STREAMSIDE TREES THAT DO NOT USE STREAM WATER
STREAMSIDE TREES THAT DO NOT USE STREAM WATER
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DOI：
10.1038/350335a0
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发表时间：
1991-03-28
期刊：
影响因子：
64.8
通讯作者：
EHLERINGER, JR
中科院分区：
文献类型：
--
作者：
DAWSON, TE;EHLERINGER, JR
一个长期存在的公理是植物分布受土壤含水量的强烈影响1,2。虽然有研究表明，生活在河边群落的植物类群接受或使用了更多的水，但人们假设这些水是从它们生长的地方附近的溪流中获得的。在这里，我们表明，使用自然丰度水平的氢同位素比率分析，生长在多年生河流中或紧邻河流的成熟的河边树木很少或根本不使用地表水。源水和木质部水的氘氢比表明成熟树木利用的是较深层的水。虽然成树的根可能连续分布在整个土壤剖面上，但吸水最活跃的部位似乎仅限于较深的土层。相反，小的溪侧个体似乎以溪流水为主要水源，而小的非溪侧个体则以近期降水为主要水源。我们的分析既提供了一种相对非破坏性的评估植物水源的方法，也提供了一种评估共生类群之间潜在竞争相互作用的方法。此外，该方法可能有助于解决水在确定土壤湿度梯度明显的地区植物分布中的作用。
A LONG-STANDING axiom is that plant distribution is strongly influence by soil moisture content 1, 2. While it has been shown that plant taxa inhabiting streamside communities receive or use more water 3, it is assumed that this water is obtained from the stream adjacent to where they are found growing. Here we show, using hydrogen isotope ratio analyses at natural abundance levels, that mature streamside trees growing in or directly next to a perennial stream used little or none of the surface stream water. The deuterium to hydrogen content of both source and xylem waters indicated that mature trees were using waters from deeper strata. Although adult trees may have roots distributed continuously throughout a soil profile, it seemed that the most active sites of water absorption were limited to deeper soil layers. In contrast, small streamside individuals appeared to use stream water, whereas small non-streamside individuals used recent precipitation as their primary water source. Our analyses provide both a relatively non-destructive method for assessing water sources of plants and a means of assessing potential competitive interactions among co-occurring taxa. In addition, the method may aid in resolving the role of water in determining plant distributions in areas characterized by sharp soil moisture gradients.