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首页> 外文期刊>Agricultural and Forest Meteorology >Evaluating climatic and soil water controls on evapotranspiration at two Amazonian rainforest sites
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Evaluating climatic and soil water controls on evapotranspiration at two Amazonian rainforest sites

机译：评价两个亚马逊雨林站点的蒸散量的气候和土壤水控制

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Interactions between the biosphere and the atmosphere have profound impacts on the functioning of the Earth system. One of the most important areas of biosphere-atmosphere interaction is the Amazon basin, which plays a key role in the global cycles of carbon, water and energy. The Amazon is vulnerable to climatic change, with increasingly hot and dry conditions expected over the next 50-100 years in some models. The resulting loss of carbon from the Amazon basin has been suggested as a potentially large positive feedback in the climate systemd. We investigated the differences in atmospheric demand and soil water availability between two sites; Manaus, in central Amazonia, where evapotranspiration was limited in the dry season, and Caxiuana in eastern Amazonia, where it was not. New soil hydraulic data including water release and unsaturated hydraulic conductivity curves were collected at Caxiauna using the instantaneous profile method (IPM), pressure plate analysis and tension infiltrometry. These data were compared to existing data from Manaus. The plant available soil water at the Caxiuana site was 2.1-3.4 times larger than the Manaus site. The hydraulic conductivity curves indicated the existence of a secondary macropore structure at very low tensions (-0.05kPa to -1kPa), potentially caused by biogenic macropores, but did not vary with respect to soil water potential between sites. In addition, differences in the climatic severity of the dry season were estimated. The maximum soil water deficit, projected using a simple model of forest water use, was similar between the sites. No difference in climatic severity between sites was found and we conclude that below-ground supply of water, rather than climatic differences, were likely to have caused the contrasting dry season behaviour at the two sites. These findings indicate that, in combination with other factors, heterogeneity in soil water retention capacity may exert strong controls on the spatial variation in forest responses to climatic change.
机译：生物圈与大气之间的相互作用对地球系统的功能产生了深远的影响。生物圈与大气相互作用最重要的领域之一是亚马逊盆地，它在全球碳，水和能源循环中起着关键作用。亚马逊很容易受到气候变化的影响，某些型号的亚马逊在未来50至100年的干热状况预计会越来越多。有人建议将亚马逊流域的碳损失作为系统气候中潜在的大量积极反馈。我们调查了两个地点之间的大气需求和土壤水分供应的差异;亚马逊河中部的马瑙斯在干旱季节的蒸散量有限，而亚马逊河东部的卡修亚纳则没有。使用瞬时剖面法（IPM），压力板分析和张力渗透法，在卡夏纳纳收集了新的土壤水力数据，包括水分释放和不饱和水力传导率曲线。将这些数据与Manaus的现有数据进行了比较。 Caxiuana场地的植物有效土壤水分是Manaus场地的2.1-3.4倍。水力传导率曲线表明，在很低的张力（-0.05kPa至-1kPa）下存在二级大孔结构，可能是由生物大孔引起的，但相对于位点之间的土壤水势没有变化。此外，估计了旱季气候严重程度的差异。用一个简单的森林用水模型预测的最大土壤水分亏缺在两个地点之间是相似的。没有发现站点之间气候严重程度的差异，我们得出的结论是，地下供水而不是气候差异可能导致了两个站点干旱季节行为的对比。这些发现表明，结合其他因素，土壤保水能力的异质性可以对森林对气候变化的响应的空间变化施加强有力的控制。

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