The effects of disturbance size and frequency on a shortgrass plant community
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Authors: D. P. Coffin, and W. K. Lauenroth
Date: 1988
Journal: Ecology
Volume: 69
Number: 5
Pages: 1609-1617
Summary of Methods: From field data collected in Colorado, Coffin and Lauenroth modeled the effects of three types of small patch-producing disturbances on a short-grass community, dominated by blue grama (Bouteloua gracilis). Disturbance included cattle fecal pats, western harvester ant mounds (Pogonomyex occidentalis), and small animal burrows. Ant mounds and animal burrows were significantly larger than blue grama plants, whereas fecal pats were comparable in size to blue grama plants. Frequency of disturbance occurrence was a good predictor of the amount of basal cover and the number of plants killed each year by each disturbance type. The fastest turnover types were associated with fecal pats, which were the smallest and most frequent form of disturbance. The effects of these disturbances were found to be dependent on grazing intensity, and especially topographic position. Slopes and lowlands had faster turnover rates than uplands. Results suggest that the recovery of blue grama is dependent on the spatial scale of the disturbance.
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: blue grama, bouteloua gracilis, animal burrows, ant mounds, disturbance frequency, disturbance size, gap turnover, grassland, grazing, patch dynamics, simulation model
Annotation: Since 1939, pastures have been managed under the following grazing intensities: light grazing = 1.4 ha/yearling/month (20% removal), moderate grazing = 1.1 ha/yearling/month (40% removal), heavy = 0.7 ha/yearling/month (60% removal). Season of use is not specified.
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