Journal of Geophysical Research: Biogeosciences最新文献_第8页

Role of Micrometeorological Memory in Modulating Sub-Daily Scale Variability of Net Ecosystem Exchange

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2025-01-22 DOI: 10.1029/2024JG008356

Akash Verma, Leena Khadke, Elizabeth Eldhose, Subimal Ghosh

{"title":"Role of Micrometeorological Memory in Modulating Sub-Daily Scale Variability of Net Ecosystem Exchange","authors":"Akash Verma, Leena Khadke, Elizabeth Eldhose, Subimal Ghosh","doi":"10.1029/2024JG008356","DOIUrl":"https://doi.org/10.1029/2024JG008356","url":null,"abstract":"Net Ecosystem Exchange (NEE) is crucial for understanding the carbon balance in ecosystems, indicating whether they act as carbon sinks or sources. While the impact of hydrometeorological factors on NEE at daily and monthly scales has been well-researched, the significance of sub-daily variability and the influence of memory in micrometeorological variables remain understudied. This study addresses this gap by analyzing the temporal dynamics of NEE using half-hourly data from 29 FLUXNET sites over at least 6 years. We found that sub-daily variability of NEE contributes 10%–55% of 13-day NEE variability, depending on seasonal cycles and biome characteristics. Using an information theory based transfer entropy (TE) approach, we identified the causal drivers of NEE variability at sub-daily scales within a 6-hr memory. Our results show that the memory of micrometeorological variables significantly impacts NEE, surpassing their instantaneous effects. Temperature (TA), vapor pressure deficit (VPD), and soil water content (SWCMean) consistently affect NEE within this 6-hr memory, whereas the influence of sensible heat (H) and incoming shortwave radiation (SWIN) diminishes at higher lags. While the magnitude of average TE from micrometeorological variables to NEE exhibits notable seasonal variations, the temporal structure of how information is transferred does not significantly differ across seasons, as reflected by the shape of TE values over various time lags. SWCMean, VPD, and TA impact NEE jointly, while H and SWIN have overlapping effects. Additionally, precipitation influences NEE indirectly through SWCMean. Our findings highlight the importance of accounting for high-frequency NEE variability and its underlying drivers when investigating the ecohydrological interactions, shedding light on the role of memory in carbon-water interactions.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143118171","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}

引用次数: 0

Assessing Simulations of Forest Hurricane Disturbance and Recovery in Puerto Rico by ELM-FATES Using Field Measurements

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2025-01-21 DOI: 10.1029/2024JG008350

Mingjie Shi, Michael Keller, Barbara Bomfim, Lara Kueppers, Charlie Koven, Jessica Needham, Tamara Heartsill-Scalley, L. Ruby Leung

{"title":"Assessing Simulations of Forest Hurricane Disturbance and Recovery in Puerto Rico by ELM-FATES Using Field Measurements","authors":"Mingjie Shi, Michael Keller, Barbara Bomfim, Lara Kueppers, Charlie Koven, Jessica Needham, Tamara Heartsill-Scalley, L. Ruby Leung","doi":"10.1029/2024JG008350","DOIUrl":"https://doi.org/10.1029/2024JG008350","url":null,"abstract":"In the past three decades, Puerto Rico (PR) experienced five hurricanes that met or exceeded category three, and they caused severe forest structural damage and elevated tree mortality. To improve our mechanistic understanding of hurricane impacts on tropical forests and assess hurricane-affected forest dynamics in Earth system models, we use in situ forest measurements at the Bisley Experimental Watersheds in Northeast PR to evaluate the Functionally Assembled Terrestrial Ecosystem Simulator coupled with the Energy Exascale Earth System Model Land Model (ELM-FATES). The observations show that before Hurricane Hugo, 77.3% of the aboveground biomass (AGB) is from the shade-tolerant plant function type (PFT). The Hugo-induced mortality rates are over ∼50%, and they induce a ∼39% AGB reduction, which recovers to a level like the pre-Hugo condition in 2014, following a second, lower intensity hurricane, Georges. We perform numerical experiments that simulate damage from Hugo and Georges on the forests, including defoliation, sapwood and structural biomass damage, and hurricane-induced mortality. ELM-FATES can reasonably represent coexistence between the two PFTs–light-demanding and shade-tolerant–for both the pre-Hugo and post-Hugo conditions. The model represents a reasonable size distribution of mid-and large-sized trees although it underestimates AGB, likely due to the overestimated nonhurricane mortality. ELM-FATES temporarily stimulated leaf biomass and diameter increment after Georges, an effect that should be tested with observations of future hurricane defoliation events. This research indicates that addressing model-data mismatches in tree mortality and understory dynamics are essential to simulation of more extreme hurricane effects under climate change.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008350","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143117799","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}

