Forest vulnerability to drought controlled by bedrock composition
Forest vulnerability to drought controlled by bedrock composition
复制标题
DOI：
10.1038/s41561-022-01012-2
复制
发表时间：
2022-09-06
影响因子：
18.3
通讯作者：
Holbrook, W. Steven
中科院分区：
文献类型：
--
作者：
Callahan, Russell P.;Riebe, Clifford S.;Holbrook, W. Steven
根据对一系列地质上不同地点的干旱响应的分析，2011年至2017年加利福尼亚州严重干旱期间森林枯死的空间变异可以通过基岩成分的变化和耐候性来解释。森林正日益受到气候变化引发的干旱、枯死和野火循环的威胁。然而，由于尚不完全清楚的原因，一些林分比其他林分更脆弱，在干旱后留下了各种枯死和野火风险的拼凑。在这里，我们发现森林干旱响应的空间变异可以用下垫基岩的差异来解释。我们的分析将2011-2017年加州干旱期间基岩成分的地球化学测量、地下风化的地球物理测量和蒸散发的遥感变化联系起来。我们发现，在扎根于风化、营养丰富的基岩的茂密森林中，蒸散量急剧下降。相比之下，相对未风化、营养贫乏的基岩支撑着在干旱中毫发无损的薄薄的森林。基岩成分通过影响地下风化和养分供应，调节山地生态系统储水量和需水量的平衡。然而，基岩并没有通过提供更多的储水能力来增强森林对干旱的抵御能力，相反，具有更多耐候性和营养丰富的矿物质的基岩导致了一个盛衰循环，在这个循环中，湿润年份较高的生态系统生产力导致干旱期间植物对水的需求过剩，从而导致了更大的脆弱性。
Spatial variability in forest dieback during the severe drought in California between 2011 and 2017 can be explained by variations in bedrock composition and thus weatherability, according to analyses of the drought responses a series of geologically distinct sites.Forests are increasingly threatened by climate-change-fuelled cycles of drought, dieback and wildfires. However, for reasons that remain incompletely understood, some forest stands are more vulnerable than others, leaving a patchwork of varying dieback and wildfire risk after drought. Here, we show that spatial variability in forest drought response can be explained by differences in underlying bedrock. Our analysis links geochemical measurements of bedrock composition, geophysical measurements of subsurface weathering and remotely sensed changes in evapotranspiration during the 2011-2017 drought in California. We find that evapotranspiration plummeted in dense forest stands rooted in weathered, nutrient-rich bedrock. By contrast, relatively unweathered, nutrient-poor bedrock supported thin forest stands that emerged unscathed from the drought. By influencing both subsurface weathering and nutrient supply, bedrock composition regulates the balance of water storage and demand in mountain ecosystems. However, rather than enhancing forest resilience to drought by providing more water-storage capacity, bedrock with more weatherable and nutrient-rich minerals induced greater vulnerability by enabling a boom-bust cycle in which higher ecosystem productivity during wet years drives excess plant water demand during droughts.