Defoliation increased above-ground productivity in a semi-arid grassland
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Authors: M. R. Loeser, T. E. Crews, and T. D. Sisk
Date: 2004
Journal: Rangeland Ecology & Management
Volume: 57
Number: 5
Pages: 442-447
Summary of Methods: The effects of defoliation in ungrazed, recently grazed, and long-term grazed high elevation grasslands were determined in this study. A single early season defoliation enhanced above-ground production, however, the increased production was composed mainly of squirreltail (Elymus elymoides). A history of defoliation, for one or several growing seasons before clipping, reduced the compensatory response in above-ground production but plant production was still greater in these plots than in undefoliated plots. These results indicate that grazing can enhance plant production in this high elevation grassland but that grazing history can impact the magnitude of the plant community's response and therefore the authors suggest that more research is required to determine how these grasslands will respond to repeated defoliation within and among years before grazing recommendations can be made.
Article Summary / Main Points: None
Vegetation Types:
MLRA Ecoregions:
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: high-elevation grasslands, above-ground net primary production (anpp), overcompensation, root biomass, western wheatgrass, pascopyrum smithii, squirreltail, elymus elymoides
Annotation: In 1997, three, 1-ha exclosures were built in a 325-ha pasture that had been grazed by cattle in varying densities. Each exclosure was paired with a 1-ha enclosure that annually received a very high impact grazing treatment with an average stocking density of 200 cow/calf pairs/ha for 8 hours per year. ,In the livestock exclosures, each experimental plot included four, 1-m2 subplots. In May 2000, one subplot was defoliated to a height of 2.5-cm and 2 subplots were harvested at the end of the growing season.
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