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【学术报告】Dr.Ming Pan, Department of Civil and Environmental Engineering, Princeton University,USA

报告题目:陆地水文对热带雨林光合作用的影响

报告人:Dr. Ming Pan

单位:Department of Civil and Environmental Engineering, Princeton University, USA

时间:2015320日上午10:00

地点:大气所40号楼319会议室

 

摘要:The response of tropical forests to droughts is highly uncertain. During the dry season,

canopy photosynthesis of some tropical forests can decline, whereas in others it can be maintained

at the same or a higher level than during the wet season. However, it remains uncertain to what

extent water availability is responsible for productivity declines of tropical forests during the dry

season. Here we use global satellite observations of two independent measures of vegetation

photosynthetic properties (enhanced vegetation index from 2002 to 2012 and solar-induced

chlorophyll fluorescence from 2007 to 2012) to investigate links between hydroclimate and tropical

forest productivity. We find that above an annual rainfall threshold of approximately 2,000 mm yr1,

 the evergreen state is sustained during the dry season in tropical rainforests worldwide, whereas

below that threshold, this is not the case. Through a water-budget analysis of precipitation,

potential evapotranspiration and satellite measurements of water storage change, we demonstrate

that this threshold determines whether the supply of seasonally redistributed subsurface water

storage from the wet season can satisfy plant water demands in the subsequent dry season. We

conclude that water availability exerts a first-order control on vegetation seasonality in tropical

forests globally. Our framework can also help identify where tropical forests may be vulnerable

or resilient to future hydroclimatic changes.


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