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Titre du document / Document title

Impact of grazing intensity during drought in an arizona grassland

Auteur(s) / Author(s)

LOESER Matthew R. R. (1 2) ; SISK Thomas D. (1) ; CREWS Timothy E. (2) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Center for Environmental Sciences and Education, Northern Arizona University, Box 5694, Flagstaff, AZ 86011-5694, ETATS-UNIS
(2) Environmental Studies Program, Prescott College, 220 Grove Avenue, Prescott, AZ 86301, ETATS-UNIS

Résumé / Abstract

The ecological benefits of changing cattle grazing practices in the western United States remain controversial, due in part to a lack of experimentation. In 1997 we initiated an experimental study of two rangeland alternatives, cattle removal and high-impact grazing, and compared grassland community responses with those with more conventional, moderate grazing practices. The study was conducted in a high-elevation, semiarid grassland near Flagstaff, Arizona (U.S.A.). We conducted annual plant surveys of modified Whittaker plots for 8 years and examined plant composition shifts among treatments and years. High-impact grazing had strong directional effects that led to a decline in perennial forb cover and an increase in annual plants, particularly the exotic cheatgrass (Bromus tectorum L). A twofold increase in plant cover by exotic species followed a severe drought in the sixth year of the study, and this increase was greatest in the high-impact grazing plots, where native cover declined by one-half. Cattle removal resulted in little increase in native plant cover and reduced plant species richness relative to the moderate grazing control. Our results suggest that some intermediate level of cattle grazing may maintain greater levels of native plant diversity than the alternatives of cattle removal or high-density, short-duration grazing practices. Furthermore, episodic drought interacts with cattle grazing, leading to infrequent, but biologically important shifts in plant communities. Our results demonstrate the importance of climatic variation in determining ecological effects of grazing practices, and we recommend improving conservation efforts in arid rangelands by developing management plans that anticipate this variation.

Revue / Journal Title

Conservation biology    ISSN  0888-8892   CODEN CBIOEF 

Source / Source

2007, vol. 21, no1, pp. 87-97 [11 page(s) (article)] (1 p.1/4)

Langue / Language

Anglais

Editeur / Publisher

Wiley-Blackwell, Hoboken, NJ, ETATS-UNIS  (1987) (Revue)

Mots-clés anglais / English Keywords

Spermatophyta

;

Angiospermae

;

Monocotyledones

;

Gramineae

;

America

;

North America

;

United States

;

Bromus tectorum

;

Environmental protection

;

Duration

;

Plant cover

;

Plant community

;

Livestock

;

Plant introduction

;

Climatic condition

;

Climate

;

Grassland

;

Arizona

;

Drought

;

Browsing

;

Mots-clés français / French Keywords

Spermatophyta

;

Angiospermae

;

Monocotyledones

;

Gramineae

;

Amérique

;

Amérique du Nord

;

Etats Unis

;

Bromus tectorum

;

Protection environnement

;

Durée

;

Couvert végétal

;

Groupement végétal

;

Bétail

;

Introduction végétal

;

Condition climatique

;

Climat

;

Prairie

;

Arizona

;

Sécheresse

;

Broutage animal

;

Mots-clés espagnols / Spanish Keywords

Spermatophyta

;

Angiospermae

;

Monocotyledones

;

Gramineae

;

America

;

America del norte

;

Estados Unidos

;

Bromus tectorum

;

Protección medio ambiente

;

Duración

;

Cubierta vegetal

;

Comunidad vegetal

;

Ganado

;

Introducción vegetal

;

Condición climática

;

Clima

;

Pradera

;

Arizona

;

Sequedad

;

Pacedura

;

Mots-clés d'auteur / Author Keywords

Bromus tectorum

;

cheatgrass

;

climatic variation

;

exotic plants

;

livestock grazing

;

plant community

;

plant cover

;

short duration grazing

;

Localisation / Location

INIST-CNRS, Cote INIST : 21333, 35400014322573.0120

Nº notice refdoc (ud4) : 18522778



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