Pub Date : 2025-02-05DOI: 10.1016/j.agrformet.2025.110422
Dorianis M. Perez , Jesse M. Canfield , Rodman R. Linn , Kevin Speer
Vorticity is a key characteristic of flow patterns that determine wildland fire behavior, frontal evolution, and wind-canopy interaction. Investigating the role of vorticity in the flow fields around vegetation can help us better understand fire-atmosphere feedback and the influences of vegetation on this feedback. In modeling vorticity, “perhaps the greatest knowledge gap exists in understanding which terms in the vorticity equation dominate [...] (and) when one or the other might dominate” (Potter, 2012). In this study, we investigate the role of vorticity in boundary layer dynamics and canopy/forest edge effects using HIGRAD/FIRETEC, a three-dimensional, two-phase transport model that conserves mass, momentum, energy, and chemical species. A vorticity transport equation was derived and discretized. Simulations were performed over a cuboidal homogeneous canopy surrounded by surface vegetation. This derivation led to the discovery of a drag tilting and stretching term, which shows that gradients in the aerodynamic drag of the vegetation, tied to heterogeneities in surface area-to-volume ratio, play an important role in the generation of vorticity. Results from the vorticity budget analysis show that the drag tilting and stretching term contributes significantly in the areas where these gradients are present, namely the edges of the canopy.
{"title":"Characterizing turbulence at a forest edge: A vorticity budget analysis around a canopy","authors":"Dorianis M. Perez , Jesse M. Canfield , Rodman R. Linn , Kevin Speer","doi":"10.1016/j.agrformet.2025.110422","DOIUrl":"10.1016/j.agrformet.2025.110422","url":null,"abstract":"<div><div>Vorticity is a key characteristic of flow patterns that determine wildland fire behavior, frontal evolution, and wind-canopy interaction. Investigating the role of vorticity in the flow fields around vegetation can help us better understand fire-atmosphere feedback and the influences of vegetation on this feedback. In modeling vorticity, “perhaps the greatest knowledge gap exists in understanding which terms in the vorticity equation dominate [...] (and) when one or the other might dominate” (<span><span>Potter, 2012</span></span>). In this study, we investigate the role of vorticity in boundary layer dynamics and canopy/forest edge effects using HIGRAD/FIRETEC, a three-dimensional, two-phase transport model that conserves mass, momentum, energy, and chemical species. A vorticity transport equation was derived and discretized. Simulations were performed over a cuboidal homogeneous canopy surrounded by surface vegetation. This derivation led to the discovery of a drag tilting and stretching term, which shows that gradients in the aerodynamic drag of the vegetation, tied to heterogeneities in surface area-to-volume ratio, play an important role in the generation of vorticity. Results from the vorticity budget analysis show that the drag tilting and stretching term contributes significantly in the areas where these gradients are present, namely the edges of the canopy.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"363 ","pages":"Article 110422"},"PeriodicalIF":5.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143124403","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}
Pub Date : 2025-02-04DOI: 10.1016/j.agrformet.2025.110432
Hao Cui , Lei Wang , Zhiheng Du , Zhiqiang Wei , Cunde Xiao
Continuous global warming exacerbates the worldwide hydrological cycle, and alterations in precipitation patterns affect the carbon cycle in grassland ecosystems. The consistency of grassland ecosystem responses to precipitation fluctuations remains unclear, despite extensive research on carbon cycling responses in various ecosystems. Here, we collected data from 109 studies (3129 observations in total) to assess the response of carbon cycle variables to precipitation changes in three grassland types (desert grassland, arid grassland, and wet grassland) at a global scale. The results show that the carbon cycle of grasslands had a wide asymmetric response to changes in precipitation. Increased precipitation promoted carbon input and carbon output in the three grassland types, whereas decreased precipitation inhibited both processes. The response of soil respiration (Rs) to increased precipitation was the lowest in the wet grassland (16.51 %) and the highest in the desert grassland (28.72 %), whereas the response to decreased precipitation was the highest in the arid grassland (-34 %) and the lowest in the wet grassland (-15.37 %). Interestingly, autotrophic respiration (Ra) responded more to increased precipitation than to decreased precipitation, with wet grasslands exhibiting a 10 times greater response. Moreover, the net ecosystem exchange (NEE) of arid grasslands responded more strongly to decreased precipitation, whereas the NEE of desert grasslands responded more strongly to increased precipitation. The natural climate of grasslands affected their response to precipitation management. As the treatment time increased, the response of soil respiration in the desert grasslands gradually decreased, whereas the response in the wet grasslands gradually increased. There was no significant temporal trend in arid grasslands. The natural climate of grassland ecosystems affected their response to precipitation treatments, particularly grassland moisture conditions, which may be the main limiting factor regulating the response of grassland ecosystems to the carbon cycle.