引用次数: 0

Biogeochemistry of Riverine Organic Matter Inputs to the Patagonian Fjords and Implications for Fjord Organic Carbon Budgets

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2025-01-20 DOI: 10.1029/2024JG008531

Sebastien Bertrand

{"title":"Biogeochemistry of Riverine Organic Matter Inputs to the Patagonian Fjords and Implications for Fjord Organic Carbon Budgets","authors":"Sebastien Bertrand","doi":"10.1029/2024JG008531","DOIUrl":"https://doi.org/10.1029/2024JG008531","url":null,"abstract":"Fjords are increasingly recognized as hotspots for organic carbon (OC) burial. The OC buried in fjords is of both marine and terrestrial origin, with a predominance of terrestrial OC in fjords worldwide. The proportions of marine and terrestrial OC in fjords are traditionally calculated using end-member modeling based on δ13C and/or N/C. However, characterizing the terrestrial end-member remains a challenge, with authors inconsistently using measurements obtained on land plants, soils, and/or river sediments. Here, we analyzed the TOC, δ13C, and N/C composition of soil samples, suspended river sediments, and bulk and grain-size fractions of river sediments from the main rivers discharging into the Patagonian fjords (44–48°S), to identify the processes that affect the biogeochemistry of the terrestrial organic matter reaching fjords via rivers. Radiocarbon measurements indicate that Patagonian rivers contain 0.18% petrogenic OC and variable concentrations of biospheric OC. Despite soil δ13C significantly decreasing with precipitation, δ13C in river sediments remains relatively stable around −27‰. In contrast, N/C in river sediments is highly variable, mostly due to a high contribution of petrogenic nitrogen in glacier-fed rivers. Furthermore, N/C varies significantly with sediment grain size, making it virtually impossible to define a fixed N/C value to represent the terrestrial end-member. By comparison, grain size has a limited influence on δ13C. Overall, our results support the use of riverine δ13C to define terrestrial OC in mixing models, regardless of the presence of glaciers in the watershed, and they suggest that the fraction of terrestrial OC buried in fjord sediments may have been underestimated.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008531","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143117234","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}

引用次数: 0

Atmospheric Dryness Constrains CO2 Uptake During the Peak Growing Season and at Noontime in an Alpine Wetland Ecosystem

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2025-01-14 DOI: 10.1029/2024JG008262

Liqin Hua, Jing Tao, Yahui Qi, Zhuangzhuang Wang, Da Wei, Xiaodan Wang

{"title":"Atmospheric Dryness Constrains CO2 Uptake During the Peak Growing Season and at Noontime in an Alpine Wetland Ecosystem","authors":"Liqin Hua, Jing Tao, Yahui Qi, Zhuangzhuang Wang, Da Wei, Xiaodan Wang","doi":"10.1029/2024JG008262","DOIUrl":"https://doi.org/10.1029/2024JG008262","url":null,"abstract":"Increase in atmospheric dryness, characterized as vapor pressure deficit (VPD), might constrain terrestrial productivity. Nevertheless, the precise temporal impacts of VPD on the gross primary productivity (GPP) of alpine wetland ecosystems during the growing season remain elusive. The alpine ecosystems of the Tibetan Plateau (TP), where productivity is highly constrained by the cold climate, have experienced pronounced warming of 0.26°C decade−1 with associated increase in VPD. In this study, by examining eddy covariance observations taken in an alpine wetland on the TP over five consecutive years, we characterized when and how VPD variation causes negative impact on ecosystem productivity. The TP alpine wetland functioned as a net CO2 sink with magnitude of 164.6 ± 22.0 g C m−2 yr−1. It was found that VPD played a crucial role in the seasonal variation in GPP especially in the peak growing season, that is, it even suppressed the positive effect of temperature on GPP. As temperatures declined in the latter stages of the growing season, the inhibitory effect of VPD on GPP gradually diminished. We further found that the VPD at midday (13:00–14:30) was crucial for inhibition of photosynthesis and midday depression of GPP. Our results emphasize the role of atmospheric dryness during the middle growing season and at midday on GPP, thereby providing new insights into how VPD affects CO2 uptake in a warming climate.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143115107","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}

