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Ecophysiology of Three C4 Perennial Grasses in the Northern Chihuahuan Desert
R. S. Senock, D. L. Devine, W. B. Sisson and G. B. Donart
The Southwestern Naturalist
Vol. 39, No. 2 (Jun., 1994), pp. 122-127
Published by: Southwestern Association of Naturalists
Stable URL: http://www.jstor.org/stable/3672235
Page Count: 6
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Despite changes in the relative abundance of C4 perennial grasses that have occurred in the northern portion of the Chihuahuan desert, no comparative physiological studies on these grasses have been reported. Concurrent measurements were made of leaf physiology, gas exchange, chlorophyll and nitrogen content for mature Bouteloua eriopoda, Sporobolus contractus, and Hilaria mutica during the spring period following an unusually long winter drought. Except for a brief period following rain, midday photosynthesis (A) in Bouteloua was below 10 μmol m-2s-1. Sporobolus also had low midday A early in the season but had the greatest increase in A following rain when rates approached 25 μmol m-2s-1 and maintained the higher rates through the subsequent dry period. In contrast to the other species, Hilaria exhibited higher A early in the season but a more moderate response to increased soil water. Results for the individual species are discussed in the context of speculations contained in published literature concerning varying degrees of drought resistance among the species. Future field studies on these grasses must be broader in scope to fully elucidate differences in drought resistance and the importance of any adaptive physiological mechanisms to past or present vegetation patterns.
The Southwestern Naturalist © 1994 Southwestern Association of Naturalists