{"title":"Precipitation trends cause large uncertainties in grassland carbon budgets—a global meta-analysis","authors":"Hao Cui , Lei Wang , Zhiheng Du , Zhiqiang Wei , Cunde Xiao","doi":"10.1016/j.agrformet.2025.110432","DOIUrl":"10.1016/j.agrformet.2025.110432","url":null,"abstract":"<div><div>Continuous global warming exacerbates the worldwide hydrological cycle, and alterations in precipitation patterns affect the carbon cycle in grassland ecosystems. The consistency of grassland ecosystem responses to precipitation fluctuations remains unclear, despite extensive research on carbon cycling responses in various ecosystems. Here, we collected data from 109 studies (3129 observations in total) to assess the response of carbon cycle variables to precipitation changes in three grassland types (desert grassland, arid grassland, and wet grassland) at a global scale. The results show that the carbon cycle of grasslands had a wide asymmetric response to changes in precipitation. Increased precipitation promoted carbon input and carbon output in the three grassland types, whereas decreased precipitation inhibited both processes. The response of soil respiration (Rs) to increased precipitation was the lowest in the wet grassland (16.51 %) and the highest in the desert grassland (28.72 %), whereas the response to decreased precipitation was the highest in the arid grassland (-34 %) and the lowest in the wet grassland (-15.37 %). Interestingly, autotrophic respiration (Ra) responded more to increased precipitation than to decreased precipitation, with wet grasslands exhibiting a 10 times greater response. Moreover, the net ecosystem exchange (NEE) of arid grasslands responded more strongly to decreased precipitation, whereas the NEE of desert grasslands responded more strongly to increased precipitation. The natural climate of grasslands affected their response to precipitation management. As the treatment time increased, the response of soil respiration in the desert grasslands gradually decreased, whereas the response in the wet grasslands gradually increased. There was no significant temporal trend in arid grasslands. The natural climate of grassland ecosystems affected their response to precipitation treatments, particularly grassland moisture conditions, which may be the main limiting factor regulating the response of grassland ecosystems to the carbon cycle.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"363 ","pages":"Article 110432"},"PeriodicalIF":5.6,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143083198","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}
Pub Date : 2025-02-03DOI: 10.1016/j.agrformet.2025.110426
James B Manson , Matthew D Denton , Lachlan Lake , Victor O Sadras
Environmental characterisation provides a useful summary of a major source of variation in grain yield. Environments consist of water and photothermal regimes that covary in time and space, but previous characterisations have focussed on single-variable regimes such as drought, or downplayed the temporal pattern of multivariate regimes. Season-long, multivariate characterisations are needed to more realistically represent the complex growing conditions that crops encounter. We conducted two studies on faba bean, an important source of plant protein, in Australia, its largest exporter. From a database of yield with 299 variety trials, Study 1 tested the timing and strength of the association of seed yield with maximum and minimum temperature, heat stress, frost, solar radiation, vapour pressure deficit and simulated water supply:demand. Study 2 used cluster analysis of 30,096 simulated crops (1957–2022, three sowing dates, two varieties, 76 locations) to determine environment types for these variables, individually and combined. We tested the real-world relevance of the environment types with the seed yield data of Study 1. Water supply:demand, maximum temperature and vapour pressure deficit had the strongest links to grain yield in both studies. We identified four multivariate environment types that ranged from syndromes of ‘wet, cool and low evaporative demand’ to ‘dry, hot and high evaporative demand’. From least to most stressful environment type, median seed yield reduced by 62 %. Frequency of environment types varied with location, sowing date and variety, highlighting the potential value of earlier sowing and phenology for a large part of the country. From 1963–1992 compared with 1993–2022, the frequency of stressful environment types increased by 4 to 9 %, highlighting the need to adapt to a challenging future climate. Our findings can inform breeding, management and research of faba bean in Australia and beyond, and our multivariate method can be applied to other crops and environments.
