Drought significantly constrains vegetation growth and reduces terrestrial carbon sinks.Currently,the spatiotemporal patterns and mechanisms of the differential impacts of soil and meteorological droughts on vegetatio...Drought significantly constrains vegetation growth and reduces terrestrial carbon sinks.Currently,the spatiotemporal patterns and mechanisms of the differential impacts of soil and meteorological droughts on vegetation productivity remain inadequately understood.In this study,we analyzed soil moisture(SM),vapor pressure deficit(VPD),and gross primary productivity(GPP)to investigate their spatiotemporal patterns and the combined effects on GPP over China.The results revealed that:(1)Soil drought and meteorological drought generally exhibited temporally synchronous trends across China.(2)GPP was predominantly affected by the combined and synchronous effects of both SM and VPD,although their effects displayed directional variability differences in certain regions.(3)SM demonstrated a greater relative importance on GPP than VPD across more than half of the regions in China,whereas deciduous broadleaf forests were the only vegetation type primarily affected by VPD.(4)Under the lag effects,both SM and VPD exhibited bidirectional Granger causality with GPP,with the interaction between VPD and GPP proving more pronounced than that of SM.Our research provides valuable insights into the mechanisms through which SM and VPD influence GPP,contributing to improved predictions vegetation productivity and implementing ecological restoration.展开更多
Understanding the characteristics and driving factors behind changes in vegetation ecosystem resilience is crucial for mitigating both current and future impacts of climate change. Despite recent advances in resilienc...Understanding the characteristics and driving factors behind changes in vegetation ecosystem resilience is crucial for mitigating both current and future impacts of climate change. Despite recent advances in resilience research, significant knowledge gaps remain regarding the drivers of resilience changes. In this study, we investigated the dynamics of ecosystem resilience across China and identified potential driving factors using the kernel normalized difference vegetation index(kNDVI) from 2000 to 2020. Our results indicate that vegetation resilience in China has exhibited an increasing trend over the past two decades, with a notable breakpoint occurring around 2012. We found that precipitation was the dominant driver of changes in ecosystem resilience, accounting for 35.82% of the variation across China, followed by monthly average maximum temperature(Tmax) and vapor pressure deficit(VPD), which explained 28.95% and 28.31% of the variation, respectively. Furthermore, we revealed that daytime and nighttime warming has asymmetric impacts on vegetation resilience, with temperature factors such as Tmin and Tmax becoming more influential, while the importance of precipitation slightly decreases after the resilience change point. Overall, our study highlights the key roles of water availability and temperature in shaping vegetation resilience and underscores the asymmetric effects of daytime and nighttime warming on ecosystem resilience.展开更多
