂ (<i>R</i>² = 0.5788, <i>p</i> &lt; 0.001) and CO₂ flux (<i>R</i>² = 0.5116, <i>p</i> &lt; 0.001). Soil CO₂ concentration, oxidation-reduction potential (ORP) and pH were the dominant predictors of <i>p</i>CO₂, indicating strong terrestrial carbon inputs and chemical regulation, while CO₂ flux was governed primarily by gas transfer velocity and its associated hydrodynamic drivers including slope, alongside water chemical indicators dissolved oxygen and ORP. Overall, this study reveals the magnitude, seasonal and spatial variations, and influencing factors of <i>p</i>CO₂ and CO₂ flux in subtropical steep mountain streams. These findings highlight the substantial CO₂ emission potential of the subtropical steep headwater systems studied here.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467608","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":"Tibetan Pasture Restoration Causes Additional Cooling by Reflecting Solar Radiation","authors":"Zhuangzhuang Wang,&nbsp;Zhaoheng Deng,&nbsp;Da Wei,&nbsp;Yaqiong Lu,&nbsp;Xiaodan Wang","doi":"10.1029/2025JG009479","DOIUrl":"https://doi.org/10.1029/2025JG009479","url":null,"abstract":"<p>The Tibetan Plateau is home to Earth's largest alpine pastures, where livestock populations have more than doubled over the past half century, contributing widespread pasture degradation. In response, large-scale restoration has been implemented (9% of pastures have been restored) despite a tripling in human population and food demand. The biogeochemical impacts of alpine pasture restoration, such as enhanced CO₂ uptake, are well documented, whereas its biophysical consequences remain poorly understood. Here, we show that restoration is associated with substantial litter accumulation, increased surface albedo, and consequent changes in the surface energy balance. Surveys of 11 paired restored pasture sites revealed 20%–45% increases in litter accumulation, consistent across alpine steppe, meadow, and wetland. Long-term paired observations in representative alpine steppe and wetland ecosystems further showed that litter retained in the absence of herbivory increasingly covered the dwarf canopy and was associated with increases in surface albedo of 0.02–0.04 and a 7% reduction in net radiation. Sensitivity experiments suggest that increased albedo alters surface energy partitioning, reducing sensible heat flux by 0.15 W m⁻² and increasing latent heat flux by 0.01 W m⁻² over the Tibetan Plateau, with stronger responses within restoration areas. These lines of evidence highlight a previously underappreciated biophysical pathway, whereby restoration-induced litter accumulation enhances surface reflectivity and alters land-atmosphere energy exchange, contributing to a more comprehensive understanding of the climatic impacts of pasture restoration.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467607","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":"Microbially Mediated Transformation of Labile Iron in Estuarine Surface Sediments: Implications for Benthic Trace Element Cycling","authors":"Baorong Huang,&nbsp;Zhe Zhou,&nbsp;Ni Su,&nbsp;Jiangtao Li,&nbsp;Shouye Yang,&nbsp;Yalei Zhang","doi":"10.1029/2026JG009747","DOIUrl":"https://doi.org/10.1029/2026JG009747","url":null,"abstract":"<p>Estuarine sediments are critical zones for element cycling between land and ocean, where redox oscillation driven by unsteady sedimentation amplifies the role of iron (Fe) as a reversible regulator for the benthic cycling of trace elements. Yet, key uncertainties persist regarding the quantitative partitioning and the mineralogical mechanisms of microbially mediated Fe(III) reduction, especially the distribution of newly formed Fe(II) between solid phase and porewater. Here, surficial sediments from the Changjiang Estuary were incubated with the Fe-reducing bacterium Ferrimonas balearica, with or without additional molybdate amendment and subjected to reoxygenation experiments. Based on sequential extractions and Flow-Through Time-Resolved Analyses (FT-TRA), we found that microbial Fe(III) reduction promoted the formation of authigenic Fe(II) minerals, potentially Fe carbonate, which preceded the release of Fe²⁺ into porewater. Inhibition of sulfate reduction significantly facilitated Fe(II) accumulation in the solid phase and reduced the release of Fe²⁺ and P, suggesting a crucial role of sulfide-mediated chemical reduction of Fe(III) in Fe²⁺ and P liberation. Multiple trace metals (e.g., Cr, Co) exhibited strong correlations with Fe²⁺ release (<i>p</i> &lt; 0.01), and FT-TRA revealed the enhanced lability of these trace elements in solid phase after microbial incubation. During reoxidation, Fe²⁺ was rapidly oxidized and precipitated. Subsequently, dissolved P was retained by newly formed Fe(III) oxyhydroxides, highlighting the reversible nature of labile Fe and its high efficiency in elemental mobilization during redox oscillation. These results provide quantitative evidence of microbially mediated labile Fe transformation processes in dynamic estuarine environments.