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首页> 外文期刊>Plant and Soil >Vertical patterns of soil water uptake by plants in a primary forest andan abandoned pasture in the eastern Amazon: an isotopic approach
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Vertical patterns of soil water uptake by plants in a primary forest andan abandoned pasture in the eastern Amazon: an isotopic approach

机译：亚马逊东部原始森林和废弃牧场中植物对土壤水分吸收的垂直模式：一种同位素方法

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This study evaluated the water uptake patterns of a primary forest and of the savanna-like vegetation of an abandoned pasture in an eastern Amazon site. We used natural stable isotope abundance in the soil profile, as well as plots irrigated with deuterated water to determine time and depth of soil water uptake by plants in different functional groups. Natural isotopic abundance was not suitable for identification of depth of water uptake by plants, but experiments using labeled water were. We found that the label percolation rate in the soil profile of the forest was lower than that observed in the pasture. Fourteen months after application, the label peak was located at 1.8 m depth in the forest and at 3 m depth in the pasture. Isotopic analysis of sap water from trees and lianas in the forest during the dry season showed that trees acquired labeled water at a deeper level in the soil profile compared to that acquired by lianas. Depth of water uptake by lianas seems to vary on a seasonal basis. In the pasture the 'colonizer' shrub (Solanum crinitum Lamb.) took up labeled water only from the surface layer of the soil profile (similar to 20%), whereas the most abundant coexisting grass (Panicum maximum Jacq.) acquired it from the top meter. None of the pasture plants were able to acquire labeled water after one rainy season when the label pulse was deep in the soil (> 1 m deep). These results have implications for studies of forest water cycle in which the soil volume used as source of water for plant transpiration is still unknown, and for an understanding of plant succession in the forest regeneration process of abandoned pastures in the eastern Amazon.
机译：这项研究评估了亚马逊东部地区一个原始森林和一个废弃牧场的热带稀树草原植被的吸水模式。我们在土壤剖面中使用了自然稳定的同位素丰度，以及使用氘化水灌溉的地块，以确定不同功能组中植物吸收土壤水的时间和深度。天然同位素丰度不适合识别植物对水的吸收深度，但使用标记水的实验却适用。我们发现森林土壤剖面中的标签渗透率低于牧场中观察到的渗透率。施药后14个月，标签峰位于森林中1.8 m的深度和牧场中3 m的深度。干旱季节从森林中树木和藤本植物的树汁水的同位素分析表明，与藤本植物相比，树木在土壤剖面中获取的标记水含量更高。藤本植物的吸水深度似乎随季节而变化。在牧场中，“定殖剂”灌木（Solanum crinitum Lamb。）仅从土壤剖面的表层（约占20％）吸收带标签的水，而最丰富的共存草（Panicum maximum Jacq。）则从土壤中获取。最高的仪表。在一个雨季之后，当标签脉冲在土壤深处（> 1 m深）时，没有一家牧场植物能够获得标签水。这些结果对森林水循环的研究具有重要意义，在森林水循环中，用作植物蒸腾水的土壤量仍然未知，并且对于在亚马逊东部废弃牧场的森林更新过程中了解植物演替也有一定的意义。

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