Academy of Forestry, Inner Mongolia Agricultural University, Huhhot, Inner Mongolia, China.
College of Urban and Environmental Sciences and MOE Laboratory for Earth Surface Processes, Peking University, Beijing, China.
PLoS One. 2018 Apr 6;13(4):e0195630. doi: 10.1371/journal.pone.0195630. eCollection 2018.
Worldwide tree mortality as induced by climate change presents a challenge to forest managers. To successfully manage vulnerable forests requires the capacity of regeneration to compensate for losses from tree mortality. We observed rapid regeneration and the growth release of young trees after warming-induced mortality in a David aspen-dominated (Populus davidiana) broad-leaved forest in Inner Mongolia, China, as based on individual tree measurements taken in 2012 and 2015 from a 6-ha permanent plot. Warming and drought stress killed large trees 10-15 m tall with a total number of 2881 trees during 2011-2012, and also thinned the upper crowns. David aspen recruitment increased 2 times during 2012-2015 and resulted in a high transition probability of David aspen replacing the same or other species, whereas the recruitment of Mongolian oak (Quercus mongolica) was much lower: it decreased from 2012 to 2015, indicating that rapid regeneration represented a regrowth phase for David aspen, and not succession to Mongolian oak. Further, we found that the recruitment density increased with canopy openness, thus implying that warming-induced mortality enhanced regeneration. Our results suggest that David aspen has a high regrowth ability to offset individual losses from warming-induced mortality. This important insight has implications for managing this vulnerable forest in the semi-arid region of northern China.
气候变化引起的全球树木死亡对森林管理者构成了挑战。要成功管理脆弱的森林，就需要有再生能力来弥补树木死亡造成的损失。我们在中国内蒙古的一片以山杨为主的（Populus davidiana）阔叶林中观察到，由于气候变暖导致树木死亡，树木的快速再生和生长释放得到了释放。这些观察结果是基于 2012 年和 2015 年在一个 6 公顷的永久样地中对每棵树进行的测量得出的。在 2011 年至 2012 年期间，变暖与干旱胁迫导致了 2881 棵 10-15 米高的大树死亡，并使树冠稀疏。在 2012 年至 2015 年期间，山杨的幼苗数量增加了两倍，导致山杨取代同一物种或其他物种的概率很高，而蒙古栎（Quercus mongolica）的幼苗数量则较低：从 2012 年到 2015 年减少了，这表明快速再生代表了山杨的再生阶段，而不是向蒙古栎的演替。此外，我们发现幼苗密度随树冠开阔度的增加而增加，这意味着气候变暖导致的树木死亡促进了再生。我们的研究结果表明，山杨具有较高的再生能力，可以抵消因气候变暖导致的个体死亡。这一重要发现对管理中国北方半干旱地区的这种脆弱森林具有重要意义。