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467335","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":"Revising the Magnitude and Trends of the Global Methane Soil Sink With Process-Based, Machine-Learning, and Atmospheric Inversion Modeling Approaches","authors":"Youmi Oh,&nbsp;Licheng Liu,&nbsp;Jaehyun Lee,&nbsp;Lori Bruhwiler,&nbsp;Xin Lan,&nbsp;Sylvia Michel,&nbsp;Sourish Basu,&nbsp;John B. Miller,&nbsp;Qing Zhu,&nbsp;Sparkle Malone,&nbsp;Gavin McNicol,&nbsp;Qianlai Zhuang","doi":"10.1029/2025JG009668","DOIUrl":"https://doi.org/10.1029/2025JG009668","url":null,"abstract":"<p>Methane (CH₄) oxidation by microbes is the largest biological sink of global methane, yet its magnitude and long-term variability remain uncertain. Here, we combined process-based (PB), machine-learning (ML), and atmospheric inversion approaches to evaluate the global methane soil sinks and its implication for the atmospheric CH₄ budget in this study. Both PB and ML approaches estimated annual global methane soil sink to be 40–45 Tg CH₄ yr⁻¹, 30%–50% larger than conventional estimates. Although the two approaches agreed on total magnitude, they differ in their representation of variability. PB models simulate stronger spatial heterogeneity, seasonality, and long-term increases in CH₄ uptake because environmental sensitivities are explicitly represented through mechanistic equations. In contrast, ML models reproduce site-level observations more closely but exhibit muted spatial and temporal variability due to their limited environmental sensitivities from sparse and discrete observations used for model training. Atmospheric inversions further indicate that incorporating the larger soil sink improves agreement with observed atmospheric CH₄ and its stable carbon isotope changes and requires larger microbial CH₄ emissions. Together, these results suggest that the global methane soil sink may have been underestimated and demonstrate the value of integrating PB and ML modeling, and atmospheric constraints to improve understanding of global methane cycling.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009668","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467379","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":"Historical Records of Nutrient Loading Into End-Member Mid-Latitude Lakes","authors":"M. A. Brannon,&nbsp;C. A. Scholz,&nbsp;M. L. Chipman,&nbsp;C. T. Driscoll","doi":"10.1029/2026JG009679","DOIUrl":"https://doi.org/10.1029/2026JG009679","url":null,"abstract":"<p>Human-induced environmental changes impact lakes in temperate regions, but detailed lake basin histories that pre-date instrumental records are limited. Most paleolimnological reconstructions are used to examine single lakes in isolation, making it difficult to separate regional forcings from morphological influences on a sedimentary signal. Here we compare sediment cores from Skaneateles and Oneida lakes (New York, USA), lakes with similar climate histories but different limnological characteristics. We reconstruct two centuries of nutrient loading, organic matter sourcing, and carbonate dynamics, to test how basin character influences the record of cultural eutrophication. Using ²¹⁰Pb-dated cores and paired analyses of total phosphorus (P), total organic carbon (TOC), total nitrogen (TN), δ¹³C, and CaCO₃, we identify a mid-twentieth-century signal in which mass accumulation, CaCO₃, P, and δ¹³C shift synchronously, contemporaneous with post-war land-use intensification and documented regional warming. Across all four cores, declining C/N and progressively lighter δ¹³C record a long-term shift toward autochthonous, algal-derived organic matter, with the clearest productivity records preserved at the deeper, less-disturbed sites. Sediment P remained elevated or continued to increase after the implementation of late-twentieth-century controls on external P loading. Strong coupling to iron indicates a redox-sensitive legacy reservoir of P capable of sustaining internal loading even where external inputs have been controlled. These results suggest that cultural eutrophication is recorded in both lakes, while inter-lake differences are governed largely by morphology. Interpreting sedimentary nutrient archives and managing freshwater systems under continued climate change requires accounting for both basin character and legacy nutrient reservoirs.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JG009679","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467376","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":"Methane and Nitrous Oxide Reshape the Air-Water Greenhouse Gas Budget of a Tropical Estuarine Delta","authors":"Luiz C. Cotovicz Jr.,&nbsp;Renato P. Ribeiro,&nbsp;Luciana O. Vidal,&nbsp;Marcelo C. Bernardes,&nbsp;Carlos E. De Rezende,&nbsp;Batiaan A. Knoppers,&nbsp;Gwenaël Abril","doi":"10.1029/2026JG009956","DOIUrl":"https://doi.org/10.1029/2026JG009956","url":null,"abstract":"<p>Estuaries are important sources and sinks of greenhouse gases (GHGs), yet assessments of their radiative balance often focus primarily on carbon dioxide (CO₂), with less attention given to methane (CH₄) and nitrous oxide (N₂O). We combine measurements of CH₄ and N₂O air-water fluxes with concurrent CO₂ data in a tropical estuarine delta (Paraíba do Sul