Short-term response of riparian vegetation to 4 grazing treatments.

Abstract

The Sheep Creek watershed of northcentral Colorado provided an ideal site to collect baseline trend data and to estimate foliar cover responses of montane riparian vegetation. Percent relative cover data were compared with Sorensen's similarity index and were analyzed with a 2-stage nested analysis of variance (ANOVA) to assess differences among 4 grazing treatments: long-term grazing (G), protection from livestock grazing since 1956 (P), recent protection following long-term grazing (P88), and recent livestock grazing following protection (G88). This study utilized 3 replications of each treatment. Data were collected in August 1988, June 1989, and August 1989, employing permanent and randomly placed transects and plots. When percent foliar cover means were paired using Sorensen's similarity index, long-term grazing and short-term grazing treatments were least similar in August 1988. Long-term protection and short-term grazing were most similar in June 1989. Average percent cover of bare ground, common dandelion (Taraxacum officinale Wiggers), white Dutch clover (Trifolium repens L.), and legumes grouped as lifeforms were significantly different among treatments, with long-term grazing being significantly different from long-term protection. Average sedge and forb cover was least affected. However, responses of individual sedge species varied with treatments. Average percent grass cover increased under short-term protection after a history of long-term grazing. Short-term grazing stimulated foliar cover of forbs, grasses, and sedges after more than 30 years of cattle exclusion.