引用次数: 0

Multiple Elevation-Dependent Climate Signals From Quantitative Wood Anatomical Measurements of Rocky Mountain Bristlecone Pine

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2025-01-14 DOI: 10.1029/2024JG008307

Julie Edwards, Will L. Tintor, Alexandre F. Nolin, Connie A. Woodhouse, Georg von Arx, Kevin J. Anchukaitis

{"title":"Multiple Elevation-Dependent Climate Signals From Quantitative Wood Anatomical Measurements of Rocky Mountain Bristlecone Pine","authors":"Julie Edwards, Will L. Tintor, Alexandre F. Nolin, Connie A. Woodhouse, Georg von Arx, Kevin J. Anchukaitis","doi":"10.1029/2024JG008307","DOIUrl":"https://doi.org/10.1029/2024JG008307","url":null,"abstract":"Southwestern North America has experienced significant temperature increases over the last century, leading to intensified droughts that significantly affect montane forests. Although tree-ring data have provided long-term context for this recent drought severity, the varying physiological responses of trees to climate variability make it challenging to disentangle the combined influence of temperature and soil moisture. Here we investigate complex climate-growth relationships in Rocky Mountain bristlecone pine (Pinus aristata) at a low-elevation and a high-elevation site using quantitative wood anatomy (QWA). Significant correlations with climate were found for low-elevation tree-ring width (TRW) and earlywood chronologies, including positive correlations with spring and early summer precipitation and drought indices and negative correlations with spring and early summer maximum temperatures. At high elevations, TRW and earlywood chronologies show positive responses to summer moisture, whereas latewood chronologies correlate positively with August and September maximum temperatures and negatively with August precipitation. We leverage this differing seasonality of moisture and temperature signals and compare the QWA data to known droughts. The earlywood lumen area is found to be highly responsive to drought because of its physiological reliance on water availability for maintaining turgor pressure during cell enlargement. We also observed a decline in temperature sensitivity at the high elevation site, suggesting shifts in the dominance of limiting factors. Integrating QWA with traditional dendrochronology improves interpretations of tree-ring data for use in climate reconstruction, offering detailed insights into tree physiological responses and the mix of environmental and developmental controls on cell growth.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143114819","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}

引用次数: 0

Landscape Influences on Microclimate and Tree Growth Cessation in a Semi-Arid Montane Forest

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2025-01-11 DOI: 10.1029/2024JG008483

Fin Malone, Zachary H. Hoylman, Jia Hu, Kelsey G. Jencso

{"title":"Landscape Influences on Microclimate and Tree Growth Cessation in a Semi-Arid Montane Forest","authors":"Fin Malone, Zachary H. Hoylman, Jia Hu, Kelsey G. Jencso","doi":"10.1029/2024JG008483","DOIUrl":"https://doi.org/10.1029/2024JG008483","url":null,"abstract":"As climate change impacts the severity and frequency of drought, knowledge of hillslope-to-watershed scale ecohydrology is increasingly necessary to inform appropriate conservation, restoration, and management of forested ecosystems. In mountain environments, spatial patterns of water and energy organize forest productivity at plot, hillslope, and watershed scales. These microclimatic patterns are impacted by gradients in elevation, aspect, and local topographic convergence and divergence. In water-limited ecosystems, such patterns may be first-order drivers of tree growth. However, there is limited field-based research characterizing how seasonal drivers of forest growth may vary across complex terrain. Throughout the growing season, we measured soil moisture, vapor pressure deficit, soil and air temperatures, and radial growth at 27 Douglas-fir (Pseudotsuga menziesii) sites within Lubrecht Experimental Forest, Montana USA. Using these data, we assessed the influences of elevation, aspect, and local topographic position on hillslope-scale microclimates. These seasonal microclimates were then compared to the observed timing of tree growth cessation. Generally, trees located in high elevations, north-facing aspects, and convergent topographic positions were correlated with decreased temperatures, greater soil moisture, and reduced vapor pressure deficits, leading to later growth cessation. However, at the wettest positions, persistently saturated soil moisture conditions contributed to earlier cessation. Our findings highlight the landscape partitioning of forest microclimates and subsequently, their contribution to the spatial organization of growing seasons in semi-arid mountain watersheds. Lastly, we suggest that over longer timescales these seasonal microclimates influence tree growth year after year, contributing to the organization of cumulative forest growth previously observed within the watershed.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008483","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143114293","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}

