How do rubber ( Hevea brasiliensis ) plantations behave under seasonal water stress in northeastern Thailand and central Cambodia
How do rubber ( Hevea brasiliensis ) plantations behave under seasonal water stress in northeastern Thailand and central Cambodia
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DOI：
10.1016/j.agrformet.2015.06.011
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发表时间：
2015-11
影响因子：
6.2
通讯作者：
T. Kumagai;R. G. Mudd;T. Giambelluca;N. Kobayashi;Y. Miyazawa;T. Lim;W. Liu;Maoyi Huang;J. Fox;A. Ziegler;S. Yin;S. Mak;P. Kasemsap
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文献类型：
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作者：
T. Kumagai;R. G. Mudd;T. Giambelluca;N. Kobayashi;Y. Miyazawa;T. Lim;W. Liu;Maoyi Huang;J. Fox;A. Ziegler;S. Yin;S. Mak;P. Kasemsap
研究了橡胶（Hevea brasiliensisMüll.）Arg.）人工林，这是迅速扩大整个大陆东南亚，是重要的了解土地利用变化对环境过程的影响。为了揭示橡胶转化的影响，我们在两个橡胶种植园进行了为期3年的涡流通量测量：（1）位于泰国东北部的Som Sanuk;（2）位于柬埔寨中部的柬埔寨橡胶研究所（CRRI）。这两个地方都有明显的旱季。我们使用的实际蒸散（ET）通量的测量和一个简单的2层ET模型的反演版本的组合估计平均冠层气孔导度（GS）。每个季节的潜在水平衡（降水量（P）-潜在蒸发量（ET_POT））（即，12月至2月：DJF，3月至5月：MAM，6月至8月：JJA，9月至11月：SON）揭示了何时以及如何控制用水。在实际水平衡（P-ET）为负值的季节（DJF和MAM），上一个季节0-2 m（泰国试验点）和0-3 m（柬埔寨试验点）深度的土壤水弥补了水分不足。在这两个地点，参考值的gs（gsref）和gs的敏感性，大气需求（m）似乎是在DJF和MAM比其他两个3个月的时期（季节）。平均而言，在一年中，泰国（<<0.6）的m/gsref小于柬埔寨（部分时间接近0.6），这表明泰国站点的气孔调节不足，由于其较高的年降雨量，水分胁迫引起的水力破坏的风险可能很小。相比之下，在CRRI annualP-ET_POT为负，有严格的气孔调节，防止过度木质部空化。
Delineating the characteristics of biosphere-atmosphere exchange in rubber (Hevea brasiliensisMüll. Arg.) plantations, which are rapidly expanding throughout mainland Southeast Asia, is important to understanding the impacts of the land-use change on environmental processes. In attempt to shed new light on the impacts of conversion to rubber, we have conducted eddy flux measurements over a 3-year period in two rubber plantation sites: (1) Som Sanuk, located in northeastern Thailand; and (2) Cambodian Rubber Research Institute (CRRI), located in central Cambodia. Both sites have a distinct dry season. We used a combination of actual evapotranspiration (ET) flux measurements and an inverted version of a simple 2-layerETmodel for estimating the mean canopy stomatal conductance (gs). The potential water balance (precipitation (P) − potential evaporation (ET_POT)) for each season (i.e., December–February: DJF, March–May: MAM, June–August: JJA, and September–November: SON) revealed when and how the water use is controlled. In the seasons when actual water balance (P − ET) was negative (DJF and MAM), the deficit was compensated with soil water from the previous season at depths of 0–2 m (Thailand site) and 0–3 m (Cambodia site). At both sites, the reference value ofgs(gsref) and the sensitivity ofgsto atmospheric demand (m) appeared to be less in DJF and MAM than each in the other two 3-month periods (seasons). On average, in a whole year,m/gsrefwas less in Thailand (<<0.6) than in Cambodia (near 0.6 for part of the year), suggesting that there was less sufficient stomatal regulation at the Thailand site, where there might be little risk of water stress-induced hydraulic failure because of its higher annual rainfall amount. In comparison, at CRRI where annualP−ET_POTwas negative, there was stricter stomatal regulation, preventing excessive xylem cavitation.