It is well known that aboveground productivity usually increases with precipitation. However, how belowground carbon (C) processes respond to changes in precipitation remains elusive, although belowground net primary productivity (BNPP) represents more than one-half of NPP and soil stores the largest terrestrial C in the biosphere. This study is to review response patterns of belowground C processes (BNPP and soil C) to changes in precipitation from transect studies, manipulative experiments, modeling, and data integration and synthesis. The results suggest the possible existence of nonlinear patterns of BNPP and soil C in response to changes in precipitation, which is largely different from linear response for aboveground productivity. C allocation, root turnover time, and species composition may be three key processes underlying mechanisms of the nonlinear responses to changes in precipitation for belowground C processes. In addition, microbial community structure and long-term ecosystem processes (e.g., mineral assemblage, soil texture, aggregate stability) may also affect response pattern of belowground C processes to changes in precipitation. At last, we discuss implications and future perspectives for potential nonlinear responses of belowground C processes to changes in precipitation.
{"title":"Patterns and mechanisms of belowground carbon responses to changes in precipitation","authors":"Hongyang Chen, Qi Zhang, Lingyan Zhou, Xuhui Zhou","doi":"10.1093/jpe/rtae011","DOIUrl":"https://doi.org/10.1093/jpe/rtae011","url":null,"abstract":"\u0000 It is well known that aboveground productivity usually increases with precipitation. However, how belowground carbon (C) processes respond to changes in precipitation remains elusive, although belowground net primary productivity (BNPP) represents more than one-half of NPP and soil stores the largest terrestrial C in the biosphere. This study is to review response patterns of belowground C processes (BNPP and soil C) to changes in precipitation from transect studies, manipulative experiments, modeling, and data integration and synthesis. The results suggest the possible existence of nonlinear patterns of BNPP and soil C in response to changes in precipitation, which is largely different from linear response for aboveground productivity. C allocation, root turnover time, and species composition may be three key processes underlying mechanisms of the nonlinear responses to changes in precipitation for belowground C processes. In addition, microbial community structure and long-term ecosystem processes (e.g., mineral assemblage, soil texture, aggregate stability) may also affect response pattern of belowground C processes to changes in precipitation. At last, we discuss implications and future perspectives for potential nonlinear responses of belowground C processes to changes in precipitation.","PeriodicalId":503671,"journal":{"name":"Journal of Plant Ecology","volume":"119 25","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140089449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The tree height–diameter at breast height (H–DBH) and crown radius–DBH (CR–DBH) relationships are key for forest carbon/biomass estimation, parameterization in vegetation models and vegetation–atmosphere interactions. Although the H–DBH relationship has been widely investigated on site or regional scales, and a small amount of studies have involved CR–DBH relationships based on plot-level data, few studies have quantitatively verified the universality of these two relationships on a global scale. Accordingly, this study first evaluated the ability of 29 functions to fit the H–DBH and CR–DBH relationships for six different plant functional types (PFTs) on a global scale, based on a global plant trait database. Results showed that most functions were able to capture the H–DBH relationship for tropical PFTs and boreal needleleaf trees relatively accurately, but slightly less so for temperate PFTs and boreal broadleaf trees. For boreal PFTs, the S-shaped Logistic function fitted the H–DBH relationship best, while for temperate PFTs the Chapman–Richards function performed well. For tropical needleleaf trees, the fractional function of DBH could satisfactorily capture the H–DBH relationship, while for tropical broadleaf trees, the Weibull function and a composite function of fractions were the best choices. For CR–DBH, the fitting capabilities of all the functions were comparable for all PFTs except boreal broadleaf trees. The Logistic function performed best for two boreal PFTs and temperate broadleaf trees, but for temperate needleleaf trees and two tropical PFTs, some exponential functions demonstrated higher skill. This work provides a valuable foundation for parameterization improvements in vegetation models, and some clues to forest field investigations.
{"title":"Parameterization of Height–Diameter and Crown Radius–Diameter Relationships Across the Globe","authors":"Xiang Song, Jinxu Li, Xiaodong Zeng","doi":"10.1093/jpe/rtae005","DOIUrl":"https://doi.org/10.1093/jpe/rtae005","url":null,"abstract":"\u0000 The tree height–diameter at breast height (H–DBH) and crown radius–DBH (CR–DBH) relationships are key for forest carbon/biomass estimation, parameterization in vegetation models and vegetation–atmosphere interactions. Although the H–DBH relationship has been widely investigated on site or regional scales, and a small amount of studies have involved CR–DBH relationships based on plot-level data, few studies have quantitatively verified the universality of these two relationships on a global scale. Accordingly, this study first evaluated the ability of 29 functions to fit the H–DBH and CR–DBH relationships for six different plant functional types (PFTs) on a global scale, based on a global plant trait database. Results showed that most functions were able to capture the H–DBH relationship for tropical PFTs and boreal needleleaf trees relatively accurately, but slightly less so for temperate PFTs and boreal broadleaf trees. For boreal PFTs, the S-shaped Logistic function fitted the H–DBH relationship best, while for temperate PFTs the Chapman–Richards function performed well. For tropical needleleaf trees, the fractional function of DBH could satisfactorily capture the H–DBH relationship, while for tropical broadleaf trees, the Weibull function and a composite function of fractions were the best choices. For CR–DBH, the fitting capabilities of all the functions were comparable for all PFTs except boreal broadleaf trees. The Logistic function performed best for two boreal PFTs and temperate broadleaf trees, but for temperate needleleaf trees and two tropical PFTs, some exponential functions demonstrated higher skill. This work provides a valuable foundation for parameterization improvements in vegetation models, and some clues to forest field investigations.","PeriodicalId":503671,"journal":{"name":"Journal of Plant Ecology","volume":"1 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139829657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The tree height–diameter at breast height (H–DBH) and crown radius–DBH (CR–DBH) relationships are key for forest carbon/biomass estimation, parameterization in vegetation models and vegetation–atmosphere interactions. Although the H–DBH relationship has been widely investigated on site or regional scales, and a small amount of studies have involved CR–DBH relationships based on plot-level data, few studies have quantitatively verified the universality of these two relationships on a global scale. Accordingly, this study first evaluated the ability of 29 functions to fit the H–DBH and CR–DBH relationships for six different plant functional types (PFTs) on a global scale, based on a global plant trait database. Results showed that most functions were able to capture the H–DBH relationship for tropical PFTs and boreal needleleaf trees relatively accurately, but slightly less so for temperate PFTs and boreal broadleaf trees. For boreal PFTs, the S-shaped Logistic function fitted the H–DBH relationship best, while for temperate PFTs the Chapman–Richards function performed well. For tropical needleleaf trees, the fractional function of DBH could satisfactorily capture the H–DBH relationship, while for tropical broadleaf trees, the Weibull function and a composite function of fractions were the best choices. For CR–DBH, the fitting capabilities of all the functions were comparable for all PFTs except boreal broadleaf trees. The Logistic function performed best for two boreal PFTs and temperate broadleaf trees, but for temperate needleleaf trees and two tropical PFTs, some exponential functions demonstrated higher skill. This work provides a valuable foundation for parameterization improvements in vegetation models, and some clues to forest field investigations.
