A comparative study of rangeland browse and forage within a pinyon-juniper ecosystem in Seligman, Arizona

Pinyon-juniper woodlands occupy tens of millions of acres across their North American range and have been increasing in size and density over the last century. Increase in size and density is due to several factors including overstocking of cattle, fire suppression, and climate change. Landowners and federal and state agencies have utilized treatments to open rangelands for livestock and improve habitat for pronghorn antelope (Antilocapra americana americana), which are grasslands obligate species. Treatments can encourage the growth of understory vegetation species of importance to cattle and pronghorn by eliminating tree canopy.;In the summer of 2008 five study site were monitored on the Campbell Ranch. Monitoring took place to measure vegetation on treated versus untreated pinyon-juniper habitat. Four sites were located on treated land and one site was located in untreated pinyon-juniper woodland. Treatments on the four treated study sites varied in ages from over twenty years to a few months. The vegetation species chosen for monitoring during the study were of significant importance as forage and browse species for cattle and pronghorn. The vegetation species were Blue grama (Bouteloua gracilis), Side oats grama ( Bouteloua curtipendula), Smallflower globemallow (Sphaeralcea parvifolia), Russian thistle (Salsola spp.), Wright's buckwheat (Eregonium wrightii), and Rubber rabbitbrush ( Chrysothamnus nauseousus). The study found vegetation frequencies and species diversity were highest overall on the treated sites. The untreated site had extremely low species diversity and only a moderate frequency of blue grama.