Journal of Geophysical Research: Biogeosciences最新文献

{"title":"Modification and Comparison of Two Urban Vegetation Models Over Southern Ontario, Canada","authors":"Sabrina Madsen-Colford, Lucy Hutyra, Ian Smith, Dien Wu, M. Altaf Arain, Ralf Staebler, William Ma, Natalia Restrepo-Coupe, Debra Wunch","doi":"10.1029/2025JG008943","DOIUrl":"10.1029/2025JG008943","url":null,"abstract":"<p>Despite significant emissions of anthropogenic carbon dioxide (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <msub>\u0000 <mtext>CO</mtext>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${text{CO}}_{2}$</annotation>\u0000 </semantics></math>) in cities, fluxes of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <msub>\u0000 <mtext>CO</mtext>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${text{CO}}_{2}$</annotation>\u0000 </semantics></math> to and from urban ecosystems can significantly impact local carbon budgets. In this work, we use the city of Toronto, Canada, as a testbed to compare two urban vegetation models: the Solar-induced chlorophyll fluorescence for Modeling Urban biogenic Fluxes (SMUrF) model and the Urban Vegetation Photosynthesis and Respiration Model (UrbanVPRM). We make several adjustments to both models to improve their agreement with three eddy-covariance flux towers in the region surrounding the city, enhance the spatial resolution, and better represent biogenic fluxes in urban areas. Compared to flux tower observations, the net ecosystem exchange estimates improved substantially during the spring and autumn for the updated UrbanVPRM and during spring and summer for the updated SMUrF model. These adjustments also result in significantly better agreement between the two models in Toronto during 2018–2021. While discrepancies remain between the updated models, likely due to the use of different driving variables, they are substantially smaller than differences between anthropogenic <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <msub>\u0000 <mtext>CO</mtext>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${text{CO}}_{2}$</annotation>\u0000 </semantics></math> emissions estimated by two commonly used emission inventories. We find that during summer afternoons both the UrbanVPRM and SMUrF models predict <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <msub>\u0000 <mtext>CO</mtext>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${text{CO}}_{2}$</annotation>\u0000 </semantics></math> uptake of between half and all of Toronto's mean anthropogenic summer afternoon emissions, dependi","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG008943","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144910161","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":"Quantifying Soil Erosion-Induced Lateral Carbon Loss in the East China Coast","authors":"Liya Zhu,&nbsp;Zhongli Liu,&nbsp;Yan Li,&nbsp;Ke Hu","doi":"10.1029/2024JG008727","DOIUrl":"10.1029/2024JG008727","url":null,"abstract":"<p>Soil erosion profoundly impacts the lateral transport of soil organic carbon (SOC) from land to ocean. However, previous research has mainly focused on specific sites characterized by SOC loss through field measurements, leaving a gap in constructing the long-term estimates of lateral redistribution of SOC. In this study, we establish a centennial soil erosion and lateral SOC transport (CEST) framework to explore the magnitude and spatial heterogeneity of SOC loss in the East China Coast (ECC). By utilizing machine-learning approaches and the Revised Universal Soil Loss Equation model in conjunction with measured and satellite-derived data and CMIP6 data, the CEST framework allows for investigating SOC erosion distribution from 1980 to 2100. The results show that during the baseline period (1980–2020), the average potential SOC erosion rate in the surface soil (0–20 cm) was 0.122 t C ha⁻¹ yr⁻¹, which was higher than the overall average in China, and led to an annual redistribution of 13.85 Tg C of SOC. During the future period, by the year 2100, the SOC erosion will decrease by 1.61 Tg yr⁻¹ under the SSP119 scenario, while it will increase by 6.74 Tg yr⁻¹ under the SSP585 scenario. The total SOC erosion is mainly located in areas with an altitude of 300–1500 m, a slope range of 10°–15°, and low vegetation cover (NDVI &lt; 0.6). Besides, vegetation plays a central role in slowing down SOC erosion, offsetting the contribution from precipitation increase.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 8","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144897408","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":"Estimating Sea Ice Algal Biomass in Svalbard Fjords Using Underwater Hyperspectral Imaging: Integrating Laboratory and Field Calibration Approaches","authors":"Janina Osanen,&nbsp;Karley Campbell,&nbsp;Zoé Forgereau,&nbsp;Laura M. Garcìa,&nbsp;Ilka Peeken,&nbsp;Mats A. Granskog,&nbsp;Rolf Gradinger,&nbsp;Benjamin A. Lange","doi":"10.1029/2025JG008784","DOIUrl":"10.1029/2025JG008784","url":null,"abstract":"<p>Sea-ice algae are an integral part of the polar marine ecosystems, but they remain under-sampled due to the limitations of invasive sampling techniques, the large spatial heterogeneity of their biomass and logistical challenges conducting research in remote regions. This study provides an assessment of an underwater hyperspectral imager (UHI) on a simple L-arm as a tool