{"title":"Parameterization of Height–Diameter and Crown Radius–Diameter Relationships Across the Globe","authors":"Xiang Song, Jinxu Li, Xiaodong Zeng","doi":"10.1093/jpe/rtae005","DOIUrl":"https://doi.org/10.1093/jpe/rtae005","url":null,"abstract":"\u0000 The tree height–diameter at breast height (H–DBH) and crown radius–DBH (CR–DBH) relationships are key for forest carbon/biomass estimation, parameterization in vegetation models and vegetation–atmosphere interactions. Although the H–DBH relationship has been widely investigated on site or regional scales, and a small amount of studies have involved CR–DBH relationships based on plot-level data, few studies have quantitatively verified the universality of these two relationships on a global scale. Accordingly, this study first evaluated the ability of 29 functions to fit the H–DBH and CR–DBH relationships for six different plant functional types (PFTs) on a global scale, based on a global plant trait database. Results showed that most functions were able to capture the H–DBH relationship for tropical PFTs and boreal needleleaf trees relatively accurately, but slightly less so for temperate PFTs and boreal broadleaf trees. For boreal PFTs, the S-shaped Logistic function fitted the H–DBH relationship best, while for temperate PFTs the Chapman–Richards function performed well. For tropical needleleaf trees, the fractional function of DBH could satisfactorily capture the H–DBH relationship, while for tropical broadleaf trees, the Weibull function and a composite function of fractions were the best choices. For CR–DBH, the fitting capabilities of all the functions were comparable for all PFTs except boreal broadleaf trees. The Logistic function performed best for two boreal PFTs and temperate broadleaf trees, but for temperate needleleaf trees and two tropical PFTs, some exponential functions demonstrated higher skill. This work provides a valuable foundation for parameterization improvements in vegetation models, and some clues to forest field investigations.","PeriodicalId":503671,"journal":{"name":"Journal of Plant Ecology","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139889600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Phenological research is engaged in monitoring the influence of climate change on the natural environment. The International Phenological Gardens (IPG) network provides a valuable dataset of standardised tree phenology records dating back to the mid-20th century. To make best use of this actively growing record, it is important to investigate how network data can be applied to predict the timing of phenological events in natural populations. This study compared clonally propagated IPG downy birch (Betula pubescens Ehrh.) and hazel (Corylus avellana L.) specimens of central European provenance to nearby wild populations at the western-most margin of the IPG network, in the south-west of Ireland. In addition to monitoring by trained scientists, observations by citizen scientists were included. The order of the timing of phenological events among sites was consistent across two years, confirming reproducibility of the results. IPG trees had the earliest B. pubescens leaf unfolding and C. avellana flowering dates of the sites studied. In addition, leaf unfolding occurred later in the wild populations than expected from the temperature responses of the B. pubescens and C. avellana IPG clones. Natural variation in phenology also exceeded the historical change observed at the IPG site, suggesting a potential genetic basis for climate adaptation. Trunk circumference, reflecting the age-dependent increase in tree size, was found to influence C. avellana phenology, with earlier timing of phenological events in larger trees. This highlights tree size as an important consideration in the management of phenological gardens and tree phenology research in general.
物候学研究致力于监测气候变化对自然环境的影响。国际物候花园（IPG）网络提供了一个宝贵的标准化树木物候记录数据集，可追溯到 20 世纪中期。为了充分利用这一积极发展的记录，研究如何将网络数据用于预测自然种群中物候事件的时间非常重要。这项研究将中欧来源的 IPG 绒毛桦树（Betula pubescens Ehrh.）和榛树（Corylus avellana L.）克隆繁殖标本与 IPG 网络最西端（爱尔兰西南部）附近的野生种群进行了比较。除了训练有素的科学家进行监测外，还包括公民科学家的观察。不同地点的物候事件发生时间顺序在两年中保持一致，证实了结果的可重复性。在所研究的地点中，IPG 树的 B. pubescens 展叶和 C. avellana 开花的时间最早。此外，野生种群的展叶期晚于 B. pubescens 和 C. avellana IPG 克隆的温度反应。物候的自然变化也超过了在 IPG 地点观察到的历史变化，这表明气候适应有潜在的遗传基础。研究发现，树干周长反映了树体大小随年龄增长的变化，它影响了 C. avellana 的物候期，大树的物候期较早。这突出表明，在物候园管理和一般树木物候研究中，树木大小是一个重要的考虑因素。
