High ecosystem stability of evergreen broadleaf forests under severe droughts
High ecosystem stability of evergreen broadleaf forests under severe droughts
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严重干旱下常绿阔叶林生态系统稳定性高
DOI：
10.1111/gcb.14748
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发表时间：
2019-07-27
影响因子：
11.6
通讯作者：
Xia, Jianyang
中科院分区：
文献类型：
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作者：
Huang, Kun;Xia, Jianyang
全球干旱事件的增加威胁着陆地生态系统功能的稳定性。常绿阔叶林(EBF)一年四季都有树叶，因此可能比其他生物群经历更高的干旱风险。然而，近期全球植被生产力或陆地碳汇的时间变异性主要是由非常绿生态系统驱动的，如半干旱草原、农田和北方森林。因此，我们假设在日益严重的干旱条件下，EBF比其他生物群具有更高的稳定性。在这里，我们使用长期标准化降水和蒸发指数(SPII)数据和卫星衍生的增强型植被指数(EVI)产品来量化生物群和全球尺度的时间稳定性(年平均EVI与其SD的比率)、抗性(在干旱期间保持其原始水平的能力)和恢复力(EVI恢复到干旱前的水平的速率)。我们发现，在2000年至2014年期间，年干旱严重程度(SPI范围：−0.08至−1.8)、面积(面积比例范围：2%-19%)和持续时间(月范围：7.9-9.1)有显著增加的趋势。然而，EBF显示出EVI对干旱的最高抗性，但不同生物群(森林、草原、稀树草原和灌丛)的EVI对干旱的抵抗力没有显著差异。全球环境变化指数对干旱的抵抗力和复原力在很大程度上受到温度和太阳辐射的影响。这些发现表明，尽管有更大的干旱暴露，EBF比其他生物群具有更高的稳定性。因此，在未来更强烈的气候极端情况下，EBF的保护对于稳定全球植被生产力和土地碳汇至关重要。
Global increase in drought occurrences threatens the stability of terrestrial ecosystem functioning. Evergreen broadleaf forests (EBFs) keep leaves throughout the year, and therefore could experience higher drought risks than other biomes. However, the recent temporal variability of global vegetation productivity or land carbon sink is mainly driven by non‐evergreen ecosystems, such as semiarid grasslands, croplands, and boreal forests. Thus, we hypothesize that EBFs have higher stability than other biomes under the increasingly extreme droughts. Here we use long‐term Standardized Precipitation and Evaporation Index (SPEI) data and satellite‐derived Enhanced Vegetation Index (EVI) products to quantify the temporal stability (ratio of mean annual EVI to its SD), resistance (ability to maintain its original levels during droughts), and resilience (rate of EVI recovering to pre‐drought levels) at biome and global scales. We identified significantly increasing trends of annual drought severity (SPEI range: −0.08 to −1.80), area (areal fraction range: 2%–19%), and duration (month range: 7.9–9.1) in the EBF biome over 2000–2014. However, EBFs showed the highest resistance of EVI to droughts, but no significant differences in resilience of EVI to droughts were found among biomes (forests, grasslands, savannas, and shrublands). Global resistance and resilience of EVI to droughts were largely affected by temperature and solar radiation. These findings suggest that EBFs have higher stability than other biomes despite the greater drought exposure. Thus, the conservation of EBFs is critical for stabilizing global vegetation productivity and land carbon sink under more‐intense climate extremes in the future.