Changes in leaf functional traits of rainforest canopy trees associated with an El Niño event in Borneo
Changes in leaf functional traits of rainforest canopy trees associated with an El Niño event in Borneo
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与婆罗洲厄尔尼诺事件相关的雨林冠层树木叶子功能特征的变化
DOI：
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发表时间：
2019
影响因子：
6.7
通讯作者：
Mark Cutler
中科院分区：
文献类型：
--
作者：
Matheus Henrique Nunes;Sabine Both;Boris Bongalov;Craig C. Brelsford;Sacha Khoury;D. Burslem;Christopher D. Philipson;N. Majalap;T. Riutta;David A. Coomes;Mark Cutler
厄尔尼诺事件在东南亚热带雨林造成相对较低的降水量、低云量和高温，但其对树木生理的影响仍然知之甚少。在这里，我们使用遥感和功能性状的方法，通常用于了解植物适应环境波动，以评估热带雨林的厄尔尼诺事件在北方婆罗洲的一个网站的反应。星载测量（即根据中分辨率成像光谱仪数据计算的归一化差异植被指数）显示，整个2015年，雨林树冠变绿，与马来西亚沙巴厄尔尼诺事件的加强相吻合，然后在2016年初厄尔尼诺达到顶峰时失去绿色。在厄尔尼诺事件期间和之后，对65个物种（来自99个树冠的104个分支）的成熟叶片进行了叶片化学和结构特征测量，结果显示，2015年中期的叶绿素和类胡萝卜素浓度比2016年中期高出35%。营养素N，P，K和Mg的叶片浓度没有变化，表明矿化和运输过程不受厄尔尼诺事件的影响。叶含有更多的酚类物质，单宁和纤维素，但较少的钙和木质素在厄尔尼诺事件，与浓度变化强烈的物种之间的差异。这些功能性状的变化也很明显，在高光谱反射率数据收集使用现场光谱仪，特别是在短波红外区域。叶片水平的驯化和叶片周转可能驱动观察到的性状变化。我们认为，在厄尔尼诺事件的初始阶段，树木并没有受到水的限制，并通过冲洗新叶来做出反应，这可以从树冠绿化趋势和较高的色素浓度（与嫩叶相关）中看出;我们认为，高蒸发需求和土壤水分耗尽最终导致2016年树叶下降。然而，需要进一步的研究来证实这些想法。只有在地面上监测功能特征的变化以及冠层中树叶数量的变化，才能理解从空间获得的植被动态的时间序列。
El Niño events generate periods of relatively low precipitation, low cloud cover and high temperature over the rainforests of Southeast Asia, but their impact on tree physiology remains poorly understood. Here we use remote sensing and functional trait approaches—commonly used to understand plant acclimation to environmental fluctuations—to evaluate rainforest responses to an El Niño event at a site in northern Borneo. Spaceborne measurements (i.e. normalised difference vegetation index calculated from Moderate Resolution Imaging Spectroradiometer data) show the rainforest canopy greened throughout 2015, coinciding with a strengthening of the El Niño event in Sabah, Malaysia, then lost greenness in early 2016, when the El Niño was at its peak. Leaf chemical and structural traits measured for mature leaves of 65 species (104 branches from 99 tree canopies), during and after this El Niño event revealed that chlorophyll and carotenoid concentrations were 35% higher in mid 2015 than in mid 2016. Foliar concentrations of the nutrients N, P, K and Mg did not vary, suggesting the mineralisation and transportation processes were unaffected by the El Niño event. Leaves contained more phenolics, tannins and cellulose but less Ca and lignin during the El Niño event, with concentration shifts varying strongly among species. These changes in functional traits were also apparent in hyperspectral reflectance data collected using a field spectrometer, particularly in the shortwave infrared region. Leaf-level acclimation and leaf turnover could have driven the trait changes observed. We argue that trees were not water limited in the initial phase of the El Niño event, and responded by flushing new leaves, seen in the canopy greening trend and higher pigment concentrations (associated with young leaves); we argue that high evaporative demand and depleted soil water eventually caused leaves to drop in 2016. However, further studies are needed to confirm these ideas. Time-series of vegetation dynamics obtained from space can only be understood if changes in functional traits, as well as the quantity of leaves in canopies, are monitored on the ground.
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DOI：
10.1002/2017jg003883
发表时间：
2017-11
期刊：
Journal of Geophysical Research: Biogeosciences
影响因子：
--
作者：
C. Doughty;P. Santos-Andrade;G. Goldsmith;B. Blonder;A. Shenkin;L. Bentley;C. Chavana-Bryant;
通讯作者：
C. Doughty;P. Santos-Andrade;G. Goldsmith;B. Blonder;A. Shenkin;L. Bentley;C. Chavana-Bryant;
影响因子：
9.4
作者：
Chavana-Bryant, Cecilia;Malhi, Yadvinder;Gerard, France F.
通讯作者：
Gerard, France F.
DOI：
10.1073/pnas.0505734102
发表时间：
2005-10-18
影响因子：
11.1
作者：
Breshears, DD;Cobb, NS;Meyer, CW
通讯作者：
Meyer, CW
影响因子：
64.8
作者：
Doughty, Christopher E.;Metcalfe, D. B.;Malhi, Y.
通讯作者：
Malhi, Y.