{"title":"Comparison of the timing of spring phenological events between phenological garden trees and wild populations","authors":"Calum J Sweeney, Fidelma Butler, Astrid Wingler","doi":"10.1093/jpe/rtae008","DOIUrl":"https://doi.org/10.1093/jpe/rtae008","url":null,"abstract":"\u0000 Phenological research is engaged in monitoring the influence of climate change on the natural environment. The International Phenological Gardens (IPG) network provides a valuable dataset of standardised tree phenology records dating back to the mid-20th century. To make best use of this actively growing record, it is important to investigate how network data can be applied to predict the timing of phenological events in natural populations. This study compared clonally propagated IPG downy birch (Betula pubescens Ehrh.) and hazel (Corylus avellana L.) specimens of central European provenance to nearby wild populations at the western-most margin of the IPG network, in the south-west of Ireland. In addition to monitoring by trained scientists, observations by citizen scientists were included. The order of the timing of phenological events among sites was consistent across two years, confirming reproducibility of the results. IPG trees had the earliest B. pubescens leaf unfolding and C. avellana flowering dates of the sites studied. In addition, leaf unfolding occurred later in the wild populations than expected from the temperature responses of the B. pubescens and C. avellana IPG clones. Natural variation in phenology also exceeded the historical change observed at the IPG site, suggesting a potential genetic basis for climate adaptation. Trunk circumference, reflecting the age-dependent increase in tree size, was found to influence C. avellana phenology, with earlier timing of phenological events in larger trees. This highlights tree size as an important consideration in the management of phenological gardens and tree phenology research in general.","PeriodicalId":503671,"journal":{"name":"Journal of Plant Ecology","volume":"27 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139871444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Phenological research is engaged in monitoring the influence of climate change on the natural environment. The International Phenological Gardens (IPG) network provides a valuable dataset of standardised tree phenology records dating back to the mid-20th century. To make best use of this actively growing record, it is important to investigate how network data can be applied to predict the timing of phenological events in natural populations. This study compared clonally propagated IPG downy birch (Betula pubescens Ehrh.) and hazel (Corylus avellana L.) specimens of central European provenance to nearby wild populations at the western-most margin of the IPG network, in the south-west of Ireland. In addition to monitoring by trained scientists, observations by citizen scientists were included. The order of the timing of phenological events among sites was consistent across two years, confirming reproducibility of the results. IPG trees had the earliest B. pubescens leaf unfolding and C. avellana flowering dates of the sites studied. In addition, leaf unfolding occurred later in the wild populations than expected from the temperature responses of the B. pubescens and C. avellana IPG clones. Natural variation in phenology also exceeded the historical change observed at the IPG site, suggesting a potential genetic basis for climate adaptation. Trunk circumference, reflecting the age-dependent increase in tree size, was found to influence C. avellana phenology, with earlier timing of phenological events in larger trees. This highlights tree size as an important consideration in the management of phenological gardens and tree phenology research in general.
物候学研究致力于监测气候变化对自然环境的影响。国际物候花园（IPG）网络提供了一个宝贵的标准化树木物候记录数据集，可追溯到 20 世纪中期。为了充分利用这一积极发展的记录，研究如何将网络数据用于预测自然种群中物候事件的时间非常重要。这项研究将中欧来源的 IPG 绒毛桦树（Betula pubescens Ehrh.）和榛树（Corylus avellana L.）克隆繁殖标本与 IPG 网络最西端（爱尔兰西南部）附近的野生种群进行了比较。除了训练有素的科学家进行监测外，还包括公民科学家的观测。不同地点的物候事件发生时间顺序在两年中保持一致，证实了结果的可重复性。在所研究的地点中，IPG 树的 B. pubescens 展叶和 C. avellana 开花的时间最早。此外，野生种群的展叶期晚于 B. pubescens 和 C. avellana IPG 克隆的温度反应。物候的自然变化也超过了在 IPG 地点观察到的历史变化，这表明气候适应有潜在的遗传基础。研究发现，树干周长反映了树体大小随年龄增长的变化，它影响了 C. avellana 的物候期，大树的物候期较早。这突出表明，在物候园管理和一般树木物候研究中，树木大小是一个重要的考虑因素。
{"title":"Comparison of the timing of spring phenological events between phenological garden trees and wild populations","authors":"Calum J Sweeney, Fidelma Butler, Astrid Wingler","doi":"10.1093/jpe/rtae008","DOIUrl":"https://doi.org/10.1093/jpe/rtae008","url":null,"abstract":"\u0000 Phenological research is engaged in monitoring the influence of climate change on the natural environment. The International Phenological Gardens (IPG) network provides a valuable dataset of standardised tree phenology records dating back to the mid-20th century. To make best use of this actively growing record, it is important to investigate how network data can be applied to predict the timing of phenological events in natural populations. This study compared clonally propagated IPG downy birch (Betula pubescens Ehrh.) and hazel (Corylus avellana L.) specimens of central European provenance to nearby wild populations at the western-most margin of the IPG network, in the south-west of Ireland. In