Recovery of Alpine Vegetation on Small, Denuded Plots, Niwot Ridge, Colorado, U.S.A.

Abstract

Small plots (0.25 to 1.0 m2) denuded 13 and 31 yr previously were studied to investigate vegetation recovery at the alpine site of the Long-Term Ecological Research network. Recovery was slow, probably due to poor seedling survival. Covers of vascular plants and lichens were much lower on denuded plots than on controls except in late-melting snowbanks where natural disturbance by pocket gophers may have selected for disturbance-adapted species. Moister communities generally regained cover faster than drier communities. Vegetative expansion from plot edges provided most cover, although some colonizers originated from seed. Kobresia myosuroides, previously unknown to reproduce sexually in the Southern Rocky Mountains, occasionally colonized by seed. Essentially all vascular species acted as both colonizers and components of mature vegetation, and the vast majority of species are present in similar relative frequencies in control and disturbed plots. Previously studied alpine sites show either a similar lack of differentiation of early- and late-successional species or higher relative abundance of grasses in disturbed sites. In contrast to vegetation recovery in most temperate ecosystems, in these small plots on Niwot Ridge sequential replacement of species after disturbance does not occur.