{"title":"An integrated, multivariate characterisation of water and photothermal regimes for faba bean in Australia","authors":"James B Manson , Matthew D Denton , Lachlan Lake , Victor O Sadras","doi":"10.1016/j.agrformet.2025.110426","DOIUrl":"10.1016/j.agrformet.2025.110426","url":null,"abstract":"<div><div>Environmental characterisation provides a useful summary of a major source of variation in grain yield. Environments consist of water and photothermal regimes that covary in time and space, but previous characterisations have focussed on single-variable regimes such as drought, or downplayed the temporal pattern of multivariate regimes. Season-long, multivariate characterisations are needed to more realistically represent the complex growing conditions that crops encounter. We conducted two studies on faba bean, an important source of plant protein, in Australia, its largest exporter. From a database of yield with 299 variety trials, Study 1 tested the timing and strength of the association of seed yield with maximum and minimum temperature, heat stress, frost, solar radiation, vapour pressure deficit and simulated water supply:demand. Study 2 used cluster analysis of 30,096 simulated crops (1957–2022, three sowing dates, two varieties, 76 locations) to determine environment types for these variables, individually and combined. We tested the real-world relevance of the environment types with the seed yield data of Study 1. Water supply:demand, maximum temperature and vapour pressure deficit had the strongest links to grain yield in both studies. We identified four multivariate environment types that ranged from syndromes of ‘wet, cool and low evaporative demand’ to ‘dry, hot and high evaporative demand’. From least to most stressful environment type, median seed yield reduced by 62 %. Frequency of environment types varied with location, sowing date and variety, highlighting the potential value of earlier sowing and phenology for a large part of the country. From 1963–1992 compared with 1993–2022, the frequency of stressful environment types increased by 4 to 9 %, highlighting the need to adapt to a challenging future climate. Our findings can inform breeding, management and research of faba bean in Australia and beyond, and our multivariate method can be applied to other crops and environments.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"363 ","pages":"Article 110426"},"PeriodicalIF":5.6,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077123","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}
Pub Date : 2025-02-01DOI: 10.1016/j.agrformet.2025.110429
Zhaoguo Wang , Chuankuan Wang
The role of carbon starvation in drought-induced plant mortality remains a topic of debate. This underscores the need for a comprehensive understanding of the regulation of non-structural carbohydrates (NSCs) during drought and subsequent recovery. To this end, we compiled 226 articles and conducted a meta-analysis to examine the responses of NSCs to drought and rewatering, as well as the influences of plant functional type, drought magnitude, duration and climate variables. Overall, drought primarily reduced NSC concentrations in leaves, with negligible impacts on stems and roots. While starch concentrations declined, soluble sugar concentrations, including fructose and glucose, increased. Leaf NSC concentration returned to control levels after rewatering, whereas reductions in NSC concentrations in stems and roots were observed in the post-drought period. Herbaceous plants exhibited greater changes in leaf and root soluble sugar concentrations compared to woody plants. Gymnosperms experienced more significant root NSC reductions than angiosperms. Unlike deciduous angiosperms, evergreen angiosperms showed decreases in stem and root NSC concentrations during drought. Starch concentrations in mature woody plants remained relatively stable during drought, whereas they decreased in seedlings and saplings. The negative effects of drought on stem and root starch concentrations diminished with prolonged drought. Increases in soluble sugar concentrations in leaves were more pronounced in drier environments. These findings highlight the complex dynamics of NSCs during drought and subsequent recovery, emphasizing the need to consider plant functional types, drought characteristics, and climatic conditions when assessing the role of carbon starvation in drought-induced plant mortality.
{"title":"Dynamics of nonstructural carbohydrates during drought and subsequent recovery: A global meta-analysis","authors":"Zhaoguo Wang , Chuankuan Wang","doi":"10.1016/j.agrformet.2025.110429","DOIUrl":"10.1016/j.agrformet.2025.110429","url":null,"abstract":"<div><div>The role of carbon starvation in drought-induced plant mortality remains a topic of debate. This underscores the need for a comprehensive understanding of the regulation of non-structural carbohydrates (NSCs) during drought and subsequent recovery. To this end, we compiled 226 articles and conducted a meta-analysis to examine the responses of NSCs to drought and rewatering, as well as the influences of plant functional type, drought magnitude, duration and climate variables. Overall, drought primarily reduced NSC concentrations in leaves, with negligible impacts on stems and roots. While starch concentrations declined, soluble sugar concentrations, including fructose and glucose, increased. Leaf NSC concentration returned to control levels after rewatering, whereas reductions in NSC concentrations in stems and roots were observed in the post-drought period. Herbaceous plants exhibited greater changes in leaf and root soluble sugar concentrations compared to woody plants. Gymnosperms experienced more significant root NSC reductions than angiosperms. Unlike deciduous angiosperms, evergreen angiosperms showed decreases in stem and root NSC concentrations during drought. Starch concentrations in mature woody plants remained relatively stable during drought, whereas they decreased in seedlings and saplings. The negative effects of drought on stem and root starch concentrations diminished with prolonged drought. Increases in soluble sugar concentrations in leaves were more pronounced in drier environments. These findings highlight the complex dynamics of NSCs during drought and subsequent recovery, emphasizing the need to consider plant functional types, drought characteristics, and climatic conditions when assessing the role of carbon starvation in drought-induced plant mortality.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"363 ","pages":"Article 110429"},"PeriodicalIF":5.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071576","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}