addition to monitoring by trained scientists, observations by citizen scientists were included. The order of the timing of phenological events among sites was consistent across two years, confirming reproducibility of the results. IPG trees had the earliest B. pubescens leaf unfolding and C. avellana flowering dates of the sites studied. In addition, leaf unfolding occurred later in the wild populations than expected from the temperature responses of the B. pubescens and C. avellana IPG clones. Natural variation in phenology also exceeded the historical change observed at the IPG site, suggesting a potential genetic basis for climate adaptation. Trunk circumference, reflecting the age-dependent increase in tree size, was found to influence C. avellana phenology, with earlier timing of phenological events in larger trees. This highlights tree size as an important consideration in the management of phenological gardens and tree phenology research in general.","PeriodicalId":503671,"journal":{"name":"Journal of Plant Ecology","volume":"25 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139811760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jing Zhu, Xuelian Wang, Xing Jin, Lan Jiang, Hong-Yu Lin, Yang Hu, Jin-fu Liu, Zhong-Sheng He
Variations in plant traits are indicative of plant adaptations to forest environments, and studying their relationships with tree growth provides valuable insights into forest regeneration. The spatial arrangement of plant seeds within the forest litter or soil critically influences the variations of root-leaf traits, thereby affecting the adaptive strategies of emerging seedlings. However, our current understanding of the impacts of individual root-leaf traits on seedling growth in different relative position, and whether these traits together affect growth, remains limited. This study focuses on the dominant tree species, Castanopsis kawakamii, within the Sanming C. kawakamii Nature Reserve of China. The present experiment aimed to examine the variations in root-leaf traits of seedling, focus on the relative positions of seeds within different layers: beneath or above the litter layer, or within the bare soil layer (without litter). Our findings contributed evidence supporting a coordinated relationship between root and leaf traits, wherein leaf traits vary in conjunction with root traits in the relative positions of seeds. Specifically, we observed that seedlings exhibited higher values for specific leaf area and average root diameter, while displaying lower root tissue density. The mixed model explained 86.1% of the variation in root-leaf traits, surpassing the variation explained by the relative positions. Furthermore, soil nitrogen acts as a mediator, regulating the relationship between seedling growth and root-leaf traits, specifically leaf dry matter content and root tissue density. Therefore, future studies should consider artificially manipulating tree species diversity based on root-leaf traits characteristics to promote forest recovery.
{"title":"Relative position of seeds driven the seedling growth are mediated by root - leaf traits","authors":"Jing Zhu, Xuelian Wang, Xing Jin, Lan Jiang, Hong-Yu Lin, Yang Hu, Jin-fu Liu, Zhong-Sheng He","doi":"10.1093/jpe/rtae004","DOIUrl":"https://doi.org/10.1093/jpe/rtae004","url":null,"abstract":"\u0000 Variations in plant traits are indicative of plant adaptations to forest environments, and studying their relationships with tree growth provides valuable insights into forest regeneration. The spatial arrangement of plant seeds within the forest litter or soil critically influences the variations of root-leaf traits, thereby affecting the adaptive strategies of emerging seedlings. However, our current understanding of the impacts of individual root-leaf traits on seedling growth in different relative position, and whether these traits together affect growth, remains limited. This study focuses on the dominant tree species, Castanopsis kawakamii, within the Sanming C. kawakamii Nature Reserve of China. The present experiment aimed to examine the variations in root-leaf traits of seedling, focus on the relative positions of seeds within different layers: beneath or above the litter layer, or within the bare soil layer (without litter). Our findings contributed evidence supporting a coordinated relationship between root and leaf traits, wherein leaf traits vary in conjunction with root traits in the relative positions of seeds. Specifically, we observed that seedlings exhibited higher values for specific leaf area and average root diameter, while displaying lower root tissue density. The mixed model explained 86.1% of the variation in root-leaf traits, surpassing the variation explained by the relative positions. Furthermore, soil nitrogen acts as a mediator, regulating the relationship between seedling growth and root-leaf traits, specifically leaf dry matter content and root tissue density. Therefore, future studies should consider artificially manipulating tree species diversity based on root-leaf traits characteristics to promote forest recovery.","PeriodicalId":503671,"journal":{"name":"Journal of Plant Ecology","volume":"3 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139438251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhao-yong Hu, Genxu Wang, Xiang-yang Sun, Kewei Huang, Chunlin Song, Yang Li, Shouqin Sun, Juying Sun, Shan Lin
