干旱区生态环境知识资源中心

Graminivory by kangaroo rats (Dipotomys spp.) was investigated as a potential mechanism fur the keystone role of these rodents in the dynamics of desert grasslands. Experiments confirmed that Ord’s kangaroo rats (Dipodomys ordii) cut and consumed a large proportion of the tillers of three Chihuahuan Desert tussock-forming grass species. Field observations indicated that the characteristically cut grass tillers were absent from all-rodent and medium-sized kangaroo rat exclosures, but were frequent in large-sized kangaroo rat and rabbit exclosures. indicating that the medium-sized kangaroo rats (D. ordii, D. merriami) were responsible for grass cutting. Tiller waste as: a, percentage of peak standing crop ranged from 7% in grassland habitats to 0.7% in Flourensia cernua shrubland. OF the 13 species of perennial, tussock-forming grasses measured, only one, Muhlenbergia porteri, had no tillers cut by kangaroo rats. This study demonstrates that the keystone role of kangaroo rats in Chihuahuan Desert grassland ecosystems is probably the result of their graminivory.