Recent Tree Mortality Dampens Semi‐Arid Forest Die‐Off During Subsequent Drought
Recent Tree Mortality Dampens Semi‐Arid Forest Die‐Off During Subsequent Drought
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最近的树木死亡率减少了半干旱森林在随后的干旱期间的死亡
DOI：
10.1029/2022av000810
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发表时间：
2023
期刊：
影响因子：
8.4
通讯作者：
Goulden, Michael L.
中科院分区：
文献类型：
--
作者：
Norlen, Carl A.;Goulden, Michael L.
气候变化预计将增加干旱的强度和频率，人们普遍预测这将威胁到森林的生存。大多数森林死亡预测假设最近的树木死亡率不会改变随后干旱期间的死亡严重程度。我们通过比较加州2012-2015年遭受单一干旱（“仅第二次干旱”）的半干旱针叶林林与1999-2002年和2012-2015年经历干旱（“两次干旱”）的林分的死亡来验证这一假设。我们将死亡严重程度量化为卫星观测到的归一化差异水分指数的减少，并将累积水分亏缺量化为负4年降水量减去蒸散量（4年Pr‐ET透支）。在这里，我们表明，最近的树木死亡率降低了暴露于随后的干旱的半干旱针叶林的死亡严重程度。在2012-2015年，第二次干旱样本中的林分经历了与极端的4年Pr‐ET透支相关的严重死亡。两次干旱样本中的林分在1999-2002年经历了严重的死亡和4年的Pr‐ET透支，但在2012-2015年，尽管持续4年的Pr‐ET透支，但死亡相对较少。我们将其解释为一种抑制效应，即先前的树木死亡减少了随后干旱暴露期间森林死亡的严重程度。由于森林继续受到与气候变化有关的干扰，抑制效应将对反复干旱的影响施加短暂的，也许是长期的限制。
Climate change is expected to increase drought intensity and frequency, which are commonly predicted will threaten the survival of forests. Most forest die‐off projections assume that recent tree mortality will not alter die‐off severity during subsequent droughts. We tested this assumption by comparing die‐off in semi‐arid conifer forest stands in California that were exposed to a single drought in 2012–2015 (“2ndDrought Only”) with forest stands that experienced drought in both 1999–2002 and 2012–2015 (“Both Droughts”). We quantified die‐off severity as a reduction in the satellite observed Normalized Difference Moisture Index, and cumulative moisture deficit as negative 4‐year Precipitation minus Evapotranspiration (4‐year Pr‐ET overdraft). Here we show that recent tree morality reduces die‐off severity in semi‐arid conifer forests exposed to subsequent drought. Stands in the2ndDrought Onlysample experienced severe die‐off associated with extreme 4‐year Pr‐ET overdraft in 2012–2015. Stands in theBoth Droughtssample experienced severe die‐off and 4‐year Pr‐ET overdraft in 1999–2002, but comparatively little 2012–2015 die‐off despite continued 4‐year Pr‐ET overdraft. We interpret this as a dampening effect, where prior tree mortality reduces forest die‐off severity during subsequent drought exposure. As forests continue to experience disturbances linked to climate change, dampening effects will impose a transient, and perhaps long‐term, constraint on the impact of repeated drought.
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影响因子：
30.7
作者：
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影响因子：
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影响因子：
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作者：
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