Energy partitioning and evapotranspiration (ET) of alpine meadows in permafrost areas are crucial for the water cycle on the Qinghai-Tibet Plateau (QTP). However, seasonal (freeze-thaw cycle) variations in energy partitioning and ET and their driving factors must be clarified. Therefore, four-year energy fluxes (i.e., latent heat (LE) and sensible heat (H)) were observed, and bulk parameters (i.e., surface conductance, decoupling coefficient (Ω) and Priestley-Taylor coefficient (α)) were estimated in an alpine meadow in the hinterland of the QTP. Mean daily LE (27.45±23.89 W/m2) and H (32.51±16.72 W/m2) accounted for 31.71% and 50.14% of available energy, respectively. More of available energy was allocated to LE during the rainfall period, while 67.54±28.44% was allocated to H during the frozen period. H was half the LE during the rainfall period and seven times the LE during the frozen period due to low soil water content and vegetation coverage during the frozen season. Mean annual ET was 347.34±8.39 mm/year, close to the mean annual precipitation. Low mean daily Ω (0.45±0.23) and α (0.60±0.29) throughout the year suggested that ET in the alpine meadow was limited by water availability. However, ET was constrained by available energy because of sufficient water supply from precipitation during the rainfall season. In contrast, large differences between ET and precipitation indicated that soil water was supplied via lateral flow from melting upstream glaciers and snow during the transition season. The results suggest that seasonal variations in bulk parameters should be considered when simulating water and energy fluxes in permafrost regions.
永冻土区高山草甸的能量分配和蒸散（ET）对青藏高原的水循环至关重要。然而，必须明确能量分配和蒸散发的季节性（冻融循环）变化及其驱动因素。因此，在青藏高原腹地的高寒草甸上观测了四年的能量通量（即潜热（LE）和显热（H）），并估算了体积参数（即表面传导率、解耦系数（Ω）和普利斯特里-泰勒系数（α））。平均每天LE（27.45±23.89 W/m2）和H（32.51±16.72 W/m2）分别占可利用能量的31.71%和50.14%。在降雨期，更多的可利用能量被分配给 LE，而在冰冻期，67.54±28.44%的可利用能量被分配给 H。由于冰冻期土壤含水量和植被覆盖率较低，降雨期 H 为 LE 的一半，冰冻期为 LE 的 7 倍。年平均蒸散发为（347.34±8.39）毫米/年，接近年平均降水量。全年日平均Ω（0.45±0.23）和α（0.60±0.29）较低，表明高山草甸的蒸散发受到水供应的限制。然而，由于降雨季节降水量充足，蒸散发受到可用能量的限制。相反，蒸散发与降水量之间的巨大差异表明，在过渡季节，土壤水是通过上游冰川融化和积雪的侧向流动供应的。结果表明，在模拟永久冻土地区的水和能量通量时，应考虑体积参数的季节性变化。
{"title":"Energy partitioning and controlling factors of evapotranspiration in an alpine meadow in the permafrost region of the Qinghai-Tibet Plateau","authors":"Zhao-yong Hu, Genxu Wang, Xiang-yang Sun, Kewei Huang, Chunlin Song, Yang Li, Shouqin Sun, Juying Sun, Shan Lin","doi":"10.1093/jpe/rtae002","DOIUrl":"https://doi.org/10.1093/jpe/rtae002","url":null,"abstract":"\u0000 Energy partitioning and evapotranspiration (ET) of alpine meadows in permafrost areas are crucial for the water cycle on the Qinghai-Tibet Plateau (QTP). However, seasonal (freeze-thaw cycle) variations in energy partitioning and ET and their driving factors must be clarified. Therefore, four-year energy fluxes (i.e., latent heat (LE) and sensible heat (H)) were observed, and bulk parameters (i.e., surface conductance, decoupling coefficient (Ω) and Priestley-Taylor coefficient (α)) were estimated in an alpine meadow in the hinterland of the QTP. Mean daily LE (27.45±23.89 W/m2) and H (32.51±16.72 W/m2) accounted for 31.71% and 50.14% of available energy, respectively. More of available energy was allocated to LE during the rainfall period, while 67.54±28.44% was allocated to H during the frozen period. H was half the LE during the rainfall period and seven times the LE during the frozen period due to low soil water content and vegetation coverage during the frozen season. Mean annual ET was 347.34±8.39 mm/year, close to the mean annual precipitation. Low mean daily Ω (0.45±0.23) and α (0.60±0.29) throughout the year suggested that ET in the alpine meadow was limited by water availability. However, ET was constrained by available energy because of sufficient water supply from precipitation during the rainfall season. In contrast, large differences between ET and precipitation indicated that soil water was supplied via lateral flow from melting upstream glaciers and snow during the transition season. The results suggest that seasonal variations in bulk parameters should be considered when simulating water and energy fluxes in permafrost regions.","PeriodicalId":503671,"journal":{"name":"Journal of Plant Ecology","volume":"2 