In this Colorado study, Coffin and Lauenroth evaluate the effects of interactions among disturbance characteristics on the successional dynamics of small scale disturbances in shortgrass steppe plant communities, by comparing naturally occurring and artificially produced disturbances of different type, seasonality, size, and location by soil texture. The species composition on the two naturally occurring disturbances (western harvester ant (Pogonomyrex occidentalis) mounds and small animal burrows) were similar one year after plant recovery began, but were different from the composition on the artificially produced disturbances. The recolonization of western harvester ant mounds was primarily by perennials, and the density of annuals on the mounds was greater than on animal burrows and most artificial plots. Bouteloua gracilis was not found in significant amounts on ant mounds or artificial plots. In contrast to ant mounds and animal burrows, the majority of the cover on the artificially produced disturbances for the site, with coarse and fine textured soils, and most date and sizes, was attributed to annuals. Although annuals and perennials responded similarly to the effects of recolonization date, they responded differently to disturbance size. The cover and density of the most important perennial forb on the plots, Sphaeralcea coccinea, were highest in the center of the largest plots, or the farthest distance from potential competitive interactions with plants in the surrounding undisturbed community. These results suggest that animal burrows will have the most rapid recovery time of the disturbance types studied and the largest artificially produced plots will have the slowest recovery time.
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