Impact of grazing intensity during drought in an Arizona grassland: Contributed papers

Matthew R R Loeser, Thomas D Sisk, Timothy E. Crews

Research output: Contribution to journalArticle

58 Citations (Scopus)

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.

Original languageEnglish (US)
Pages (from-to)87-97
Number of pages11
JournalConservation Biology
Volume21
Issue number1
DOIs
StatePublished - Feb 2007

Fingerprint

grazing intensity
Drought
grazing
grasslands
grassland
drought
cattle
Conservation
Bromus tectorum
annual plant
ground cover plants
rangeland
rangelands
Chemical analysis
community response
botanical composition
Western United States
plant community
plant communities
experimental study

Keywords

  • Bromus tectorum
  • Cheatgrass
  • Climatic variation
  • Exotic plants
  • Livestock grazing
  • Plant community
  • Plant cover
  • Short duration grazing

ASJC Scopus subject areas

  • Ecology
  • Environmental Science(all)
  • Environmental Chemistry
  • Nature and Landscape Conservation

Cite this

Impact of grazing intensity during drought in an Arizona grassland : Contributed papers. / Loeser, Matthew R R; Sisk, Thomas D; Crews, Timothy E.

In: Conservation Biology, Vol. 21, No. 1, 02.2007, p. 87-97.

Research output: Contribution to journalArticle

Loeser, Matthew R R ; Sisk, Thomas D ; Crews, Timothy E. / Impact of grazing intensity during drought in an Arizona grassland : Contributed papers. In: Conservation Biology. 2007 ; Vol. 21, No. 1. pp. 87-97.
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