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139380472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Climate warming, rising atmospheric CO2 concentration (Ca) and nitrogen (N) availability are exerting profound impacts on global forest ecosystems, particularly in high-altitude mountains. This study investigated the tree-growth dynamics of timberline Larix chinensis in the Taibai Mountain, central China, to explore its ecophysiological responses to environmental stresses by combining tree growth and stable isotopes. The results indicated that the growth rate of L. chinensis has significantly increased since the 1960s, and that tree growth in this timberline was particularly sensitive to temperature in spring. Moreover, the continuously rising iWUE, linked to higher Ca and warmer environment, promoted the growth of L. chinensis. Before the 1960s, tree-ring δ15N gradually increased, then shifted to an insignificant decline with the acceleration of tree growth, and broke the pre-existing carbon-nitrogen balance. Meanwhile, climate warming and increased iWUE have replaced N as the principal drivers of tree growth since the 1960s. It is believed that L. chinensis may gradually suffer a decline in nitrogen availability as it continues to grow rapidly. The insightful understanding of the biochemical mechanisms of plant responses to growth-related environmental conditions will improve our ability to predict the evolution of high-elevation mountain ecosystems in the future.
{"title":"Weakened relationship between tree growth and nitrogen availability due to global CO2 increase and warming in the Taibai Mountain timberline, central China","authors":"Lelong Yin, Xiaohong Liu, Xiaomin Zeng, Ziyi Wang, Guobao Xu, Liangju Zhao, Qiangqiang Lu, Lingnan Zhang, Xiaoyu Xing","doi":"10.1093/jpe/rtae001","DOIUrl":"https://doi.org/10.1093/jpe/rtae001","url":null,"abstract":"\u0000 Climate warming, rising atmospheric CO2 concentration (Ca) and nitrogen (N) availability are exerting profound impacts on global forest ecosystems, particularly in high-altitude mountains. This study investigated the tree-growth dynamics of timberline Larix chinensis in the Taibai Mountain, central China, to explore its ecophysiological responses to environmental stresses by combining tree growth and stable isotopes. The results indicated that the growth rate of L. chinensis has significantly increased since the 1960s, and that tree growth in this timberline was particularly sensitive to temperature in spring. Moreover, the continuously rising iWUE, linked to higher Ca and warmer environment, promoted the growth of L. chinensis. Before the 1960s, tree-ring δ15N gradually increased, then shifted to an insignificant decline with the acceleration of tree growth, and broke the pre-existing carbon-nitrogen balance. Meanwhile, climate warming and increased iWUE have replaced N as the principal drivers of tree growth since the 1960s. It is believed that L. chinensis may gradually suffer a decline in nitrogen availability as it continues to grow rapidly. The insightful understanding of the biochemical mechanisms of plant responses to growth-related environmental conditions will improve our ability to predict the evolution of high-elevation mountain ecosystems in the future.","PeriodicalId":503671,"journal":{"name":"Journal of Plant Ecology","volume":"5 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139383906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuan Su, Shuaikai Wu, Jie Hao, Huajie Diao, Kuanhu Dong, Changhui Wang
Reabsorbing nutrients from senescent tissues before leaf falling has been recognized as a strategy to adapt to nutrient deficiency. However, how nutrient resorption modulates the nitrogen (N)–phosphorus (P) balance inside plants remains unclear, especially under increased soil N availability. We examined the impacts of N addition at varying rates (0–32 g N m−2 yr−1) on nutrient resorption and the performance of nutrient resorption on controlling the internal N–P balance in the leaf and stem of a dominant grass species, Leymus secalinus, in a saline-alkaline grassland in northern China. After 6 years of N addition, N concentration and N:P ratio in green and senesced tissues (leaf and stem) rose with increasing N addition. The P concentration in green tissues decreased, but did not significantly change in senesced tissues with increasing N addition. The N resorption efficiency (NRE), P resorption efficiency (PRE) and NRE:PRE ratio significantly decreased along the N addition gradient. Moreover, we found more sensitive responses of N:P ratio in senesced tissues than in green tissues; such exacerbation of plant internal N–P imbalances mainly resulted from a disproportionate reduction in nutrient resorption, especially NRE. Overall, our study suggested that differences in NRE and PRE further exacerbated the internal N–P imbalances in plant litters.
