Agricultural and Forest Meteorology最新文献

{"title":"Contributions of diffusion and ebullition processes to total methane fluxes from a subtropical rice paddy field in southeastern China","authors":"Tingting Zhu, Yanlian Zhou, Weimin Ju, Yu Mao, Rui Xie","doi":"10.1016/j.agrformet.2025.110504","DOIUrl":"https://doi.org/10.1016/j.agrformet.2025.110504","url":null,"abstract":"Diffusion and ebullition are two important processes regulating methane (CH₄) emission from rice fields. Studies on diffusion and ebullition CH₄ fluxes can provide the scientific foundation for better investigating the impact of climate change on CH₄ emission. In this study, we measured CH₄ fluxes using the static chamber (CC) and eddy covariation (EC) methods over a subtropical rice paddy field in southeastern China in 2021 and 2022. In addition, the diffusive and ebullition fluxes of CH₄ were quantified according to CC measurements and estimations from EC data using the wavelet analysis (WW) method. The total and diffusive fluxes obtained by CC and WW methods were both significantly correlated at the hourly and daily scales. However, the correlation between ebullition fluxes obtained by CC and WW methods was insignificant. The CC measurements indicated that the dominant role of the diffusive process in contributing to CH₄ fluxes, accounting for 89 % and 91 % of the total CH₄ flux in rice paddy in 2021 and 2022, respectively. The total, diffusive, and ebullition CH₄ fluxes all peaked at 13:00. Air temperature and water table depth acted as the most important factors regulating the seasonal variations of total and diffusive CH₄ fluxes at this rice field. Overall, the study provided valuable insights into the CH₄ flux dynamics in rice paddies, which can inform the development of process-based models for simulating CH₄ emission in rice paddies.","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"9 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impact of photovoltaic plants on dryland vegetation phenology revealed by time-series remote sensing images","authors":"Zilong Xia ,&nbsp;Yingjie Li ,&nbsp;Shanchuan Guo ,&nbsp;Encai Bao ,&nbsp;Bo Yuan ,&nbsp;Ruishan Chen ,&nbsp;Pengfei Tang ,&nbsp;Chenghan Yang ,&nbsp;Peijun Du","doi":"10.1016/j.agrformet.2025.110505","DOIUrl":"10.1016/j.agrformet.2025.110505","url":null,"abstract":"<div><div>To limit global warming, solar energy production is expanding in drylands globally. This study investigated phenological changes caused by photovoltaic (PV) plants in China's drylands using satellite-derived metrics. The results show that the deployment of PV plants has advanced the start of the growing season (SOS) by a median of 13.7 days, while extending the length of the growing season (LOS) by a median of 16.3 days in arid and semi-arid drylands. Soil moisture was the main factor influencing phenological changes in these regions, indicating that the evaporation-reducing effect of PV panels strongly regulates phenology. In sub-humid drylands, solar radiation was the primary factor, with shading effects delaying SOS and shortening LOS. The phenology of PV plants in these regions did not show significant changes, possibly because the shading effect of the PV panels delays SOS and shortens LOS, which may counteract the effects of increased soil moisture on phenology.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"367 ","pages":"Article 110505"},"PeriodicalIF":5.6,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143653867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nigeria vegetation trend during recent West African monsoon season and the near future implications in CORDEX-Africa","authors":"Ugochukwu K. Okoro ,&nbsp;Chijioke U. Opara ,&nbsp;Hyacinth C. Nnamchi ,&nbsp;Wen Chen","doi":"10.1016/j.agrformet.2025.110499","DOIUrl":"10.1016/j.agrformet.2025.110499","url":null,"abstract":"<div><div>This study investigated the impact of recent West African monsoon seasonal rainfall on the vegetation trend in Nigeria. Using Mann-Kendall test, the satellite estimates revealed increasing trends in the mean Normalized Difference Vegetation Index (NDVI) at 95 % in area of the location between 1981 and 2020 with statistical significance (at<span><math><mrow><mspace></mspace><mi>α</mi><mo>≤</mo><mn>0.5</mn></mrow></math></span> levels of significance) in the south-western States. The 6-month Standardized Precipitation Index (SPI) from the Climate Research Unit (CRU) observational rainfall within the same period indicated increasing trends at 73 % of the area with statistical significance (at <span><math><mrow><mi>α</mi><mo>≤</mo><mn>0.5</mn></mrow></math></span> levels of significance) in the