Recovery: Fast and Slow—Vegetation Response During the 2012–2016 California Drought
Recovery: Fast and Slow—Vegetation Response During the 2012–2016 California Drought
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DOI：
10.1029/2020jg005976
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发表时间：
2021-03
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影响因子：
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通讯作者：
Xi Yang;Xiangtao Xu;A. Stovall;Min Chen;Jung‐Eun Lee
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文献类型：
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作者：
Xi Yang;Xiangtao Xu;A. Stovall;Min Chen;Jung‐Eun Lee
2012-2016年加州干旱严重影响了大范围环境梯度的自然植被。虽然有几项研究报告了植物水分胁迫和死亡率的增加，但生态系统生产力反应的时空变化以及相关的环境和生物驱动因素仍不清楚。在这里，使用中分辨率成像光谱仪的增强植被指数，我们发现45%的自然生态系统在2012-2016年期间表现出生产力的突变（断点[BP]）。生产力反应有三种主要的对比时间模式：（i）在较高的温度下稳定增加，然后由于累积的水分耗尽而下降（高海拔森林）或温度降低（ii）干旱胁迫期间逐渐下降，干旱胁迫部分缓解后1年内迅速恢复，及（iii）逐渐下降及突然下降。突变的幅度与初始渐变呈负相关（r =-0.80，p < 0.001）。总体而言，BP期间的变化平均抵消了之前渐进反应的57%。生态系统响应模式的空间变异性是由环境和生物因素驱动的。森林的正BP主要由降水量的增加和气温的降低所驱动，而负BP则主要由降水量的异常所驱动。到2019年，33%的自然植被恢复到2010年的生态脆弱性水平。生态系统对多年干旱的反应可以以复杂的方式影响生态系统动态。应考虑多种生态水文因素，以了解和预测干旱对生态系统的长期影响。
The 2012–2016 California Drought severely impacted natural vegetation across a wide range of environmental gradient. Although several studies have reported an increase in plant water stress and mortality, the spatiotemporal variations of ecosystem productivity responses and the associated environmental and biological drivers remain unclear. Here, using Enhanced Vegetation Index from the Moderate resolution imaging spectrometer, we found that 45% of the natural ecosystems showed an abrupt change (breakpoint [BP]) in productivity during 2012–2016. There were three major contrasting temporal patterns of productivity responses: (i) a steady increase under higher temperature followed by a decline due to accumulated moisture depletion (high elevation forest) or temperature decrease (high elevation nonforest), (ii) gradual decline during the drought followed by a rapid recovery within 1 year after drought stress was partially relieved, and (iii) both a gradual decline and an abrupt decline. The magnitude of abrupt changes was negatively correlated (r = −0.80, p < 0.001) with initial gradual changes. Overall, changes during BP offset, on average, 57% of the preceding gradual responses. The spatial variability in ecosystem response patterns is driven by both environmental and biological factors. Particularly, for forests, positive BP was driven by increasing rainfall and decreasing temperature, while negative BP was mainly driven by the precipitation anomaly. By 2019, 33% of the natural vegetation have recovered to the level of EVI in 2010. Ecosystem responses to multiyear droughts can influence ecosystem dynamics in a complex pattern. Multiple ecohydrological factors should be considered to understand and predict the long‐term drought impacts on ecosystems.