to better monitor sea ice algal community biomass based on data sets from in situ sampling of two Svalbard fjords as well as laboratory cultures of ice algae. We use normalized difference indexes (NDIs) to quantify chlorophyll <i>a</i> (chl <i>a</i>) from UHI surveys, using both standardized radiance and transmittance for comparison. Our results demonstrate that while both approaches work in a laboratory setting, the transmittance-based NDIs capture the in situ patchiness of chl <i>a</i> more effectively, revealing differences of up to 4 mg/m² at fine scales (2 cm) that are unachievable with traditional sampling methods. We developed a new approach for NDI calibration, where a mixed species sample from natural sea ice was cultivated to determine an optimal NDI which then was applied to in situ UHI-surveys, reducing the need for extensive invasive ice coring. We also show the importance of calibrating NDIs to case-specific algal species, since even a minor shift in composition can reduce NDI effectiveness by nearly 50%. This study adds to the potential of using UHIs paired with NDIs for small-scale characterization and quantification of sea-ice algal chl <i>a</i>, while showcasing a new and simpler approach for calibration of bio-optical models.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 8","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG008784","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144888266","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":"Contrasting Effects of Road Dust and Atmospheric Dust on Carbon Accumulation in Eastern Canadian Ombrotrophic Peatlands","authors":"Xiaoyu Li,&nbsp;Julie Talbot,&nbsp;James King","doi":"10.1029/2024JG008502","DOIUrl":"10.1029/2024JG008502","url":null,"abstract":"<p>Limited research has been conducted on the role of atmospheric dust as a nutrient source for peatlands, and none has studied the effects of localized and intense road dust on peatland carbon (C) accumulation. To compare the effects of dust deposition from these two sources on peatlands, we examined three ombrotrophic peatlands adjacent to unpaved (gravel) roads in eastern Canada. We find that road dust deposition increases the ash content of peat and decreases its stoichiometric ratios of C, nitrogen (N), and phosphorus (P), with the greatest changes occurring at the site receiving the highest road dust deposition. The dust record since 5,500 cal BP, reconstructed using ICP-MS analysis of lithogenic elements in a peat core, reveals seven dust episodes. The most recent episode, predominantly from road dust, exhibits a flux 19–95 times higher than the background atmospheric dust flux depending on the reference element. In the catotelm layer of the peat core, the atmospheric dust flux exhibits significant positive correlations with C, N, P, and potassium (K) accumulation rates alongside negative correlations with the C:N and C:P ratios. In contrast, the C accumulation rate is lowest closest to the road and increases with distance away from the road as a result of changes in vegetation composition, nutrient availability, and water levels. The different effects of atmospheric dust and road dust suggest that there may be a threshold effect of dust or nutrient inputs, especially P, on peatland C accumulation.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 8","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008502","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144869318","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":"Field-Based Estimation of Carbon Stocks of Bamboo Forests Across China","authors":"Ming Ouyang,&nbsp;Wenjing Fang,&nbsp;Anwar Eziz,&nbsp;Shuli Xiao,&nbsp;Suhui Ma,&nbsp;Zhengbing Yan,&nbsp;Chengjun Ji,&nbsp;Jiangling Zhu,&nbsp;Jinming Hu,&nbsp;Qingpei Yang,&nbsp;Zhiyao Tang,&nbsp;Jingyun Fang","doi":"10.1029/2025JG009238","DOIUrl":"10.1029/2025JG009238","url":null,"abstract":"<p>Bamboo forests substantially contribute to the biogeochemical cycling of carbon (C) and help mitigate climate change. Moso bamboo (<i>Phyllostachys edulis</i>), which occupies the largest bamboo forest area globally, is widely distributed across China. However, the C stocks of these forests and their controlling factors remain poorly quantified due to a lack of large-scale field data. Here, we conducted a nationwide survey of 322 plots and 1,245 soil samples throughout the full distribution range of moso bamboo forests in China. We estimated a total ecosystem C stock of 511.0 ± 9.9 Tg C, with 29% stored in vegetation and 71% in soil (0–50 cm). Vegetation C density was weakly influenced by climate but increased under moderate human disturbance. Soil C density was shaped by both climate and human activity: higher temperature, precipitation, and wetness index promoted soil C accumulation, whereas intensive disturbance indirectly reduced soil C by decreasing soil moisture and nitrogen content. These findings suggest that increasing drought and intensified human activity may reduce soil C sequestration in bamboo ecosystems. Our study provides a new field-based estimate of C stocks in China's bamboo forests and offers insights to improve biogeochemical models and inform C sink management.