River, Brazil), based on three surveys under contrasting hydrological conditions. CH₄ concentrations were highest in freshwater-dominated waters and mangrove creeks and decreased seaward, with greater values during high river discharge. Surface waters were supersaturated in CH₄, indicating a permanent atmospheric source driven by freshwater inputs and organic matter degradation. In contrast, N₂O exhibited weaker variability and alternated between source and sink, with concentrations linked to ammonium (NH₄⁺) and apparent oxygen utilization, suggesting nitrification as a dominant control. In CO₂-equivalent terms, CH₄ emissions offset 30%–84% of the CO₂ sink during dry conditions and enhanced CO₂ emissions by 20%–44% during high discharge. N₂O exerted a smaller but variable influence, either reinforcing or partially counterbalancing CO₂ fluxes. Together, CH₄ and N₂O offset 10%–85% of the CO₂ sink in dry periods and added 18%–42% to CO₂ emissions during wet conditions. The relative influence of CH₄ and N₂O was greatest where CO₂ fluxes were near equilibrium, particularly in the mixing and marine domains. Because many tropical deltas exhibit mixing-driven CO₂ uptake of weak magnitude, CH₄ and N₂O fluxes can reshape the radiative balance, underscoring the need for combined GHG assessments where CO₂ exchange is low or bidirectional.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JG009956","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467087","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":"Riparian Processing of Upland Groundwaters Strongly Influences Downstream Transport and Channel Emission of Dissolved Inorganic Carbon Along Agricultural Stream Corridors","authors":"Qipei Shangguan,&nbsp;Robert A. Payn,&nbsp;Madison J. Foster,&nbsp;Caitlin M. Mayernik,&nbsp;Stephanie A. Ewing,&nbsp;Michael D. DeGrandpre","doi":"10.1029/2025JG009370","DOIUrl":"https://doi.org/10.1029/2025JG009370","url":null,"abstract":"&lt;p&gt;Headwater streams gain groundwater carrying dissolved inorganic carbon (DIC) from terrestrial environments and are hotspots for biogeochemical processing. The Judith River Watershed is located in a semi-arid region of the northern Great Plains in central Montana, where stream corridors have spatial variation in hydrological connectivity among upland landscapes, riparian aquifers and stream channels, allowing for assessment of the role of riparian zone in corridor DIC processing. Upland groundwaters draining into stream corridors either contribute directly to the stream channel as surface flow (i.e., springs) or recharge biogeochemically active subsurface flow paths through riparian substrates. Here, we quantified DIC lateral inputs via springs versus riparian groundwater, carbon dioxide (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) emissions from channel waters, and estimated stream metabolism based on continuous two-station monitoring of dissolved oxygen (DO) and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; at three corridor reaches across different seasons and years. We found that the three stream reaches received different proportions of riparian groundwater and springs. Reaches dominated by riparian groundwater inflows had &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and DIC concentrations that were typically two times greater compared to the reach dominated by spring inflows, and displayed larger seasonal variations in discharge (15–100 L &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;s&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; gas transfer velocities (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;k&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;C&lt;/m","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009370","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467088","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":"Divergent Thermal Habitat Responses to Climate Forcing in Shallow and Deep Lakes: The Role of Solar Radiation","authors":"Ryuichiro Shinohara,&nbsp;Shin-ichiro S. Matsuzaki,&nbsp;Maki Shinozaki,&nbsp;Mirai Watanabe,&nbsp;Megumi Nakagawa,&nbsp;Takayuki Satou","doi":"10.1029/2026JG010054","DOIUrl":"https://doi.org/10.1029/2026JG010054","url":null,"abstract":"<p>Climate warming is expected to reduce thermal habitat for cold-water fishes, yet the magnitude and direction of habitat change may depend on interactions among multiple climatic drivers. We analyzed two contrasting lakes in the same region—Lake Kasumigaura (a shallow, eutrophic lake) and Lake Inawashiro (a deep, oligotrophic lake)—to clarify whether increases in air temperature or solar radiation drive thermal habitat loss or expansion of pond smelt (<i>Hypomesus nipponensis</i>) over the last 30 years. One-dimensional numerical simulations revealed that their thermal habitat changes proceeded in opposite directions in the two lakes. In Lake Kasumigaura, recent increases in air temperature warmed the water column to levels exceeding historical observations. Summer water temperatures frequently exceeded the critical thermal maximum of pond smelt (CT_max = 29.1°C), resulting in a loss of optimal thermal habitat (15.0 &lt; <i>T</i>_opt &lt; 29.1°C). In contrast, in Lake Inawashiro, exceedance of CT_max was rare, and the duration and vertical extent of the optimal thermal habitat increased. This downward expansion of the thermal habitat was driven by increased surface solar radiation during the springtime. These results demonstrate that combined effects of warming and increased solar radiation do not uniformly reduce thermal habitat for cold-water fishes; instead, biological responses can diverge depending on interactions among multiple climatic drivers and intrinsic lake properties. These contrasting patterns highlight the importance of lake morphology and water clarity in shaping the thermal habitat of cold-water fish under continued climate change.