植被物候是监测陆地生态系统和全球气候变化的重要生物指标。基于经典遥感植被指数的陆表物候监测在不同植被类型的精确分析方面存在较大挑战,日光诱导叶绿素荧光(SIF)可以直接反映植被实际光合作用的动态变化,能够更精确地刻画出植被...植被物候是监测陆地生态系统和全球气候变化的重要生物指标。基于经典遥感植被指数的陆表物候监测在不同植被类型的精确分析方面存在较大挑战,日光诱导叶绿素荧光(SIF)可以直接反映植被实际光合作用的动态变化,能够更精确地刻画出植被的年际变异。本研究基于2001~2020年GOSIF数据集,通过D-L拟合函数和动态阈值法提取东北地区植被物候参数,结合一元线性回归分析、稳定性和持续性分析,在多时空尺度下分析2001~2020年东北地区植被物候的时空演变特征,并探讨植被物候对气候变化的响应机制。结果表明:(1)植被生长季开始(Start of Season,SOS)、结束(EndofSeason,EOS)、生长季长度(LengthofSeason,LOS)和生长峰值(Position of Peak,POP)整体上分别呈现出提前、推迟、延长和提前趋势;(2)草丛SOS提前、EOS推迟趋势较为显著,针叶林EOS提前趋势显著;SOS提前、EOS推迟导致LOS延长,除针叶林外,所有植被类型LOS均呈现出延长趋势;除草丛和草原外,其余植被类型POP均呈提前趋势;(3)20年来植被SOS、EOS、LOS和POP变化较为稳定,变异系数均小于0.1;(4)大部分区域植被SOS、EOS、LOS和POP的H值介于0.35~0.5之间,说明其变化趋势与过去相反,将呈现微弱延迟、提前、缩短和延长的趋势;(5)整体上气温和降水对植被物候的影响机制相反,即气温升高(降水增加)导致SOS和POP提前(推迟)、EOS推迟(提前)以及LOS延长(缩短);相对湿度与植被物候参数均呈负相关关系。本研究结果有助于理解植被进行光合作用的时空格局变化及对气候变化的响应机制,也为东北地区生态环境的评估和管理提供参考。展开更多
Changes in surface temperature extremes have become a global concern.Based on the daily lowest temperature(TN)and daily highest temperature(TX)data from 2138weather stations in China from 1961 to 2020,we calculated 14...Changes in surface temperature extremes have become a global concern.Based on the daily lowest temperature(TN)and daily highest temperature(TX)data from 2138weather stations in China from 1961 to 2020,we calculated 14 extreme temperature indices to analyze the characteristics of extreme temperature events.The widespread changes observed in all extreme temperature indices suggest that China experienced significant warming during this period.Specifically,the cold extreme indices,such as cold nights,cold days,frost days,icing days,and the cold spell duration index,decreased significantly by-6.64,-2.67,-2.96,-0.97,and-1.01 days/decade,respectively.In contrast,we observed significant increases in warm extreme indices.The number of warm nights,warm days,summer days,tropical nights,and warm spell duration index increased by 8.44,5.18,2.81,2.50,and 1.66d/decade,respectively.In addition,the lowest TN,highest TN,lowest TX,and highest TX over the entire period rose by 0.47,0.22,0.26,and 0.16℃/decade,respectively.Furthermore,using Pearson's correlation and wavelet coherence analyses,this study identified a strong association between extreme temperature indices and atmospheric circulation factors,with varying correlation strengths and resonance periods across different time-frequency domains.展开更多
基金National Key Research and Development Program,No.2021xjkk0303。
文摘Drought significantly constrains vegetation growth and reduces terrestrial carbon sinks.Currently,the spatiotemporal patterns and mechanisms of the differential impacts of soil and meteorological droughts on vegetation productivity remain inadequately understood.In this study,we analyzed soil moisture(SM),vapor pressure deficit(VPD),and gross primary productivity(GPP)to investigate their spatiotemporal patterns and the combined effects on GPP over China.The results revealed that:(1)Soil drought and meteorological drought generally exhibited temporally synchronous trends across China.(2)GPP was predominantly affected by the combined and synchronous effects of both SM and VPD,although their effects displayed directional variability differences in certain regions.(3)SM demonstrated a greater relative importance on GPP than VPD across more than half of the regions in China,whereas deciduous broadleaf forests were the only vegetation type primarily affected by VPD.(4)Under the lag effects,both SM and VPD exhibited bidirectional Granger causality with GPP,with the interaction between VPD and GPP proving more pronounced than that of SM.Our research provides valuable insights into the mechanisms through which SM and VPD influence GPP,contributing to improved predictions vegetation productivity and implementing ecological restoration.