Japanese cypress (Chamaecyparis obtusa Sieb. et Zucc.) is an evergreen conifer native to Japan and widely distributed in East Asia. Evergreen forests in temperate regions are usually exposed to high solar radiation and low temperatures during winter, a combination of stresses that can negatively impact leaf photosynthetic capacity. In response to excessive light energy stress under cold temperatures, Japanese cypress canopies exhibit a reversible color change associated with several photoprotective mechanisms known as “winter leaf reddening.” Here, several vegetation indices (VIs), including the photochemical reflectance index (PRI), rhodoxanthin index (RI), chlorophyll/carotenoid ratio index (CCI), triangular PRI index (tri-PRI), and red-green vegetation index (RGVI) were utilized to track the influence of winter leaf reddening and photoprotection on canopy-scale light-use efficiency (LUE) determined by the eddy covariance technique. Seasonal changes in VIs, environmental factors, and LUE in Japanese cypress canopies between 2017 and 2021 indicated that VIs could detect the phenology and LUE changes during winter leaf reddening. Our results suggest that winter leaf reddening occurrence is driven by prolonged low temperatures, and accompanied by dynamic xanthophyll cycle suppression, rhodoxanthin accumulation, and LUE reduction. Once stressful conditions are released, rhodoxanthin quickly decomposes and the remaining xanthophyll pigment may lead the canopy reddish-brown to persist longer. The integration of remote sensing and eddy covariance methods facilitates the validation of traditional results observed at the leaf scale within the context of the canopy scale, offering insights into how vegetation adjusts photosynthesis in response to environment stress.
{"title":"Winter leaf reddening and photoprotection accessed by vegetation indices and its influence on canopy light-use efficiency of a Japanese cypress (Chamaecyparis obtusa) forest","authors":"Siyu Chen , Yoshiko Kosugi , Linjie Jiao , Ayaka Sakabe , Daniel Epron , Tatsuro Nakaji , Hibiki Noda , Kouki Hikosaka , Kenlo Nishida Nasahara","doi":"10.1016/j.agrformet.2025.110427","DOIUrl":"10.1016/j.agrformet.2025.110427","url":null,"abstract":"<div><div>Japanese cypress (<em>Chamaecyparis obtusa</em> Sieb<em>.</em> et Zucc.) is an evergreen conifer native to Japan and widely distributed in East Asia. Evergreen forests in temperate regions are usually exposed to high solar radiation and low temperatures during winter, a combination of stresses that can negatively impact leaf photosynthetic capacity. In response to excessive light energy stress under cold temperatures, Japanese cypress canopies exhibit a reversible color change associated with several photoprotective mechanisms known as “winter leaf reddening.” Here, several vegetation indices (VIs), including the photochemical reflectance index (PRI), rhodoxanthin index (RI), chlorophyll/carotenoid ratio index (CCI), triangular PRI index (tri-PRI), and red-green vegetation index (RGVI) were utilized to track the influence of winter leaf reddening and photoprotection on canopy-scale light-use efficiency (LUE) determined by the eddy covariance technique. Seasonal changes in VIs, environmental factors, and LUE in Japanese cypress canopies between 2017 and 2021 indicated that VIs could detect the phenology and LUE changes during winter leaf reddening. Our results suggest that winter leaf reddening occurrence is driven by prolonged low temperatures, and accompanied by dynamic xanthophyll cycle suppression, rhodoxanthin accumulation, and LUE reduction. Once stressful conditions are released, rhodoxanthin quickly decomposes and the remaining xanthophyll pigment may lead the canopy reddish-brown to persist longer. The integration of remote sensing and eddy covariance methods facilitates the validation of traditional results observed at the leaf scale within the context of the canopy scale, offering insights into how vegetation adjusts photosynthesis in response to environment stress.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"363 ","pages":"Article 110427"},"PeriodicalIF":5.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071578","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}
Pub Date : 2025-01-31DOI: 10.1016/j.agrformet.2025.110424
Alexandra Koller , Matthias Kunz , Maria D. Perles-Garcia , Goddert von Oheimb
Stand structural complexity influences various forest ecosystem functions, such as carbon storage or productivity. However, defining and measuring stand structural complexity is not trivial, as different structural attributes can be used to describe stand structure. We focus on a terrestrial laser scan-based stand structural complexity index (SSCI) and its components, mean fractal dimension (MeanFrac) and effective number of layers (ENL). These indices are now widely used, but there is still a lack of understanding of what exactly constitutes them. In this study, we analysed which structural attributes of individual trees determine these indices at which spatial scale. For our analysis, we used a high-resolution terrestrial laser scanning (TLS) dataset consisting of 11 structural attributes of over 1300 individual trees from 30 study plots of a young tree experiment in subtropical China. Our results show that averaged values of structural attributes of individual trees outperform values describing variation. Therefore, we suggest that SSCI, MeanFrac, and ENL depend on the magnitude rather than the variation of structural attributes among trees in a stand. We also found that SSCI is mainly determined by inner, i.e. branching intensity and branch number, and outer crown structure, i.e. crown compactness. MeanFrac is best described by branching intensity. Thus, a higher canopy space filling, i.e. higher density, leads to a higher stand structural complexity. Tree height and diameter at breast height are the main determinants of ENL. For the spatial scales we selected, only MeanFrac proved to be sensitive. The path analysis showed that different structural attributes (branching intensity vs. tree height) promote different aspects of stand structural complexity (horizontal vs. vertical), providing a variety of management options to increase stand structural complexity. Our results show that to better understand stand structural complexity, it is essential to include crown structural attributes in the assessment of stand structure.