northern States above the 9° N latitude. From the temporal correlations between the seasonal rainfall and vegetation trends, there was significant (at 95 % confidence level from the <em>t</em>-test) positive characteristic impact on 89 % of the area. The CORDEX-Africa historical experiment outputs (1981–2005) of the selected models and the ensemble mean revealed strong correlation values with high normalized RMSE when representing the seasonal rainfall simulation. The bias-corrected output (2006–2020) in the RCP 8.5 experiment showed notably enhanced representation quality of the models and the ensemble mean, with 87 % of the area demonstrating “reasonable performance” efficiency. The 6-month SPI projection from 2021 to 2050 indicated positive trends in 84 % of the area. Indeed, the relative percentage difference between projected and baseline trends compellingly suggests a decrease in seasonal rains by 2050, intensifying the demand on vegetation and introducing additional climate challenges.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"367 ","pages":"Article 110499"},"PeriodicalIF":5.6,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143640254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Linking soil extracellular enzymes with soil respiration under altered litter inputs","authors":"Hao Chen ,&nbsp;Qianhao Xu ,&nbsp;Kees Jan van Groenigen ,&nbsp;Bruce A. Hungate ,&nbsp;Pete Smith ,&nbsp;Dejun Li ,&nbsp;Daryl L. Moorhead ,&nbsp;Brooke B. Osborne ,&nbsp;Zilong Ma ,&nbsp;Jørgen E. Olesen ,&nbsp;Chaoqun Wang ,&nbsp;Ji Liu ,&nbsp;Xibin Sun ,&nbsp;Chengjin Chu ,&nbsp;Ji Chen","doi":"10.1016/j.agrformet.2025.110503","DOIUrl":"10.1016/j.agrformet.2025.110503","url":null,"abstract":"<div><div>Climate and land-use changes have altered both litter quality and quantity, with cascading impacts on soil respiration (SR). Soil extracellular enzymes (EEs) like cellulase and ligninase are crucial for deconstructing plant litter because they convert polymers into monomers. However, whether and how changes in litter inputs influence soil cellulase and ligninase activities as well as the implications for SR remain poorly understood. We conducted a global meta-analysis of 827 observations on the responses of SR and soil cellulase and ligninase activities to litter addition and litter removal. Litter addition significantly increased cellulase activity by 25 %, whereas litter removal decreased it by 26 %. Neither litter addition nor litter removal affected ligninase activity. Changes in cellulase activity correlated positively with SR under both litter addition and litter removal, but no such relationship was found for ligninase activity. These results indicate that changes in litter inputs affect SR primarily by affecting the microbial decomposition of readily decomposable rather than more structurally complex carbon pools. In addition, the effects of changes in litter inputs on cellulase activity decreased with treatment duration, suggesting that the long-term effects of changes in litter inputs on SR might be smaller than previously thought. Our results underscore the dominant role of cellulase in mediating the responses of SR to altered litter inputs. Integrating cellulase responses to altered litter inputs into Earth system models could improve the representation of microbial processes and refine the predictions of soil carbon dynamics.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"367 ","pages":"Article 110503"},"PeriodicalIF":5.6,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143640255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tree-ring width series of synchronously growing trees' classes effectively optimizes their climatic signal","authors":"Jing Yang ,&nbsp;Ouya Fang ,&nbsp;Hengfeng Jia ,&nbsp;Jiacheng Zheng ,&nbsp;Yumei Mu ,&nbsp;Paolo Cherubini","doi":"10.1016/j.agrformet.2025.110500","DOIUrl":"10.1016/j.agrformet.2025.110500","url":null,"abstract":"<div><div>The high variability in forest responses to climate changes is often due to the different ways in which individual trees transmit climate signals. This raises the problem that tree-ring chronologies sometimes lack a strong explanation for climate variations. This study aims to efficiently optimize the climatic signals from tree rings based on the method of classifying trees according to their synchronous growth.</div><div>Following dendroclimatological methods, we obtained tree-ring data from 190 juniper (<em>Juniperus przewalskii</em>) samples in the Qilian Mountains, northeast of the Qinghai-Tibetan Plateau. To explore the growth-climate relationship, we classified trees into high- and low-synchronous groups based on their synchrony of annual radial growth. We found that the tree growth of those two groups has different responses to climate factors.