引用次数: 0

Source Identification of Organic Carbon in Mountainous Reservoirs Sediments Using Stable Isotopes and n-Alkanes

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2025-01-10 DOI: 10.1029/2024JG008323

Yuan Zhou, Jianfeng Xu, Wei Ye, Kai Wang, Haiming Lu, Xianqiang Tang, Danyang Wang, Deti Xie, Jiupai Ni, Fangxin Chen

{"title":"Source Identification of Organic Carbon in Mountainous Reservoirs Sediments Using Stable Isotopes and n-Alkanes","authors":"Yuan Zhou, Jianfeng Xu, Wei Ye, Kai Wang, Haiming Lu, Xianqiang Tang, Danyang Wang, Deti Xie, Jiupai Ni, Fangxin Chen","doi":"10.1029/2024JG008323","DOIUrl":"https://doi.org/10.1029/2024JG008323","url":null,"abstract":"This study focuses on the sources of organic carbon (OC) in surface sediments of reservoirs in the mountainous regions, as well as their dynamics and contribution mechanisms in the carbon cycle. Spatial variations in organic carbon, n-alkanes, δ13C, and δ15N were analyzed, and a Bayesian isotope mixing model was applied to quantify the relative contributions of different OC sources. The results indicate that the concentration range of organic carbon in sediments is 0.88%–3.72%. The average concentration of long-chain n-alkanes is 3.69 μg/g, accounting for 71.4%, indicating that the main source of organic carbon is allochthonous organic carbon. In addition, the Bayesian mixture model results of carbon and nitrogen isotopes also indicate that allochthonous organic carbon is the main contributor. Specifically, sewage (33.1%), C₃ plants (27.1%), and soil organic carbon (19.9%) were identified as the dominant sources. This research highlights the influence of human activities, such as urbanization and agriculture, on OC dynamics and underscores the role of reservoirs in regulating OC transport. The findings provide critical insights into the mechanisms of OC sequestration in agricultural watersheds and offer valuable guidance for water resource management and ecological protection strategies in mountainous environments.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143113770","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}

引用次数: 0

Linking Changes in Plant Growth and Nutrient Stoichiometry With Nitrogen Enrichment in a Meadow Steppe

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2025-01-09 DOI: 10.1029/2024JG008270

Yinliu Wang, Guoxiang Niu, Guojiao Yang, Muqier Hasi, Ang Li, Jianguo Xue, Xiaotao Lü, Xingguo Han, Jianhui Huang

{"title":"Linking Changes in Plant Growth and Nutrient Stoichiometry With Nitrogen Enrichment in a Meadow Steppe","authors":"Yinliu Wang, Guoxiang Niu, Guojiao Yang, Muqier Hasi, Ang Li, Jianguo Xue, Xiaotao Lü, Xingguo Han, Jianhui Huang","doi":"10.1029/2024JG008270","DOIUrl":"https://doi.org/10.1029/2024JG008270","url":null,"abstract":"Exogenous nitrogen (N) inputs can significantly influence the availability of N and other nutrients in terrestrial ecosystems. However, the connections between soil nutrient dynamics following N enrichment and plant nutrient uptake as well as plant growth responses within a community remain underexplored. Here, we examined the effects of N addition on the dynamics of several macro and micronutrients in soil and three dominant plants on a meadow steppe in China. The results showed that (a) the exchangeable Ca and Mg in the soil initially increased when the N addition rate was lower than 10 g N m−2 yr−1 and then decreased at higher N addition rates (10–50 g N m−2 yr−1), whereas the available P and extractable Fe, Mn, and Cu remained relatively stable at low N addition rates but increased at high N addition rates. (b) The response of plant nutrient concentrations and the stoichiometry of these nutrients to N addition was not only species-specific but also showed marked differences especially for those micronutrients. (c) Species with lower variation in nutrient concentrations, such as Leymus chinensis (Lc) and Thermopsis lanceolata (Tl), exhibited increased (for Lc) or stable (for Tl) biomass after N addition, whereas species such as Carex duriuscula, with greater nutrient variability, experienced reduced biomass. These findings suggest that soil acidification induced by exogenous N inputs alters soil nutrient availability and further results in imbalanced plant nutrient uptake and stoichiometries, which will affect the dynamics and structures of plant communities under global change scenarios.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143113743","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}