{"title":"3D structural complexity of forest stands is determined by the magnitude of inner and outer crown structural attributes of individual trees","authors":"Alexandra Koller , Matthias Kunz , Maria D. Perles-Garcia , Goddert von Oheimb","doi":"10.1016/j.agrformet.2025.110424","DOIUrl":"10.1016/j.agrformet.2025.110424","url":null,"abstract":"<div><div>Stand structural complexity influences various forest ecosystem functions, such as carbon storage or productivity. However, defining and measuring stand structural complexity is not trivial, as different structural attributes can be used to describe stand structure. We focus on a terrestrial laser scan-based stand structural complexity index (SSCI) and its components, mean fractal dimension (MeanFrac) and effective number of layers (ENL). These indices are now widely used, but there is still a lack of understanding of what exactly constitutes them. In this study, we analysed which structural attributes of individual trees determine these indices at which spatial scale. For our analysis, we used a high-resolution terrestrial laser scanning (TLS) dataset consisting of 11 structural attributes of over 1300 individual trees from 30 study plots of a young tree experiment in subtropical China. Our results show that averaged values of structural attributes of individual trees outperform values describing variation. Therefore, we suggest that SSCI, MeanFrac, and ENL depend on the magnitude rather than the variation of structural attributes among trees in a stand. We also found that SSCI is mainly determined by inner, i.e. branching intensity and branch number, and outer crown structure, i.e. crown compactness. MeanFrac is best described by branching intensity. Thus, a higher canopy space filling, i.e. higher density, leads to a higher stand structural complexity. Tree height and diameter at breast height are the main determinants of ENL. For the spatial scales we selected, only MeanFrac proved to be sensitive. The path analysis showed that different structural attributes (branching intensity vs. tree height) promote different aspects of stand structural complexity (horizontal vs. vertical), providing a variety of management options to increase stand structural complexity. Our results show that to better understand stand structural complexity, it is essential to include crown structural attributes in the assessment of stand structure.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"363 ","pages":"Article 110424"},"PeriodicalIF":5.6,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143072238","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}
Pub Date : 2025-01-30DOI: 10.1016/j.agrformet.2025.110423
Shanshan Yang , Jiahua Zhang , Jiaqi Han , Yun Bai , Lan Xun , Sha Zhang , Dan Cao , Jingwen Wang
Water use efficiency (WUE) is an important metric for quantifying the trade-off between ecosystem photosynthesis and transpiration, which can reflect how ecosystems respond to extreme climate events (e.g., drought). However, due to the different definitions of WUE indices and the complexity of drought with different dimensions, the responses of ecosystem WUE to drought still remain debated. Here, we use global flux observations to comprehensively examine whether different WUE indices (i.e., WUET=GPP/T, WUEET=GPP/ET, and uWUE= GPP*VPD0.5/ET) have consistent responses to drought and how their responses are affected by drought intensity, duration and timing. The results show that WUET decreases, WUEET changes inapparently in direction of positive or negative, and uWUE increases during drought, although they have the same component GPP/T. The drought responses of ecosystem WUEs are significantly and nonlinearly influenced by drought intensity and duration, but insignificantly by drought timing. Increase in drought intensity leads to a higher reduction in WUET but greater increase in WUEET and uWUE. Short-term (< 2 months) and long-term droughts (> 6 months) have similar negative effects on WUET and WUEET, while medium to long-term droughts exert great positive impact on uWUE. The influences of drought intensity and duration are varied with drought timing. Further driver analyses reveal the unchanged GPP and increased T jointly lead to the decline in WUET during drought. Meanwhile, drought-driven rises in T/ET and VPD offset the reduced GPP/T, resulting in the inapparent change of WUEET and increase of uWUE, respectively. Overall, WUET response to drought is determined by T, while both WUEET and uWUE are controlled by T/ET. Our study highlights the necessary of disentangling the drought responses of different WUE indices with considering different drought dimensions, and investigating the T/ET variability during drought will provide deeper physiological understanding of ecosystem carbon-water coupling during drought.