</div><div>The results showed that the chronology of high-synchronous growth was significantly and positively correlated with precipitation and moisture conditions during the early summer, while the chronology of low-synchronous growth was significantly and positively correlated with winter maximum temperatures. Compared with the regional standard chronology, the classified chronologies enhanced the extraction of climate information.</div><div><em>Synthesis.</em> We utilize the growth inconsistency among individual trees to develop a classification method more effectively selects upstream trees, thereby capturing the key climatic signals embedded in tree radial growth. This approach enables a more precise exploration of the relationship between tree-ring growth and climatic factors, with potentially significant implications for improving the accuracy of future climate reconstructions.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"366 ","pages":"Article 110500"},"PeriodicalIF":5.6,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence of 3D canopy structure on modelled photosynthesis","authors":"Megan A. Stretton ,&nbsp;Tristan Quaife ,&nbsp;Phil Wilkes ,&nbsp;Mat Disney","doi":"10.1016/j.agrformet.2025.110437","DOIUrl":"10.1016/j.agrformet.2025.110437","url":null,"abstract":"<div><div>Vegetation is one of the largest terrestrial sinks of atmospheric carbon dioxide, driven by the balance between photosynthesis and respiration. Understanding the processes behind this net flux is critical, as it influences the global atmospheric carbon dioxide concentration and hence climate change. A key factor determining the carbon flux into the land surface is the absorption of light by vegetation, used to drive photosynthesis. However, climate models commonly represent vegetation canopies as homogenous slabs of randomly positioned leaves. By contrast, real forests generally exhibit large amounts of 3-dimensional heterogeneity.</div><div>We examine the impact of including measured 3D vegetation canopy structure on modelled gross primary productivity (GPP) by looking at how leaf area is distributed. We introduce a methodology to calculate GPP using output from the explicit Discrete Anisotropic Radiative Transfer (DART) model, following the approach commonly used in land surface schemes. The sensitivity of modelled GPP to canopy structure assumptions in Earth system models is explored, using 3D structural information derived from six forest plots using Terrestrial Lidar Scanning (TLS) data. Here, we use the spatial resolution as a proxy for the canopy structure, with the very coarsest simulations containing no spatial variability in leaf location, with variability introduced as the resolution of the simulations becomes finer. In almost all cases, the simulated GPP is reduced, and with the finest resolution this is up to 25 %. This contrasts with recent studies showing the opposite effect. In the few cases where the GPP increased, this was only marginal (&lt; 2.5 %). These results suggest that not accounting for the impact of 3-dimensional canopy structure could lead to significant biases in land surface models, particularly in forest's contribution to the global carbon budget. We suggest that vegetation structure is considered, explicitly or through a correction factor, alongside a comparison to existing clumping approaches.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"366 ","pages":"Article 110437"},"PeriodicalIF":5.6,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143618163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unravelling the 3D thermal environment differences between forest center and edge: A case study on 22 urban forests in Hefei city, China","authors":"Qingqing Ma ,&nbsp;Yongxian Su ,&nbsp;Xiuzhi Chen ,&nbsp;Xiu Meng ,&nbsp;Fengyu Zhang ,&nbsp;Raffaele Lafortezza ,&nbsp;Yiyong Li","doi":"10.1016/j.agrformet.2025.110481","DOIUrl":"10.1016/j.agrformet.2025.110481","url":null,"abstract":"<div><div>Urban forests with various structures can bring considerable but divergent biophysical cooling and humidification effects on their local climate. Thus, it is crucial to unravel the 3D thermal environment within urban forests and their relationship with forest structure, which are helpful for the urban forest planning and design. In this study, we continuously observed the air temperature (T_a) at different vertical layers from canopy to land surface as well as the soil surface temperature (T_s) from the forest center to 5 m outside the forest edge