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 8","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144869403","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 Typhoon on Phytoplankton and CDOM in the South China Sea Revealed by BGC-Argo Floats and Satellite Composite Analysis","authors":"Yupeng Shao,&nbsp;Han Zhang,&nbsp;Yeping Yuan,&nbsp;Yuntao Wang,&nbsp;Wei Fan,&nbsp;Xiaogang Xing","doi":"10.1029/2025JG008966","DOIUrl":"10.1029/2025JG008966","url":null,"abstract":"<p>The impacts of typhoons on phytoplankton have been studied for decades, but most studies have relied on satellite-derived sea-surface chlorophyll (Chl), which is now recognized as an inadequate proxy of phytoplankton biomass. Moreover, typhoon effects on colored dissolved organic matter (CDOM) remain poorly understood. Using Biogeochemical Argo (BGC-Argo) float observations from two typhoon cases and 20-year satellite measurements from 235 typhoons (2003–2022), we analyzed phytoplankton and CDOM responses to typhoons in the South China Sea. Our results demonstrated the vertical redistribution process, driven by mixing entrainment or typhoon-induced upwelling, rapidly elevated surface Chl and CDOM by transporting subsurface high-concentration waters upward. Phytoplankton growth lagged 3–5 days due to light limitation until clear skies returned, and surface biomass increased by only ∼14.5%, lower than the surface Chl increase (∼20%). The variance of sea-surface Chl was dominated by vertical redistribution and photoacclimation, largely decoupled from biomass. These results underscore that studies relying on surface Chl substantially mischaracterized the response dynamics of phytoplankton. Moreover, CDOM exhibited a secondary peak following the typhoon passage, coinciding with maximum biomass response, indicating newly produced CDOM from the phytoplankton bloom. Future work should focus on quantifying the contributions of various processes and refining response periods by incorporating additional BGC-Argo data and improving synergy between in situ observation and marine biogeochemical models.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 8","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144853770","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 Key Role of Xylem Hydraulic Vulnerability in Influencing Interannual Growth Variability of Earlywood and Latewood Across the Northern Hemisphere","authors":"Mengyun Sun,&nbsp;Lixin Wang,&nbsp;Steven A. Kannenberg,&nbsp;Hongyan Liu,&nbsp;Christopher R. Schwalm,&nbsp;Philippe Ciais,&nbsp;Pierre Gentine,&nbsp;William Kolby Smith,&nbsp;Kailiang Yu,&nbsp;Wen Zhang,&nbsp;Yang Li,&nbsp;Yuting Yang,&nbsp;Ximeng Li,&nbsp;Zhenju Chen,&nbsp;Deliang Chen,&nbsp;Peng Zhang,&nbsp;Xiuchen Wu","doi":"10.1029/2025JG008837","DOIUrl":"10.1029/2025JG008837","url":null,"abstract":"<p>Estimating interannual variability of earlywood and latewood growth is crucial for assessing the fluctuations in forest carbon sequestration. However, with amplified climate variations, it remains unclear how earlywood and latewood growth vary across space and over time, as well as the key driving factors that influence these patterns. Here, we quantified the interannual variability of earlywood (EW_CV) and latewood (LW_CV) from 1901 to 2013 based on 596 tree-ring chronologies across the Northern Hemisphere and investigated their spatial-temporal patterns. Using Boosted Regression Tree models, we assessed which factors related to climate, hydraulic status, plant structure, and stand properties determine EW_CV and LW_CV. We found that both EW_CV and LW_CV were higher in drier regions, but they exhibited divergent spatial distribution patterns. This may be because earlywood is more affected by local long-term aridity, whereas latewood appears to be more prone to within-season water availability. Besides, xylem hydraulic vulnerability (P₅₀, xylem water potential at 50% loss of hydraulic conductance) emerged as the key influencing factor of growth fluctuation in both earlywood and latewood. These findings suggest that differences in hydraulic functions between earlywood and latewood play a key role in how trees adapt to water stress. Our results illuminate the mechanisms of how earlywood and latewood respond to changing climatic conditions and highlight the crucial role of hydraulic functions in vegetation model prediction of tree growth.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 8","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144853768","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":"Riverine Influence on Coastal Biogeochemistry Along a 400-km Latitudinal Gradient in Eastern James Bay","authors":"Michaela de Melo,&nbsp;Caroline Fink-Mercier,&nbsp;Virginie Galindo,&nbsp;Michel Gosselin,&nbsp;Urs Neumeier,&nbsp;Huixiang Xie,&nbsp;Paul A. del Giorgio","doi":"10.1029/2025JG008793","DOIUrl":"10.1029/2025JG008793","url":null,"abstract":"<p>Rivers integrate climate signals, landscape gradients, and environmental disturbances at the watershed scale, strongly influencing downstream ecosystems and ultimately coastal waters. Watershed environmental gradients therefore exert a strong local influence on coastal river plumes, yet it is unclear how regional-scale gradients involving multiple watersheds are coupled to broad patterns of coastal marine biogeochemistry and productivity. Here, we aimed to establish connections between the physicochemical properties of rivers draining into the highly riverine-influenced James Bay (JB) and of the properties of coastal waters along its entire eastern shore. We