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Efecto del Pastoreo de Vertebrados en la Estructura Comunitaria de Plantas e Insectos
Author(s) -
Rambo Jennie L.,
Faeth Stanley H.
Publication year - 1999
Publication title -
conservation biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.2
H-Index - 222
eISSN - 1523-1739
pISSN - 0888-8892
DOI - 10.1046/j.1523-1739.1999.98504.x
Subject(s) - species richness , exclosure , grazing , forb , ecology , biology , grassland , plant community , abundance (ecology) , species evenness , conservation grazing , relative species abundance
We compared species diversity of plants and insects among grazed and ungrazed areas of Ponderosa pine–grassland communities in Arizona. Plant species richness was higher in two of three grassland communities that were grazed by native elk and deer and domestic cattle than in ungrazed areas inside a series of three large (approximately 40‐ha) grazing exclosures. Similarly, plant species richness was higher in grazed areas relative to ungrazed areas at one of two series of smaller (approximately 25‐m 2 ) and short‐term exclosure sites. Evenness of plant distribution, however, was greater inside ungrazed long‐term exclosures but was reduced inside ungrazed short‐term exclosures relative to grazed areas. Relative abundances of forbs, grasses, trees, and shrubs, and native and introduced plants did not differ between the long‐ and short‐term grazing exclosures and their grazed counterparts. Relative abundances of some plant species changed when grazers were excluded, however. In contrast, insect species richness was not different between grazed and ungrazed habitats, although insect abundance increased 4‐ to 10‐fold in ungrazed vegetation. Our results suggest that vertebrate grazing may increase plant richness, even in nutrient‐poor, semi‐arid grasslands, but may decrease insect abundances.