Multiyear drought-induced morbidity preceding tree death in southeastern US forests
Multiyear drought-induced morbidity preceding tree death in southeastern US forests
复制标题
DOI：
10.1890/15-0274
复制
发表时间：
2016-01-01
影响因子：
5
通讯作者：
Clark, James S.
中科院分区：
文献类型：
--
作者：
Berdanier, Aaron B.;Clark, James S.
最近的森林枯死，加上未来干旱的威胁，重点关注树木死亡是由灾难性事件造成的程度，而不是多年积累的健康状况的慢性下降。虽然最近的注意力集中在大规模的枯死上，但令人关切的是，日益严重的干旱压力和长期发病率可能对许多地区的森林构成产生普遍影响。在这里，我们使用来自美国东南部森林的长期全林分库存数据来表明，暴露于干旱的树木在死亡之前经历多年的生长下降。在一次严重的多年干旱之后，72%没有恢复干旱前生长速度的树木在10年内死亡。这种模式是由当地的水分供应介导的。作为死亡前发病率的指标，我们计算了干旱后相对于存活同种的累积生长差异。干旱引起的发病率的强度各不相同的物种，并与耐旱性。这些发现支持了树木在干旱事件中避免死亡的能力，但也表明了几十年来可能发生的变化。在这些生态系统中，干旱后的树木死亡率是可以预测的，这是基于生长下降，突出了在模型、实验和管理决策中解决多年干旱引起的发病率的机会。
Recent forest diebacks, combined with threats of future drought, focus attention on the extent to which tree death is caused by catastrophic events as opposed to chronic declines in health that accumulate over years. While recent attention has focused on large-scale diebacks, there is concern that increasing drought stress and chronic morbidity may have pervasive impacts on forest composition in many regions. Here we use long-term, whole-stand inventory data from southeastern U.S. forests to show that trees exposed to drought experience multiyear declines in growth prior to mortality. Following a severe, multiyear drought, 72% of trees that did not recover their pre-drought growth rates died within 10 yr. This pattern was mediated by local moisture availability. As an index of morbidity prior to death, we calculated the difference in cumulative growth after drought relative to surviving conspecifics. The strength of drought-induced morbidity varied among species and was correlated with drought tolerance. These findings support the ability of trees to avoid death during drought events but indicate shifts that could occur over decades. Tree mortality following drought is predictable in these ecosystems based on growth declines, highlighting an opportunity to address multiyear drought-induced morbidity in models, experiments, and management decisions.