Forest resilience to drought varies across biomes
Forest resilience to drought varies across biomes
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DOI：
10.1111/gcb.14082
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发表时间：
2018-05-01
影响因子：
11.6
通讯作者：
Galvan, J. Diego
中科院分区：
文献类型：
--
作者：
Gazol, Antonio;Julio Camarero, Jesus;Galvan, J. Diego
预计干旱频率和严重程度的增加可能会导致全球森林生产力下降。物种对干旱世界的反应很可能受到其功能特征的影响。在这里，我们分析了森林的抗旱能力，使用广泛的网络树轮宽度数据和卫星图像。我们编制了代理的森林生长和生产力（TRWi，绝对过时的环宽指数; NDVI，归一化差异植被指数）为11个树种和502个森林在西班牙对应的地中海，温带和大陆生物群系。基于1986年、1994-1995年、1999年和2005年4次主要干旱发生前、发生时和发生后的TRWi和NDVI数据，计算了森林抗旱能力的4个不同分量，并指出TRWi数据是比NDVI数据更敏感的森林抗旱能力指标。恢复力与干旱严重程度和森林组成有关。占主导地位的半干旱地中海森林的万年青裸子植物表现出最低的抗旱性，但较高的恢复比落叶被子植物占主导地位的湿温带森林。此外，半干旱裸子植物林的抗旱性呈负的时间趋势，但这种模式是在大陆和温带森林缺席。虽然裸子植物在干燥的地中海森林表现出更快的恢复干旱后，他们的恢复潜力可能会受到限制，如果干旱变得更加频繁。相反，生活在温带和大陆的被子植物和裸子植物可能在更强烈的干旱后难以恢复，因为它们能抵抗干旱，但在干旱后恢复的能力较低。
Forecasted increase drought frequency and severity may drive worldwide declines in forest productivity. Species-level responses to a drier world are likely to be influenced by their functional traits. Here, we analyse forest resilience to drought using an extensive network of tree-ring width data and satellite imagery. We compiled proxies of forest growth and productivity (TRWi, absolutely dated ring-width indices; NDVI, Normalized Difference Vegetation Index) for 11 tree species and 502 forests in Spain corresponding to Mediterranean, temperate, and continental biomes. Four different components of forest resilience to drought were calculated based on TRWi and NDVI data before, during, and after four major droughts (1986, 1994-1995, 1999, and 2005), and pointed out that TRWi data were more sensitive metrics of forest resilience to drought than NDVI data. Resilience was related to both drought severity and forest composition. Evergreen gymnosperms dominating semi-arid Mediterranean forests showed the lowest resistance to drought, but higher recovery than deciduous angiosperms dominating humid temperate forests. Moreover, semi-arid gymnosperm forests presented a negative temporal trend in the resistance to drought, but this pattern was absent in continental and temperate forests. Although gymnosperms in dry Mediterranean forests showed a faster recovery after drought, their recovery potential could be constrained if droughts become more frequent. Conversely, angiosperms and gymnosperms inhabiting temperate and continental sites might have problems to recover after more intense droughts since they resist drought but are less able to recover afterwards.