Water Economy of Neo-Tropical Savanna Ecosystems: The Impact of Hydraulic Lift, Partitioning of Soil Water and Changes in Land Use

戈德斯坦新热带稀树草原生态系统的水经济：水力抬升、土壤水分分配和土地利用变化的影响通过水力将水从深层土壤提升到可能限制水分的浅层土壤，直接影响土壤剖面中水分的分布和有效性。水力提升可以对干燥的热带稀树草原的水循环产生重大影响，因为深深扎根的树木可以将水提升到草本植物扎根的地表1米以内。目前的土地利用做法正在减少巴西稀树草原的树木丰富度，这是南美洲仅次于热带雨林的第二大生态系统。移除树木，以及相关的水力提升能力的降低，可能会导致生态系统再循环过程中土壤深层水分和养分的大量流失。这项研究将描述巴西稀树草原的水分调节特征，并评估水力提升对土壤水分分布、总蒸散量和木本植物和草本植物用水量分配的影响。这项研究的结果将对木本植物和草本植物之间相互作用的性质以及热带稀树草原生态系统当前土地管理做法的后果提供新的见解。

Abstract00-75235GoldsteinWater economy of neo-tropical savanna ecosystems: The impact of hydraulic lift, partitioning of soil water and changes in land useRoots can directly affect the distribution and availability of water in the soil profile by hydraulically lifting water from deep soil layers to shallow soil layers where water may be limiting. Hydraulic lift can have a significant impact on the water cycle of dry tropical savannas, because deeply rooted trees can lift water to within 1 m of the surface where herbaceous plants are rooted. Current land-use practices are reducing the abundance of trees in Brazilian savannas, the second most extensive ecosystem in South America after the rain forests. Tree removal, and the associated reduction in hydraulic lift, may result in a substantial fraction of the deep soil water and nutrients being lost from ecosystem recirculation processes. This study will characterize the regulation of water in Brazilian savannas and evaluate the impact of hydraulic lift on the distribution of water in the soil, on total evapotranspiration and on partitioning of water consumption among woody and herbaceous plants. The results of this study will provide new insights on the nature of interactions between woody and herbaceous plants and on the consequences of current land management practices in tropical savanna ecosystems.