| 英文摘要： |
Quantifying drought-induced ecosystem vulnerability, e.g. in terms of plant productivity, based on vulnerability curves and coupled processes is a frontier issue and a challenge in the field of climate change risk. Primary productivity vulnerability to drought varies among and within ecosystem types, obscuring generalized patterns of ecological stability. Thus, we constructed drought vulnerability curves between aboveground net primary productivity (ANPP) and drought intensity for forest and grassland, through global data collection, bias checking, and systematic integration. Based on the improvement of theoretical analysis of ecosystem vulnerability and quantitative evaluation methods, we investigated the processes of sensitivity and adaptation to reveal vulnerability mechanisms. The ANPP was nonlinearly reduced along with drought intensity gradients, with an increasing trend for forests and a decreasing trend for grasslands. Under the same drought duration, both the forest and grassland ANPP decreased with increasing intensities (from light to severe drought). However, the forest and grassland ANPP exhibited divergent responses with durations under the same drought intensity. The combinations of drought duration and intensities also affected the ANPP. For example, negative responses of the grassland ANPP to increasing intensities differed among the durations (p = 0.001) and maximum occurred under the severe drought. Furthermore, we quantified the vulnerability by analyzing sensitivity and adaptation to short- (<= 3years) and long-term (> 3 years) drought. Grasslands showed higher sensitivity to short-term drought than to long-term drought, and the contrary for forests. Forests exhibited a certain adaptation to long-term drought, but to a lesser extent than grasslands. Comprehensively, grasslands presented lower vulnerability to growing-season drought with higher adaptation and lower sensitivity than forests. These findings suggest that quantitative assessment on ecosystem response to drought from the viewpoints of vulnerability curves and processes should be promoted in and coupled with future climate change risks and sustainable management of different ecosystems. |
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