{"title":"The ratio of transpiration to evapotranspiration dominates ecosystem water use efficiency response to drought","authors":"Shanshan Yang , Jiahua Zhang , Jiaqi Han , Yun Bai , Lan Xun , Sha Zhang , Dan Cao , Jingwen Wang","doi":"10.1016/j.agrformet.2025.110423","DOIUrl":"10.1016/j.agrformet.2025.110423","url":null,"abstract":"<div><div>Water use efficiency (WUE) is an important metric for quantifying the trade-off between ecosystem photosynthesis and transpiration, which can reflect how ecosystems respond to extreme climate events (e.g., drought). However, due to the different definitions of WUE indices and the complexity of drought with different dimensions, the responses of ecosystem WUE to drought still remain debated. Here, we use global flux observations to comprehensively examine whether different WUE indices (i.e., WUE<sub>T</sub>=GPP/T, WUE<sub>ET</sub>=GPP/ET, and uWUE= GPP*VPD<sup>0.5</sup>/ET) have consistent responses to drought and how their responses are affected by drought intensity, duration and timing. The results show that WUE<sub>T</sub> decreases, WUE<sub>ET</sub> changes inapparently in direction of positive or negative, and uWUE increases during drought, although they have the same component GPP/T. The drought responses of ecosystem WUEs are significantly and nonlinearly influenced by drought intensity and duration, but insignificantly by drought timing. Increase in drought intensity leads to a higher reduction in WUE<sub>T</sub> but greater increase in WUE<sub>ET</sub> and uWUE. Short-term (< 2 months) and long-term droughts (> 6 months) have similar negative effects on WUE<sub>T</sub> and WUE<sub>ET</sub>, while medium to long-term droughts exert great positive impact on uWUE. The influences of drought intensity and duration are varied with drought timing. Further driver analyses reveal the unchanged GPP and increased T jointly lead to the decline in WUE<sub>T</sub> during drought. Meanwhile, drought-driven rises in T/ET and VPD offset the reduced GPP/T, resulting in the inapparent change of WUE<sub>ET</sub> and increase of uWUE, respectively. Overall, WUE<sub>T</sub> response to drought is determined by T, while both WUE<sub>ET</sub> and uWUE are controlled by T/ET. Our study highlights the necessary of disentangling the drought responses of different WUE indices with considering different drought dimensions, and investigating the T/ET variability during drought will provide deeper physiological understanding of ecosystem carbon-water coupling during drought.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"363 ","pages":"Article 110423"},"PeriodicalIF":5.6,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143056796","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}
Pub Date : 2025-01-30DOI: 10.1016/j.agrformet.2025.110428
Shuping Du , Shanhu Jiang , Liliang Ren , Yongwei Zhu , Hao Cui , Miao He , Chong-Yu Xu
Root zone storage capacity (Sr) represents the maximum subsurface storage accessible to plant roots. It is primarily influenced by water availability and water demand, thus exhibiting temporal change in response to climate variations. Previous studies have primarily focused on the spatial patterns of Sr across local to global scales; however, there remains a limited understanding of its temporal patterns, particularly in relation to seasonal changes. This work explores the seasonal behavior of Sr for wet and dry seasons and the hydrological regulation of seasonal Sr. We propose a seasonal modeling framework based on apportionment entropy, which considers the phase difference between water and energy. Within this framework, the PDM-FLEX hydrological model, an integration of the probability distributed model (PDM) with the FLEX lumped model, was employed to calculate catchment-scale Sr for each season across 671 catchments in the contiguous United States. Results show that: i) this framework can effectively capture seasonal Sr, with wet season Sr (an average of 564 mm) generally being smaller than dry season Sr (an average of 820 mm) for most catchments. In the west, plants routinely access deep water, leading to comparable Sr for both wet and dry seasons. Incorporating seasonal Sr into the hydrological model can improve simulation performance across time scales; ii) dry season Sr is more responsive to hydroclimatic control compared to wet season Sr, as plants in arid climates are more sensitive to water accessibility; and iii) during the wet season, low Sr relative to precipitation leads to an unresponsive hydrological reaction. However, during the dry season, a routine correlation between Sr and precipitation produces responsive hydrological behavior. These findings indicate that plants seasonally adapt their root systems and that these seasonal variations in Sr would have significant hydrological implications.
