Drought tolerance and water use by plants along an alpine topographic gradient
Drought tolerance and water use by plants along an alpine topographic gradient
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DOI：
10.1007/bf00344971
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发表时间：
1981-09
期刊：
影响因子：
2.7
通讯作者：
S. Oberbauer;W. D. Billings
中科院分区：
文献类型：
--
作者：
S. Oberbauer;W. D. Billings
在北美西部山区的高山地带，地形湿度梯度是冬季风将雪从迎风坡和山脊上吹到背风坡的雪堆中的结果。背风坡脚下潮湿的草地是夏季融雪的结果。这样的梯度在一个山脉中重复多次。它们是研究干旱和水分利用对高山植被格局影响的有用单元。这项研究是在怀俄明州的梅迪辛博山脉沿沿着3,300米的地形梯度进行的。植物水势测定29种（黎明前到日落），每周一次。同时，叶电导测定16种这些，其余的叶子太小的气孔计。叶水势一般最低的山脊和最高的湿草甸。最高的平均叶电导在潮湿的草甸植物，最低的发生在植物上迎风坡。山脊上的植物没有一棵的叶子大到可以让气孔计测量。大多数物种的植物在所有网站，但潮湿的草甸表现出急剧下降的叶导或叶死亡，植物水势低于-1.5 MPa。深根植物如三叶草表现出最大的电导率在低至-1.7 MPa的水势和电导率几乎没有减少，即使在较低的水势。植株水势和叶片导度与生根深度、干旱期长短和坡位关系密切。
In the alpine zones of western North American mountains, topographic-moisture gradients are the results of winter winds blowing snow from the upper windward slopes and ridgetops into snowdrifts on the lee slopes. Wet meadows at the foot of the lee slope are the result of summer snowmelt. Such gradients are repeated many times in a single mountain range. They are useful units for studies of the effects of drought and water use on patterning of alpine vegetation.The research was done through an entire growing season along a topographic gradient at 3,300 m in the Medicine Bow Mountains, Wyoming. Plant water potentials were measured on 29 species (pre-dawn to sunset) at weekly intervals. Simultaneously, leaf conductances were measured on 16 species of these; the remainder had leaves too small for the porometer. Leaf water potentials were generally lowest on the ridgetop and highest in the wet meadow. Highest mean leaf conductances were in the wet meadow plants; the lowest occurred on plants on the upper windward slope. None of the plants on the ridgetop had leaves large enough for the porometer. Plants of most species at all sites but the wet meadow showed sharply reduced leaf conductance or leaf death at plant water potentials below-1.5 MPa. Deep-rooted species such asTrifolium parryishowed maximal conductance at water potentials as low as-1.7 MPa and little reduction in conductance even at lower water potentials. Plant water potentials and leaf conductances showed close relationships with rooting depth, length of dry periods, and position on the gradient.