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JG010054","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467041","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":"Influence of Prolonged Submergence or Exposure to Air on Photosynthesis and Carbon Dioxide Exchange in a Microtidal Spartina Alterniflora Salt Marsh","authors":"Abby M. Lesniewski,&nbsp;Charles A. Schutte,&nbsp;Ryann Rossi,&nbsp;Scott F. Jones,&nbsp;Brian J. Roberts","doi":"10.1029/2026JG009735","DOIUrl":"https://doi.org/10.1029/2026JG009735","url":null,"abstract":"<p>Salt marshes are widespread along temperate coastlines globally. They provide myriad ecosystem services that support natural and human systems. Some salt marsh plants, like <i>Spartina alterniflora</i>, grow best in a window of elevation within the tidal range that results in a regular pattern of inundation and exposure that the plant is adapted to. However, in microtidal environments, regional wind patterns can supersede tides and alter patterns of inundation and exposure, sometimes resulting in large areas of marsh that are inundated or exposed for a week or more at a time. Here, we report on a mesocosm-based experiment to determine the influence of these longer-term inundation/exposure events on plant metabolism and carbon dioxide (CO₂) exchange. We show that longer periods of exposure (&gt;5 days) increased plant photosynthetic capacity but did not alter respiration, while longer periods of inundation did not alter CO₂ exchange. Since prolonged periods of inundation and exposure typical of microtidal environments can result in changes in carbon exchange with the atmosphere, it is important to account for these differences when calculating annual salt marsh carbon budgets in microtidal environments. If a microtidal salt marsh experiencing wind forcing spends significantly more time inundated or exposed than it would because of tidal cycles alone, then a carbon budget not accounting for periods of prolonged inundation and exposure may inaccurately calculate the annual carbon exchange of that marsh.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JG009735","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466989","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":"Assessing the Relative Roles of Soil Water Potential and Atmospheric Demand on Vegetation Water Stress in Semi-arid Ecosystems","authors":"Kayla Jamerson,&nbsp;Zachary H. Hoylman,&nbsp;Anna Sala,&nbsp;Ashley Ballantyne,&nbsp;Colin Brust,&nbsp;Kelsey G. Jencso","doi":"10.1029/2025JG009009","DOIUrl":"https://doi.org/10.1029/2025JG009009","url":null,"abstract":"<p>Understanding vegetation's response to soil water availability and atmospheric demand is critical for assessing the impact of drought and climate change on semi-arid ecosystems. However, limited field-based research has been conducted to assess the relative importance of these drivers on vegetation productivity. Furthermore, previous research often simplifies the assessment of soil water availability by relying on soil volumetric water content (VWC) as the primary control on plant growth. Unlike soil water potential (Ψ_soil), VWC does not account for the effects of soil texture on plant water uptake. To address these gaps, we compared remotely sensed indicators of vegetation response with field-based measurements of VWC, relative humidity, and temperature (used to calculate vapor pressure deficit (VPD)) and soil temperature from 52 rangeland sites in Montana. Soil samples were collected at each site to generate a continuous time series of soil water potentials. We utilized generalized additive models to assess the relationship between our biophysical metrics and satellite-derived estimates of vegetation productivity, including the Enhanced Vegetation Index, near-infrared reflectance vegetation index (NIRv), and solar-induced fluorescence. Results suggest that Ψ_soil is a better biophysical predictor of seasonal vegetation productivity, while VPD emerges as a secondary driver in the absence of Ψ_soil limitations. Finally, anomalies in Ψ_soil were the dominant driver of anomalies in seasonal vegetation response. These findings indicate that soil water potential is a primary control on vegetation water stress across semi-arid landscapes.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 7","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466960","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}