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University of Arizona (1970)

Effects of longtime livestock exclusion versus grazing on the desert grassland of Arizona

Caraher, David Luther

Titre : Effects of longtime livestock exclusion versus grazing on the desert grassland of Arizona

Auteur : Caraher, David Luther

Université de soutenance : University of Arizona

Grade : Master of Science (MS) 1970

Résumé
During 1965, plant cover and forage production measurements were made to study the effects of three grazing treatm ents — open to grazing and protection for 30 and 50 years — on three Desert G rassland sites in southern Arizona. Plant cover did not vary significantly among grazing treatm ents. Cover of mesquite (Prosopis juliflora (Swartz ) DC.) re flected distribution before treatments rather than a result of treatm ents. This prior establishm ent and the overwhelming dominance of mesquite probably prevented other species from reacting significantly to treatm ents. Total grass and the most dominant native grass, Arizona Cottontop (Trichachne californica (Benth.) C hase), varied considerably by sites but the trend was for their cover to vary inversely with mesquite cover, particularly where mesquite cover was less than five percent. The cover of Lehmann lovegrass ( Eraqrostis lehmanniana N ees) was more depend en t on the distribution of native plants than on grazing treatm ents. Forage production did not indicate differences due to grazing treat ment, possibly because sites lacked uniformity or were too few. Short- grasses were sparse and midgrass production trends were confounded with.reactions to mesquite cover and to cover variations of other grasses. Forage production of Lehmann lovegrass correlated with its cover distribution and varied inversely with cover of native species rather than with, treatment.

Mots clés : Grazing — Arizona. ; Rangelands — Arizona.

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Page publiée le 15 juillet 2018