across 22 urban forests in Hefei city, China. Indicators of forest structure such as tree height, diameter at breast height (DBH), crown diameter and leaf traits were associated with their 3D thermal environments for exploring the underlying mechanisms. We found that T_s was 1.43 °C lower than the understory air temperature (T_{a understory}) in forest center but 10.90 °C higher than T_{a understory} outside the forest. Additionally, tree height largely influenced the buffering distance from forests center to the places with T_s = T_{a understory} (L_{Ts=Ta understory Lcenter}), being 4.41 m, 5.80 m and 7.75 m in short (&lt; 7 m), medium (7–9 m) and tall (&gt;9 m) canopy forests, respectively. The temperature difference between forest center and 5 m outside the forest (ΔTemperature) varied significantly at different vertical layers, with ΔT_s greater than 10 °C, ΔT_{a understory} and ΔT_{a bottom canopy} at around 2 °C, and no difference for ΔT_{a upper canopy}. Regression analysis showed different relationships of forest structure and leaf traits with ΔTemperature between vertical layers. Tree height, forest area and DBH showed significant positive relationships with L_{Ts=Ta understory Lcenter}. The study, for the first time, demonstrate the 3D thermal environments of urban forests, quantify the role of forest structure and leaf traits in predicting forest cooling.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"366 ","pages":"Article 110481"},"PeriodicalIF":5.6,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143627748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fire increases the risk of hydraulic failure of woody species: Evidence from an experiment and a meta-analysis","authors":"Rui Zhang ,&nbsp;Yaxin Zhang ,&nbsp;Aolin Niu ,&nbsp;Chuankuan Wang ,&nbsp;Ying Jin","doi":"10.1016/j.agrformet.2025.110495","DOIUrl":"10.1016/j.agrformet.2025.110495","url":null,"abstract":"<div><div>Fire-induced damage to plant tissues can affect the capacities for water transport, carbon fixation, and carbon utilization, potentially resulting in immediate or delayed post-fire tree mortality. In this study, we measured leaf and stem hydraulic (pressure-volume traits, hydraulic conductivity, and embolism resistance) and economic (photosynthesis, non-structural carbohydrates, and nutrients) traits of <em>Larix gmelinii</em> following fire events in northeastern China. To obtain a comprehensive understanding of fire effects on tree hydraulics and economics, we also conducted a meta-analysis to explore the global universal responses of tree carbon-water physiological traits to fire. Our experimental study showed that fire led to reductions in stem embolism resistance, hydraulic safety margin, vulnerability segmentation margin, and leaf non-structural carbohydrates, implying that fire would increase the vulnerability to drought and diminish the ability to repair embolism. Our global meta-analysis further validated the reduction in stem embolism resistance, while the hydraulic traits of angiosperms were more sensitive to fire than those of gymnosperms. Furthermore, angiosperms and gymnosperms also showed opposite responses to fire in photosynthetic rate and stomatal conductance, with positive responses in angiosperms and negative responses in gymnosperms. Therefore, angiosperms typically up-regulate photosynthetic rates and stomatal conductance to enhance carbon assimilation, even at the risk of hydraulic failure after fire. In contrast, gymnosperms, including <em>Larix gmelinii</em>, tend to close stomata to compensate the increased stem embolism vulnerability and preserve hydraulic safety following fire. Overall, by combining an experimental study with a meta-analysis, we suggest that fire increases the risk of hydraulic failure in woody species.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"366 ","pages":"Article 110495"},"PeriodicalIF":5.6,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143590173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lower carbon uptake rates resulting from converting wooded Cerrado to pasture-dominated agricultural area in the Brazilian savanna","authors":"Yuqing Zhao ,&nbsp;David Holl ,&nbsp;Jamil A.A. Anache ,&nbsp;Alex N.A. Kobayashi ,&nbsp;Edson Wendland","doi":"10.1016/j.agrformet.2025.110465","DOIUrl":"10.1016/j.agrformet.2025.110465","url":null,"abstract":"<div><div>Agricultural expansion in the Brazilian Cerrado ecoregion has been causing extensive land use and land cover changes (LULCC), drastically shifting the carbon cycle dynamics of the affected ecosystems. However, accurate in situ observations of the net ecosystem exchange of carbon dioxide (NEE) from wooded Cerrado (<em>Cerrado sensu stricto</em>) as well as from post-conversion agricultural landscapes are lacking, with the limited amount of impact assessments in the literature being primarily based on remotely sensed data. This study presents a multi-annual time series of temporal high-resolution eddy covariance carbon dioxide fluxes, measured on the border between a wooded Cerrado and a post-conversion agricultural area, primarily used as a pasture, in southeastern Brazil. We investigated multiple setups of NEE partitioning methods to separate NEE into its components gross primary production (GPP) and total ecosystem respiration (TER). We combined these component partitioning models with source area partitioning methods to estimate component fluxes for the two contrasting ecosystems within the tower footprint. Model results were compared against remotely sensed vegetation indices and flux data from similar ecosystems. We found that converting native wooded Cerrado to a pasture-dominated agricultural area decreased the landscape’s NEE carbon (NEE-C) uptake by up to 494 g m^-2 yr^-1 (73 %). The wooded Cerrado had an annual cumulative NEE-C of -639 ± 20 g m^-2 yr^-1 and -673 ± 19 g m^-2 yr^-1 in 2019 and 2020, respectively. In comparison, the pasture had lower annual cumulative NEE-C of -146 ± 39 g m^-2 yr^-1 and -179 ± 38 g m^-2 yr^-1 in the same years. The pasture exhibited lower light use efficiency (LUE) and NEE-C uptake in the dry season, resulting in lower annual NEE-C uptake. Additionally, the pasture showed greater sensitivity to precipitation changes, leading to higher seasonal variations in carbon dioxide fluxes.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"366 ","pages":"Article 110465"},"PeriodicalIF":5.6,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143590174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global distribution of leaf maximum carboxylation rate derived from the TROPOMI solar-induced chlorophyll fluorescence data","authors":"Xiaoping Wang ,&nbsp;Jing M. Chen ,&nbsp;Liming He ,&nbsp;Weimin Ju","doi":"10.1016/j.agrformet.2025.110496","DOIUrl":"10.1016/j.agrformet.2025.110496","url":null,"abstract":"<div><div>Photosynthesis plays an important role in the terrestrial carbon cycle and is often studied using terrestrial biosphere models (TBMs). The maximum carboxylation rate at 25 °C (V_cmax25) is a key parameter in TBMs, and yet the information on the spatiotemporal distribution of this parameter is uncertain. In this study, we retrieved the global distribution of V_cmax25 at 0.25° resolution based on TROPOMI-observed solar-induced chlorophyll fluorescence (SIF) and meteorological forcing data using a parameter optimization technique. This study improves global mapping of V_cmax25 using TROPOMI's SIF and MODIS photochemical reflectance index (PRI) for accurate GPP estimation by sunlit leaves in the following aspects: the previous method relied on an empirical estimation of the ratio of SIF per unit sunlit leaf area to that per unit shaded leaf area (<em>β</em>), while <em>β</em> here was derived from a look-up table (LUT) constructed using the Soil-Canopy Observation of Photosynthesis and Energy (SCOPE) model. Validated at two flux tower sites, the LUT method explained most of the variation in <em>β</em> with <em>R²</em> = 0.71 and 0.67, RMSE=0.19 and 0.15 and Slope=0.84 and 0.70 for two ground validation sites. We calculated the global ratio of SIF from sunlit to that from shaded leaves (<em>SIF_ratio</em>), and found that the <span><math><mrow><mi>S</mi><mi>I</mi><mi>F</mi><mo>_</mo><mi>r</mi><mi>a</mi><mi>t</mi><mi>i</mi><mi>o</mi></mrow></math></span> had a strong spatio-temporal variability with a global average of approximately 4.6, and that the contribution of SIF from shaded leaves to the canopy total was &lt;20 %. The optimized V_cmax25 from TROPOMI was validated against V_cmax25 derived from concurrent flux data at 27 sites distributed globally using an independent method (R² = 0.39 - 0.65, RMSE = 6.47 - 21.74 μmol m^-2 s^-1 and rRMSE =0.14–0.36). Based on the improved global V_cmax25 map, we found that, spatially, V_cmax25 varies significantly with latitude and between- and within-plant function types (PFTs), and temporally, it has strong seasonal variation in all PFTs except evergreen broadleaf forests. The new global V_cmax25 dataset would be useful for improving terrestrial GPP modelling from the current state of the art of using constant V_cmax25 values by plant functional type.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"366 ","pages":"Article 110496"},"PeriodicalIF":5.6,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}