{"title":"Seasonal patterns and hydrological regulations of root zone storage capacity across United States","authors":"Shuping Du , Shanhu Jiang , Liliang Ren , Yongwei Zhu , Hao Cui , Miao He , Chong-Yu Xu","doi":"10.1016/j.agrformet.2025.110428","DOIUrl":"10.1016/j.agrformet.2025.110428","url":null,"abstract":"<div><div>Root zone storage capacity (S<sub>r</sub>) represents the maximum subsurface storage accessible to plant roots. It is primarily influenced by water availability and water demand, thus exhibiting temporal change in response to climate variations. Previous studies have primarily focused on the spatial patterns of S<sub>r</sub> across local to global scales; however, there remains a limited understanding of its temporal patterns, particularly in relation to seasonal changes. This work explores the seasonal behavior of S<sub>r</sub> for wet and dry seasons and the hydrological regulation of seasonal S<sub>r</sub>. We propose a seasonal modeling framework based on apportionment entropy, which considers the phase difference between water and energy. Within this framework, the PDM-FLEX hydrological model, an integration of the probability distributed model (PDM) with the FLEX lumped model, was employed to calculate catchment-scale S<sub>r</sub> for each season across 671 catchments in the contiguous United States. Results show that: i) this framework can effectively capture seasonal S<sub>r</sub>, with wet season S<sub>r</sub> (an average of 564 mm) generally being smaller than dry season S<sub>r</sub> (an average of 820 mm) for most catchments. In the west, plants routinely access deep water, leading to comparable S<sub>r</sub> for both wet and dry seasons. Incorporating seasonal S<sub>r</sub> into the hydrological model can improve simulation performance across time scales; ii) dry season S<sub>r</sub> is more responsive to hydroclimatic control compared to wet season S<sub>r</sub>, as plants in arid climates are more sensitive to water accessibility; and iii) during the wet season, low S<sub>r</sub> relative to precipitation leads to an unresponsive hydrological reaction. However, during the dry season, a routine correlation between S<sub>r</sub> and precipitation produces responsive hydrological behavior. These findings indicate that plants seasonally adapt their root systems and that these seasonal variations in S<sub>r</sub> would have significant hydrological implications.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"363 ","pages":"Article 110428"},"PeriodicalIF":5.6,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143056797","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}
Integrating chemical fertilizers and organic manures is critical for improving soil health, increasing crop production, and mitigating the adverse environmental effects of the rice-wheat cropping system (RWCS). Numerous attempts have been made to evaluate the influence of integrated nutrient management (INM) on both crop yields and greenhouse gas (GHG) emissions during a single crop growing season. However, few studies have quantified the impact across an entire rotation cycle in this cropping system, considering the CO2 uptake due to soil carbon (C) sequestration and saving of chemical fertilizer in INM practices. Therefore, the study was conducted to quantify the effects of 38 years of INM in rice-wheat cropping system on C sequestration and GHG emissions. Five treatment combinations of fertilizer nutrients (NPK) alone and their partial substitution (25 % N) with organic sources either through farmyard manure (FYM) or wheat cut straw (WCS) or green manuring (GM) in rice, and only chemical fertilizers at different levels in succeeding wheat crop were studied for two years (2019–20 and 2020–21). The results showed that substituting 25 % fertilizer N with organic materials (FYM/WCS/GM) in rice and using 25 % less NPK in wheat for 38 years significantly improved soil properties, including SOC sequestration, and increased crop yield (except WCS). INM increased the GHG emissions over chemical fertilization (100 % NPK), but the GHGI (greenhouse gas intensity) was equivalent, except for the usage of WCS in RWCS. Overall, in RWCS, INM via substituting 25 % fertilizer N with FYM/GM in rice and applying 75 % NPK in wheat had lower GHGI than only chemical fertilizer application, indicating the advantages of these amendments for increasing soil health, crop production, and climate change mitigation. Further research is required to determine the correlation between the mineralization patterns of added organic amendments, soil C fractions during critical crop growth stages, and GHG emissions.