clustered 17 river outlets and over 140 coastal sites along a 400-km latitudinal gradient of the eastern JB, sampled during two consecutive summers, according to trends in nutrients, suspended particulate matter, colored dissolved organic matter, freshwater discharge, and salinity. Our findings reveal notable latitudinal changes in the physicochemical properties of both rivers and coastal waters along JB, which were spatially coherent. Whereas river discharge exerts a significant influence—higher discharge amplifies the riverine impact on coastal waters—this alone does not account for the observed variability along the coast. The riverine influence differs among areas and depends on variables considered. In this study, we identified biogeochemical transition zones and assessed the impact of river exports on coastal waters along JB, and this integrative approach could be applied to disentangle river-coast interactions in other regions.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 8","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG008793","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144853769","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":"Reversal of the Litter N Effect on Decomposition at Higher N Addition Rates","authors":"Aijun Xing,&nbsp;Haihua Shen,&nbsp;Mengying Zhao,&nbsp;Jingyun Fang","doi":"10.1029/2024JG008570","DOIUrl":"10.1029/2024JG008570","url":null,"abstract":"<p>Nitrogen (N) in the litter and soil inorganic N can have contrasting effects on litter decomposition, such that the positive effects of litter N on the rate of decomposition will likely decrease with increased soil inorganic N due to possible suppression of lignin oxidase. To test this, we reciprocally buried litter collected from multiple treatments in an N addition experiment (0, 20, 50, and 100 kg N ha⁻¹ yr⁻¹). With increasing N addition, we found that the concentration of N in the litter and the availability of inorganic N in the soil increased linearly. Contrary to our expectations, the litter N effects on decomposition changed nonlinearly with the N addition, first decreasing with the N addition rates but then reversed at the highest N addition treatment. This reversal at higher N rates is mainly due to a change in soil decomposing microbes with N addition. We examined the activity of extracellular enzymes in soil and found that phenol oxidase activity was not affected by N addition, but cellulase activity increased linearly with N addition rates. We further found that the relative abundance of bacterial functional genes involved in cellulose and the abundance of soft-rot fungi that decay cellulose increased with N addition. Our study contrasts the assumption that increased soil inorganic N suppresses lignin oxidation and instead reveals an increase in cellulolytic groups and activity of cellulase; this shift in decomposing microbes mediates the litter N effects on decomposition and suggests that more slowly decomposing fractions might be less affected.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 8","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144833135","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":"Above and Belowground Carbon Dynamics of a Degraded Mountain Peatland","authors":"Charuni Jayasekara,&nbsp;Catherine Leigh,&nbsp;Jeff Shimeta,&nbsp;Ewen Silvester,&nbsp;Samantha Grover","doi":"10.1029/2025JG008822","DOIUrl":"10.1029/2025JG008822","url":null,"abstract":"<p>Peatlands are typically net CO₂ sinks and CH₄ sources under intact or undisturbed conditions due to near-surface water tables, which create anoxic conditions that limit aerobic decomposition and promote methanogenesis. However, disturbances can disrupt this balance by altering hydrology and vegetation. In Australian mountain <i>Sphagnum</i> peatlands, vegetation change is often used to assess biophysical condition, but the effects of degradation on carbon dynamics remain poorly understood. Therefore, this study aimed to investigate the above- and below-ground carbon dynamics of a degrading Australian mountain <i>Sphagnum</i> peatland. We used the manual chamber method to measure CO₂ and CH₄ fluxes from moss-present and moss-absent areas of the peatland, over six measurement occasions in the growing season, across 2 years. A 14-month in situ mesh bag incubation experiment was also conducted to assess the decomposition rates of two peat substrates (fresh and degraded) at three different depths (5, 15, and 30 cm). The results indicated that both moss-present and moss-absent areas of the peatland acted as net CO₂ sources due to lowered water table levels than intact peatlands, moss-vegetation loss, and altered peat structure. Both areas had reduced CH₄ emissions due to the low water table and the absence of aerenchyma plants in the peatland. Organic matter decomposition rates of the peatland are mainly affected by the water table level and secondarily by substrate quality and peat depth. This study concluded that the carbon balance of degrading mountain peatlands is mainly controlled by the water table level, vegetation composition, and the quality of the substrate being decomposed.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 8","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG008822","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144833134","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}