引用次数: 0

Vertical Mixing, Light Penetration and Phosphorus Cycling Regulate Seasonal Algae Blooms in an Ice-Covered Dimictic Lake

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2025-01-08 DOI: 10.1029/2024JG008258

Alireza Ghane, Leon Boegman

{"title":"Vertical Mixing, Light Penetration and Phosphorus Cycling Regulate Seasonal Algae Blooms in an Ice-Covered Dimictic Lake","authors":"Alireza Ghane, Leon Boegman","doi":"10.1029/2024JG008258","DOIUrl":"https://doi.org/10.1029/2024JG008258","url":null,"abstract":"Many temperate lakes accumulate sediment derived orthophosphate (PO4) in their hypolimnion during late-summer deep-water hypoxia. In dimictic lakes, fall turnover will mix the PO4 through the water column. However, the fate and transport of this primary production limiting nutrient, during winter, is unknown. Does it remain available for the spring bloom, and why does it not trigger a fall bloom in many dimictic lakes? We conducted field observations and supplemented these with three-dimensional physical biogeochemical numerical simulations to gain a deeper understanding of PO4 transport and cycling within a small dimictic lake from 2011 to 2020. Our focus was particularly on the often-ice-covered winter season. We found, the sediment derived PO4 to be only a small portion (∼1%) of the total PO4 load, with most of the load from mineralization (49% ice free, 29% ice covered) and tributary inflows (22%). The accumulated hypolimnetic PO4 increased the water column concentration during fall turnover, but a fall bloom was not initiated, because the associated mixing transported phytoplankton beneath the photic zone. This PO4 remained available in the water column during winter and was combined with under-ice mineralized PO4 to initiate the spring bloom, in a thin stable layer beneath the ice, as solar radiation increased seasonally during spring.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008258","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143113036","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}

引用次数: 0

Hot or Not? An Evaluation of Methods for Identifying Hot Moments of Nitrous Oxide Emissions From Soils

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2025-01-07 DOI: 10.1029/2024JG008138

Emily R. Stuchiner, Jiacheng Xu, William C. Eddy, Evan H. DeLucia, Wendy H. Yang

{"title":"Hot or Not? An Evaluation of Methods for Identifying Hot Moments of Nitrous Oxide Emissions From Soils","authors":"Emily R. Stuchiner, Jiacheng Xu, William C. Eddy, Evan H. DeLucia, Wendy H. Yang","doi":"10.1029/2024JG008138","DOIUrl":"https://doi.org/10.1029/2024JG008138","url":null,"abstract":"Effectively quantifying hot moments of nitrous oxide (N2O) emissions from agricultural soils is critical for managing this potent greenhouse gas. However, we are challenged by a lack of standard approaches for identifying hot moments, including (a) determining thresholds above which emissions are considered hot moments, and (b) considering seasonal variation in the magnitude and frequency distribution of net N2O fluxes. We used one year of hourly N2O flux measurements from 16 autochambers that varied in flux magnitude and frequency distribution in a conventionally tilled maize field in central Illinois, USA, to compare three approaches to identify hot moment thresholds: standard deviations (SD) above the mean, 1.5x the interquartile range (IQR), and isolation forest (IF) identification of anomalous values. We also compared these approaches on seasonally subdivided data (early, late, and non-growing seasons) versus the whole year. Our analyses revealed that 1.5x IQR method best identified N2O hot moments. In contrast, using 2 or 4 SD both yielded hot moment threshold values too high, and IF yielded threshold values too low, leading to missed N2O hot moments or low net N2O fluxes mischaracterized as hot moments, respectively. Furthermore, seasonally subdividing the data set not only facilitated identification of smaller hot moments in the late- and non-growing seasons when N2O hot moments were generally smaller but it also increased hot moment threshold values in the early growing season when N2O hot moments were larger. Consequently, of the methods evaluated here, we recommend using the 1.5x IQR method on whole year data sets to identify N2O hot moments.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008138","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143113202","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}

引用次数: 0