{"title":"Impact of 38-year integrated nutrient management on soil carbon sequestration and greenhouse gas emissions of a rice-wheat cropping system","authors":"Manjeet Kaur , G.S. Dheri , S.S. Walia , O.P. Choudhary","doi":"10.1016/j.agrformet.2025.110415","DOIUrl":"10.1016/j.agrformet.2025.110415","url":null,"abstract":"<div><div>Integrating chemical fertilizers and organic manures is critical for improving soil health, increasing crop production, and mitigating the adverse environmental effects of the rice-wheat cropping system (RWCS). Numerous attempts have been made to evaluate the influence of integrated nutrient management (INM) on both crop yields and greenhouse gas (GHG) emissions during a single crop growing season. However, few studies have quantified the impact across an entire rotation cycle in this cropping system, considering the CO<sub>2</sub> uptake due to soil carbon (C) sequestration and saving of chemical fertilizer in INM practices. Therefore, the study was conducted to quantify the effects of 38 years of INM in rice-wheat cropping system on C sequestration and GHG emissions. Five treatment combinations of fertilizer nutrients (NPK) alone and their partial substitution (25 % N) with organic sources either through farmyard manure (FYM) or wheat cut straw (WCS) or green manuring (GM) in rice, and only chemical fertilizers at different levels in succeeding wheat crop were studied for two years (2019–20 and 2020–21). The results showed that substituting 25 % fertilizer N with organic materials (FYM/WCS/GM) in rice and using 25 % less NPK in wheat for 38 years significantly improved soil properties, including SOC sequestration, and increased crop yield (except WCS). INM increased the GHG emissions over chemical fertilization (100 % NPK), but the GHGI (greenhouse gas intensity) was equivalent, except for the usage of WCS in RWCS. Overall, in RWCS, INM via substituting 25 % fertilizer N with FYM/GM in rice and applying 75 % NPK in wheat had lower GHGI than only chemical fertilizer application, indicating the advantages of these amendments for increasing soil health, crop production, and climate change mitigation. Further research is required to determine the correlation between the mineralization patterns of added organic amendments, soil C fractions during critical crop growth stages, and GHG emissions.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"363 ","pages":"Article 110415"},"PeriodicalIF":5.6,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143057189","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}
Understanding how epiphytic vascular plants respond to drought is essential for elucidating the potential mechanisms that may contribute to their resilience in the context of global climate change. Despite numerous studies have estimated tropical epiphytic vascular plants’ water source and use efficiency, their response to drought induced water scarcity poorly understood. We conducted an in-situ water reduction control experiment (i.e., controlling rain and fog water, each with three treatments) on epiphytic vascular plant communities in a biodiverse hotspots region of Hainan tropical cloud forest. We then investigated the water sources and water use efficiency (WUE) of epiphytic vascular plants under different drought gradients. We found a significant seasonal variation in water sources: 63 %–67 % in the dry season (November to April of the next year) and 64 %–70 % in the wet season (May to October) came from fog and rain, respectively In the wet season, epiphytic ferns utilized 39 % fog and 61 % rain, while orchids utilized 31 % fog and 69 % rain. Ferns absorbed significantly more fog water than orchids under all drought gradients. In the dry season, 63 % of the water in epiphytic ferns and 64 % in orchids originated from fog, while 37 % and 36 % from rain for ephiphytic ferns and orchids respectively. The WUE of ferns was significantly higher than that of orchids under all drought gradients. These findings reveal that both epiphytic vascular plant communities and epiphytic taxa display selective and complementary water uptake strategies, with distinct differences in water use strategy between epiphytic ferns and orchids.
{"title":"Drought-induced water use patterns in epiphytic ferns and orchids of the Hainan tropical cloud forest, South China","authors":"Liangyu Wen , Dexu Zhang , Chuchu Xiao , Guang Feng , Ewuketu Linger , Wenxing Long","doi":"10.1016/j.agrformet.2025.110400","DOIUrl":"10.1016/j.agrformet.2025.110400","url":null,"abstract":"<div><div>Understanding how epiphytic vascular plants respond to drought is essential for elucidating the potential mechanisms that may contribute to their resilience in the context of global climate change. Despite numerous studies have estimated tropical epiphytic vascular plants’ water source and use efficiency, their response to drought induced water scarcity poorly understood. We conducted an <em>in-situ</em> water reduction control experiment (<em>i.e.,</em> controlling rain and fog water, each with three treatments) on epiphytic vascular plant communities in a biodiverse hotspots region of Hainan tropical cloud forest. We then investigated the water sources and water use efficiency (WUE) of epiphytic vascular plants under different drought gradients. We found a significant seasonal variation in water sources: 63 %–67 % in the dry season (November to April of the next year) and 64 %–70 % in the wet season (May to October) came from fog and rain, respectively In the wet season, epiphytic ferns utilized 39 % fog and 61 % rain, while orchids utilized 31 % fog and 69 % rain. Ferns absorbed significantly more fog water than orchids under all drought gradients. In the dry season, 63 % of the water in epiphytic ferns and 64 % in orchids originated from fog, while 37 % and 36 % from rain for ephiphytic ferns and orchids respectively. The WUE of ferns was significantly higher than that of orchids under all drought gradients. These findings reveal that both epiphytic vascular plant communities and epiphytic taxa display selective and complementary water uptake strategies, with distinct differences in water use strategy between epiphytic ferns and orchids.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"363 ","pages":"Article 110400"},"PeriodicalIF":5.6,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143056791","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}
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