Extreme drought alters competitive dominance within and between tree species in a mixed forest stand
Extreme drought alters competitive dominance within and between tree species in a mixed forest stand
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DOI：
10.1111/1365-2435.12126
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发表时间：
2013-12-01
影响因子：
5.2
通讯作者：
Jump, Alistair S.
中科院分区：
文献类型：
--
作者：
Cavin, Liam;Mountford, Edward P.;Jump, Alistair S.
1.极端气候事件对生态系统的影响是生物应对气候变化的重要驱动因素。对于森林来说，极端干旱与诸如大规模死亡和初级生产减少等负面影响有关。然而，植物群落对极端干旱事件的反应仍然缺乏了解。我们使用了重点物种范围核心的长期监测方案的死亡率数据，结合树轮的年度生长数据，来研究极端干旱事件的影响和恢复。我们考察了种内和种间的干旱反应，并探索了差异反应如何影响优势种水曲柳和栓皮栎之间的竞争优势。最易受干旱影响的物种--西尔凡特种的死亡率在竞争导致的死亡率暂时下降的同时，导致两个物种的相对丰度发生了长期的变化。幸存的马尾松在干旱后的恢复过程中出现了显著的种内变异，并确定了两个不同的队列。较长的恢复期加上该物种未能恢复干旱前的生长水平，而对于Q.Petraea，没有观察到严重的干旱影响。相反，这一物种经历了竞争性的生长释放。我们的结果表明，生态系统对极端干旱的反应可能涉及恢复阶段和初始干旱影响期间的快速、非线性阈值过程。这些突然的变化可能导致群落内物种间优势地位的重新排序，如果极端事件变得更加频繁，这种情况可能会持续下去。
1. The effect of extreme climate events on ecosystems is an important driver of biotic responses to climate change. For forests, extreme drought has been linked to negative effects such as large-scale mortality and reduced primary production. However, the response of plant communities to extreme drought events remains poorly understood.2. We used mortality data from a long-term monitoring programme in the core of the focal species' ranges, in combination with annual growth data from tree-rings, to study the effect of, and recovery from, an extreme drought event. We examined both the intraspecific and interspecific drought response and explored how differential responses affect competitive dominance between the dominant species Fagus sylvatica and Quercus petraea.3. Mortality for the most drought-susceptible species, F.sylvatica, occurred alongside a temporary reduction in competition-induced mortality of Q.petraea, resulting in the long-term alteration of the relative abundance of the two species.4. Significant intraspecific variation occurred in post-drought recovery in surviving F.sylvatica, with two distinct cohorts identified. A prolonged recovery period was coupled with the failure to regain pre-drought growth levels in this species, whereas for Q.petraea, no severe drought impacts were observed. This species instead experienced competitive release of growth.5. Our results demonstrate that ecosystem responses to extreme drought can involve rapid, nonlinear threshold processes during the recovery phase as well as the initial drought impact. These sudden changes can lead to the reordering of dominance between species within communities, which may persist if extreme events become more frequent.