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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #168146
Title: ECOLOGICAL SIGNIFICANCE OF DROUGHT RESISTANCE IN PSEUDOROEGNERIA SPICATA AND ELYMUS ELYMOIDES

Author
item THYGERSON, TONYA - UTAH STATE UNIV.
item Monaco, Thomas

Submitted to: Society of Range Management
Publication Type: Abstract Only
Publication Acceptance Date: 2/5/2005
Publication Date: 2/5/2005
Citation: Thygerson, T., Monaco, T.A. 2005. Ecological significance of drought resistance in pseudoroegneria spicata and elymus elymoides. Society of Range Management.

Interpretive Summary:

Technical Abstract: The physiological mechanisms of plants to overcome drought are primarily evaluated at the plant level. However, the ecological significance of these mechanisms are poorly understood at the community level. We conducted a field experiment in a rainout shelter to identify the magnitude of intra-and interspecific variation in drought resistance mechanisms of Elymus elymoides and Pseudoroegneria spicata populations from 4 distinct ecosystems in the Western U.S. Initial results show that water limitation decreased photosynthesis, leaf transpiration, and quantum yield of PSII in all populations of both species. Populations of both species from the Wasatch ecosystem had greater photosynthesis; whereas, E. elymoides from the Great Basin and P. spicata from the Palouse prairie maintained low photosynthesis during the season. Under favorable water supply, stomatal conductance of all E. elymoides populations increased during the season. On the contrary, stomatal conductance for P. spicata populations increased until early June, then declined afterward. Consequently, these results suggest that populations of both species from divergent ecosystems show surprising similarity in their physiological responses to drought. We anticipate that a closer look at the relationship between the relative expressions of drought avoidance and tolerance mechanisms and their association with the ability to cope with defoliation and compete for limiting soil nitrogen may help explain these similarities.