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Northern Arizona University (2001)

Plant and insect community responses to livestock grazing in arid and semi-arid grasslands

Loeser Matthew Robert

Titre : Plant and insect community responses to livestock grazing in arid and semi-arid grasslands

Auteur : Matthew Robert Loeser

Université de soutenance : Northern Arizona University

Grade : Master of Science (MS) 2001

Résumé
One of the most prevalent land-use practices in the American Southwest, and one of the most contentious issues among land-use policymakers, is the grazing of domestic livestock. In an effort to contribute scientific understanding to this debate, we have designed experiments comparing the effects of alternative grazing regimes on plant communities. In a semiarid grassland of northern Arizona, we have implemented a replicated study of four treatments : (1) low-intensity, long-duration grazing rotations ; (2) high-intensity, short-duration rotations (Holistic Resource Management-style grazing) ; (3) very high intensity, short duration grazing (to simulate herd impact) ; and (4) livestock exclosure. Beginning in 1997, we conducted annual surveys of the plant communities with Modified-Whittaker plots. Preliminary results suggest that interannual variability affecting all study plots is high, and that these alternative management strategies do not have dramatic short-term effects on the plant community. Comparisons of native and exotic species richness, as well as ground cover of grasses and forbs, showed no consistent pattern due to treatment over a 3-year period. Our results suggest that the effects of alternative livestock management styles in the semiarid grasslands studied are modest, at least in the short-term, and that future plant monitoring programs would greatly benefit from a multiscale sampling design.

Annonce

Page publiée le 27 janvier 2012, mise à jour le 9 septembre 2018