Dryness decreases average growth rate and increases drought sensitivity of Mongolia oak trees in North China
Dryness decreases average growth rate and increases drought sensitivity of Mongolia oak trees in North China
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DOI：
10.1016/j.agrformet.2021.108611
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发表时间：
2021-10
影响因子：
6.2
通讯作者：
Xianliang Zhang;Pengcheng Lv;Chen Xu;Xuanrui Huang;T. Rademacher
中科院分区：
文献类型：
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作者：
Xianliang Zhang;Pengcheng Lv;Chen Xu;Xuanrui Huang;T. Rademacher
蒙古栎是我国北方阔叶林中广泛分布的树种，对日益严重的干旱灾害十分敏感。据报道，在欧洲、美洲和亚洲，由于干旱和高温胁迫，橡树物种范围扩大，因此，橡树物种通常被认为是抗旱的。蒙古栎（Quercus mongolicaFisch.）研究了树木生长速率和抗旱性在沿着水分梯度上的变化。在这项研究中，我们使用了一个网络的蒙古栎树轮样本在华北地区的水分梯度范围很广，以评估橡树生长及其对干旱在不同的水分条件下的反应。研究结果表明，树木径向生长速率的空间变异与区域的水分指数高度相关，水分指数是指示水分状况的指标。橡树在干燥的部分比那些在潮湿的部分，他们的生长更敏感的干旱事件。我们使用大气环流模型的气候预测集合来预测伊万诺夫水分指数的未来变化，然后估计2021-2100年期间的树木生长率和干旱生长相关性。增加干燥可能会显着降低树木的平均生长速度，并增加干旱的敏感性径向生长在我们的研究区域不断扩大的干燥部分，导致大量的整体干旱抑制生长。我们的研究结果表明，干燥将对蒙古栎在中国北方已经干燥的地区的持续扩张提出越来越大的挑战，而橡树在高水分条件下会更好地茁壮成长。蒙古栎树的分布可能会转移到水分供应增加的地区，特别是在干旱加剧的情况下。
Mongolian oak is a widely distributed tree species in broadleaf forests of North China, which are susceptible to increasing drought. Expansion of oak species ranges has been reported in Europe, America, and Asia with drought and heat stress, and thus, oak species are often deemed to be drought-resistant. As an expanding species in our study region, the Mongolian oak (Quercus mongolicaFisch. ex Ledeb) was used to investigate how tree growth rate and drought resistance change along a moisture gradient. In this study, we used a network of Mongolian oak tree-ring samples across a wide range of moisture gradients in North China to assess oak tree growth and its response to drought under different moisture conditions. Our results revealed that spatial variation in tree radial growth rate was highly related to the regions’ moisture index, an index indicating moisture condition. Oak trees in drier portions grew slower than those in wetter portions and their growth was more sensitive to drought events. We used an ensemble of climate projections from general circulation models to predict future changes in the Ivanov moisture index, and then estimated the tree growth rate and drought-growth correlation for the period 2021–2100. Increased dryness is likely to reduce tree average growth rate markedly and increase the drought sensitivity of radial growth in the expanding dry portions of our study region, leading to substantial overall drought suppression of growth. Our results suggest that dryness will present an increasing challenge for the continuing expansion of Mongolia oak in already dry areas of North China, whereas oak trees will thrive better in high moisture conditions. The distribution of Mongolia oak trees will likely shift to regions with increased moisture availability, especially under the increasing drought.