量化气候因素如何影响植被物候对于理解全球变化背景下气候-植被相互作用以及碳水循环至关重要.然而,不同强度的极端气候事件对青藏高原植被物候的影响尚不明确.利用长期日光诱导叶绿素荧光遥感,研究了2000~2018年青藏高原植被物候对不...量化气候因素如何影响植被物候对于理解全球变化背景下气候-植被相互作用以及碳水循环至关重要.然而,不同强度的极端气候事件对青藏高原植被物候的影响尚不明确.利用长期日光诱导叶绿素荧光遥感,研究了2000~2018年青藏高原植被物候对不同强度极端温度和降水事件的响应.研究发现,随着温度梯度的增加,最高温度暴露天数(Maximum temperature exposure days,TxED)和最低温度暴露天数(Minimum temperature exposure days,TnED)均导致春季物候(Start of the growing season,SOS)由延迟转为提前.然而,TxED和TnED对秋季物候(end of the growing season,EOS)的影响随着温度梯度的增加由提前转为延迟,直到达到温度阈值.超过该温度阈值将会对植被生长产生不利影响,引起EOS提前结束.具体而言,对应的最高和最低温度阈值分别为10.12℃和2.54℃.对于累积降水(Cumulative precipitation,CP),随着降水梯度增加会促进SOS提前和EOS延迟,但对SOS提前的效应逐渐减弱.不同类型植被的物候对不同气候的响应趋势相似,但其最适气候条件不同.通常来说,草甸和草原植被生长的最适温度和降水低于森林和灌木.这些发现揭示了植被物候对不同强度极端气候事件的差异化响应,意味着青藏高原植被春季物候将继续随着气候变暖而持续提前,而部分区域的秋季物候可能随着持续变暖出现从延迟向提前的转变.展开更多
In many arid ecosystems,vegetation frequently occurs in high-cover patches interspersed in a matrix of low plant cover.However,theoretical explanations for shrub patch pattern dynamics along climate gradients remain u...In many arid ecosystems,vegetation frequently occurs in high-cover patches interspersed in a matrix of low plant cover.However,theoretical explanations for shrub patch pattern dynamics along climate gradients remain unclear on a large scale.This context aimed to assess the variance of the Reaumuria soongorica patch structure along the precipitation gradient and the factors that affect patch structure formation in the middle and lower Heihe River Basin(HRB).Field investigations on vegetation patterns and heterogeneity in soil properties were conducted during 2014 and 2015.The results showed that patch height,size and plant-to-patch distance were smaller in high precipitation habitats than in low precipitation sites.Climate,soil and vegetation explained 82.5% of the variance in patch structure.Spatially,R.soongorica shifted from a clumped to a random pattern on the landscape towards the MAP gradient,and heterogeneity in the surface soil properties(the ratio of biological soil crust(BSC) to bare gravels(BG)) determined the R.soongorica population distribution pattern in the middle and lower HRB.A conceptual model,which integrated water availability and plant facilitation and competition effects,was revealed that R.soongorica changed from a flexible water use strategy in high precipitation regions to a consistent water use strategy in low precipitation areas.Our study provides a comprehensive quantification of the variance in shrub patch structure along a precipitation gradient and may improve our understanding of vegetation pattern dynamics in the Gobi Desert under future climate change.展开更多
文摘量化气候因素如何影响植被物候对于理解全球变化背景下气候-植被相互作用以及碳水循环至关重要.然而,不同强度的极端气候事件对青藏高原植被物候的影响尚不明确.利用长期日光诱导叶绿素荧光遥感,研究了2000~2018年青藏高原植被物候对不同强度极端温度和降水事件的响应.研究发现,随着温度梯度的增加,最高温度暴露天数(Maximum temperature exposure days,TxED)和最低温度暴露天数(Minimum temperature exposure days,TnED)均导致春季物候(Start of the growing season,SOS)由延迟转为提前.然而,TxED和TnED对秋季物候(end of the growing season,EOS)的影响随着温度梯度的增加由提前转为延迟,直到达到温度阈值.超过该温度阈值将会对植被生长产生不利影响,引起EOS提前结束.具体而言,对应的最高和最低温度阈值分别为10.12℃和2.54℃.对于累积降水(Cumulative precipitation,CP),随着降水梯度增加会促进SOS提前和EOS延迟,但对SOS提前的效应逐渐减弱.不同类型植被的物候对不同气候的响应趋势相似,但其最适气候条件不同.通常来说,草甸和草原植被生长的最适温度和降水低于森林和灌木.这些发现揭示了植被物候对不同强度极端气候事件的差异化响应,意味着青藏高原植被春季物候将继续随着气候变暖而持续提前,而部分区域的秋季物候可能随着持续变暖出现从延迟向提前的转变.
基金National Natural Science Foundation of China,No.91425301,No.41730854The PCSIRT,No.IRT-15R06Scientific Research Starting Foundation for Doctors in Hebei GEO University,No.BQ2017003
文摘In many arid ecosystems,vegetation frequently occurs in high-cover patches interspersed in a matrix of low plant cover.However,theoretical explanations for shrub patch pattern dynamics along climate gradients remain unclear on a large scale.This context aimed to assess the variance of the Reaumuria soongorica patch structure along the precipitation gradient and the factors that affect patch structure formation in the middle and lower Heihe River Basin(HRB).Field investigations on vegetation patterns and heterogeneity in soil properties were conducted during 2014 and 2015.The results showed that patch height,size and plant-to-patch distance were smaller in high precipitation habitats than in low precipitation sites.Climate,soil and vegetation explained 82.5% of the variance in patch structure.Spatially,R.soongorica shifted from a clumped to a random pattern on the landscape towards the MAP gradient,and heterogeneity in the surface soil properties(the ratio of biological soil crust(BSC) to bare gravels(BG)) determined the R.soongorica population distribution pattern in the middle and lower HRB.A conceptual model,which integrated water availability and plant facilitation and competition effects,was revealed that R.soongorica changed from a flexible water use strategy in high precipitation regions to a consistent water use strategy in low precipitation areas.Our study provides a comprehensive quantification of the variance in shrub patch structure along a precipitation gradient and may improve our understanding of vegetation pattern dynamics in the Gobi Desert under future climate change.