基金National Key Research and Development Program,No.2021xjkk0303。
文摘Understanding the characteristics and driving factors behind changes in vegetation ecosystem resilience is crucial for mitigating both current and future impacts of climate change. Despite recent advances in resilience research, significant knowledge gaps remain regarding the drivers of resilience changes. In this study, we investigated the dynamics of ecosystem resilience across China and identified potential driving factors using the kernel normalized difference vegetation index(kNDVI) from 2000 to 2020. Our results indicate that vegetation resilience in China has exhibited an increasing trend over the past two decades, with a notable breakpoint occurring around 2012. We found that precipitation was the dominant driver of changes in ecosystem resilience, accounting for 35.82% of the variation across China, followed by monthly average maximum temperature(Tmax) and vapor pressure deficit(VPD), which explained 28.95% and 28.31% of the variation, respectively. Furthermore, we revealed that daytime and nighttime warming has asymmetric impacts on vegetation resilience, with temperature factors such as Tmin and Tmax becoming more influential, while the importance of precipitation slightly decreases after the resilience change point. Overall, our study highlights the key roles of water availability and temperature in shaping vegetation resilience and underscores the asymmetric effects of daytime and nighttime warming on ecosystem resilience.
文摘植被物候是监测陆地生态系统和全球气候变化的重要生物指标。基于经典遥感植被指数的陆表物候监测在不同植被类型的精确分析方面存在较大挑战,日光诱导叶绿素荧光(SIF)可以直接反映植被实际光合作用的动态变化,能够更精确地刻画出植被的年际变异。本研究基于2001~2020年GOSIF数据集,通过D-L拟合函数和动态阈值法提取东北地区植被物候参数,结合一元线性回归分析、稳定性和持续性分析,在多时空尺度下分析2001~2020年东北地区植被物候的时空演变特征,并探讨植被物候对气候变化的响应机制。结果表明:(1)植被生长季开始(Start of Season,SOS)、结束(EndofSeason,EOS)、生长季长度(LengthofSeason,LOS)和生长峰值(Position of Peak,POP)整体上分别呈现出提前、推迟、延长和提前趋势;(2)草丛SOS提前、EOS推迟趋势较为显著,针叶林EOS提前趋势显著;SOS提前、EOS推迟导致LOS延长,除针叶林外,所有植被类型LOS均呈现出延长趋势;除草丛和草原外,其余植被类型POP均呈提前趋势;(3)20年来植被SOS、EOS、LOS和POP变化较为稳定,变异系数均小于0.1;(4)大部分区域植被SOS、EOS、LOS和POP的H值介于0.35~0.5之间,说明其变化趋势与过去相反,将呈现微弱延迟、提前、缩短和延长的趋势;(5)整体上气温和降水对植被物候的影响机制相反,即气温升高(降水增加)导致SOS和POP提前(推迟)、EOS推迟(提前)以及LOS延长(缩短);相对湿度与植被物候参数均呈负相关关系。本研究结果有助于理解植被进行光合作用的时空格局变化及对气候变化的响应机制,也为东北地区生态环境的评估和管理提供参考。
基金National Key Research and Development Program of China,No.2021YFB3900900。
文摘Changes in surface temperature extremes have become a global concern.Based on the daily lowest temperature(TN)and daily highest temperature(TX)data from 2138weather stations in China from 1961 to 2020,we calculated 14 extreme temperature indices to analyze the characteristics of extreme temperature events.The widespread changes observed in all extreme temperature indices suggest that China experienced significant warming during this period.Specifically,the cold extreme indices,such as cold nights,cold days,frost days,icing days,and the cold spell duration index,decreased significantly by-6.64,-2.67,-2.96,-0.97,and-1.01 days/decade,respectively.In contrast,we observed significant increases in warm extreme indices.The number of warm nights,warm days,summer days,tropical nights,and warm spell duration index increased by 8.44,5.18,2.81,2.50,and 1.66d/decade,respectively.In addition,the lowest TN,highest TN,lowest TX,and highest TX over the entire period rose by 0.47,0.22,0.26,and 0.16℃/decade,respectively.Furthermore,using Pearson's correlation and wavelet coherence analyses,this study identified a strong association between extreme temperature indices and atmospheric circulation factors,with varying correlation strengths and resonance periods across different time-frequency domains.