在落叶前从衰老组织中重新吸收养分被认为是适应养分缺乏的一种策略。然而，养分吸收如何调节植物体内的氮（N）-磷（P）平衡仍不清楚，尤其是在土壤氮供应量增加的情况下。我们研究了在中国北方盐碱地草地上以不同速率（0-32 g N m-2 yr-1）添加氮对养分吸收的影响，以及养分吸收对控制优势禾本科牧草（Leymus secalinus）叶片和茎内部氮磷平衡的作用。经过 6 年的氮添加，绿色组织和衰老组织（叶片和茎）中的氮浓度和氮磷比随着氮添加量的增加而上升。随着氮添加量的增加，绿色组织中的磷浓度下降，但衰老组织中的磷浓度变化不明显。氮吸收效率（NRE）、磷吸收效率（PRE）和 NRE:PRE 比值沿氮添加梯度显著下降。此外，我们发现衰老组织对氮磷比的反应比绿色组织更敏感；植物内部氮磷失衡的加剧主要是由于养分吸收，尤其是氮吸收效率的不成比例降低。总之，我们的研究表明，NRE 和 PRE 的差异进一步加剧了植物窝内氮磷失衡。
{"title":"Nutrient resorption exacerbates nitrogen–phosphorus imbalances in plants under increasing nitrogen addition in a saline-alkaline grassland","authors":"Yuan Su, Shuaikai Wu, Jie Hao, Huajie Diao, Kuanhu Dong, Changhui Wang","doi":"10.1093/jpe/rtad049","DOIUrl":"https://doi.org/10.1093/jpe/rtad049","url":null,"abstract":"\u0000 Reabsorbing nutrients from senescent tissues before leaf falling has been recognized as a strategy to adapt to nutrient deficiency. However, how nutrient resorption modulates the nitrogen (N)–phosphorus (P) balance inside plants remains unclear, especially under increased soil N availability. We examined the impacts of N addition at varying rates (0–32 g N m−2 yr−1) on nutrient resorption and the performance of nutrient resorption on controlling the internal N–P balance in the leaf and stem of a dominant grass species, Leymus secalinus, in a saline-alkaline grassland in northern China. After 6 years of N addition, N concentration and N:P ratio in green and senesced tissues (leaf and stem) rose with increasing N addition. The P concentration in green tissues decreased, but did not significantly change in senesced tissues with increasing N addition. The N resorption efficiency (NRE), P resorption efficiency (PRE) and NRE:PRE ratio significantly decreased along the N addition gradient. Moreover, we found more sensitive responses of N:P ratio in senesced tissues than in green tissues; such exacerbation of plant internal N–P imbalances mainly resulted from a disproportionate reduction in nutrient resorption, especially NRE. Overall, our study suggested that differences in NRE and PRE further exacerbated the internal N–P imbalances in plant litters.","PeriodicalId":503671,"journal":{"name":"Journal of Plant Ecology","volume":"10 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139386354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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