Tree responses to moisture fluctuations in a neotropical dry forest as potential climate change indicators
Tree responses to moisture fluctuations in a neotropical dry forest as potential climate change indicators
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DOI：
10.1016/j.ecolind.2016.11.021
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发表时间：
2017-12-01
影响因子：
6.9
通讯作者：
Braeuning, Achim
中科院分区：
文献类型：
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作者：
Butz, Philipp;Raffelsbauer, Volker;Braeuning, Achim
热带干燥森林中的树木有多种干旱应对策略，包括不同植物器官的肉质化、木材解剖特征和叶片物候。由于植物的水分供应是生理活动的限制因素，降水模式的变化被认为对树木的物候、生长和水分周转有很大的影响。我们的目标是评估叶物候、径向茎周长变化和汁液通量对选定物种水分波动的响应模式。基于这些发现，我们评估了作为气候变化影响指示物种的潜在适宜性。这项研究是在厄瓜多尔南部山下干燥森林的不同海拔位置进行的。年降雨量为600毫米，有8个月的干旱期；由于来自太平洋的潮湿空气，湿度可获得性随着海拔的升高而略有增加。在三个海拔高度，我们研究了树种Ceiba trichiStandra(叶落叶，茎肉质)，Erio theca ruizii(叶落叶，根肉质)和Erythina velutina(叶落叶)。在整个研究期间和在海拔梯度的所有位置，都观察到了这三个物种可逆的茎膨胀和收缩。然而，在肉质三叉树的茎和最低(最干燥)的位置上，它是最明显和敏感的。三枝黄柏在旱季出现间歇性雨冲叶，从旱季到湿季出叶较早，这一时期树干液流较高，树干周长减小。各树种的叶期长度均随海拔的升高而增加。因此，物种、地形位置、径向生长和树木水分利用模式之间存在着明显的差异，特别是三叉树对水分变化非常敏感，叶物候、树干液流和树干直径的变化，可以作为评估气候变化的敏感指标。(C)2016爱思唯尔有限公司。保留所有权利。
Trees in tropical dry forests (TDFs) have manifold drought coping strategies including succulence of different plant organs, wood anatomical traits and leaf phenology. As water availability to plants is the limiting factor for physiological activity; changes in precipitation patterns are assumed to have strong influences on tree phenology, growth and water turnover. Our objectives were to assess patterns in leaf phenology, radial stem circumference changes and sap flux responses to fluctuating moisture regimes of selected species. Based on these findings we evaluated the potential suitability as indicator species for climate change effects. The study was implemented at different elevational positions in a submontane dry forest of southern Ecuador. Annual rainfall is 600 mm with an eight months dry period; moisture availability slightly increases with altitude because of moist air coming from the Pacific. At three altitudes, we studied the tree species Ceiba trichistandra (leaf deciduous, stem succulent), Erio theca ruizii (leaf deciduous, root succulent) and Erythrina velutina (leaf deciduous). Reversible stem swelling and shrinking was observed for all three species during the whole study period and at all positions at the altitudinal gradient. However, it was most pronounced and sensitive in the stem succulent C. trichistandra and at the lowest (driest) position. C. trichistandra flushed leaves at dry season intermittent rain events, and from dry to wet season leaf out was earlier, and in this period sap flux was high while stem circumference decreased. Length of the leaved periods of all species increased with altitude. Thus, clear differences among species, topographic positions, radial growth and tree water use patterns are revealed; especially C. trichistandra responded very sensitive to fluctuating moisture regimes with leaf phenology, sap flux and stem diameter variations, and can be regarded as a sensitive indicator for assessing climatic variations. (C) 2016 Elsevier Ltd. All rights reserved.