Submitted to: Society for Range Management Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/13/1998
Publication Date: N/A
Technical Abstract: Changes in vegetation composition have been documented throughout the southwestern United States over the course of the last century. Many grasslands in southeastern Arizona have been invaded by exotics such as Lehmann lovegrass (Eragrostis lehmanniana) and woody shrubs such as mesquite (Prosopis velutina and P. glandulosa). Such changes are of particular concern to land managers because plant community determines a site's value for watershed protection, recreation, wildlife habitat, and livestock grazing. Land management objectives such as productivity and conservation require knowledge of both historic and current vegetation on any given site. In the summer of 1967, 110 permanent vegetation transects were established at 55 rain gages on the Walnut Gulch Experimental Watershed in southeastern Arizona. Data collected in 1967, 1994, 1995 and 1996 at these transects were analyzed and compared. Changes in plant canopy cover, composition, species richness, spatial distribution, and range site condition occurred at many of the sites over the period of study. Possible contributing mechanisms for vegetation change, including land use history, fire history, and long-term climatic changes were investigated.