Meyer, Archie , Sage, Rowan , Skillman, John .
Microsite effects on Muhlenbergia richardsonis, A C4 grass growing in the alpine zone of California’s White Mountain range.
THE interactions of Muhlenbergia richardsonis, a presumably cold intolerant C4 grass, and its growing environment are fascinating as well as perplexing. We’ve documented this species to be growing above 13,000’ in the White Mountains of Eastern California. This alpine habitat is well out of the expected range for C4 plants. A field growth experiment was designed to examine microsite effects on plant growth and survivorship. Greenhouse cultivated M. richardsonis plants were planted out in 2004 on north or south slopes, in the presence or absence of rock sheltering at each of two elevations (10,000’ or 12,400’) in the White Mountains. During the 2005 growing season, air temperature, soil moisture, plant growth, and plant survivorship were assessed for each of these eight microsite treatments. Preliminary analyses indicate that these microsite treatments affected both air temperature and soil moisture. At each elevation, south facing plots tended to be warmer than north facing plots. Plots with rocks tended to be warmer than those without rocks. Across all eight microsite treatments, warmer plots tended to have drier soils than cooler plots. Indicators of ecological performance varied among the eight-microsite treatments in 2005. In particular, a strong liner association of soil moisture with both plant survivorship and growth indicates much of the variation in ecological performance can be explained by microclimatic variation. This important finding would suggest that M. richardsonis would have greater ecological success in cool, moist sites compared to warm, dry sites. This interpretation is surprising given the general expectation that C4 plants are drought tolerant but sensitive to low temperatures. Possible reasons for this unexpected finding will be discussed.
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1 - California State University San Bernadino, Biology Department, 5500 University Parkway, San Bernardino, California, 92407, USA
2 - University of Toronto, Department of Botany, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM