Does kangaroo rat graminivory contribute to the persistence of desertified shrublands?

Title	Does kangaroo rat graminivory contribute to the persistence of desertified shrublands?
Publication Type	Conference Paper
Year of Publication	2002
Authors	Kerley G.IH, Whitford WG
Conference Name	87th Annual Meeting, Ecological Society of America
Date Published	August 4-9, 2002
Conference Location	Tucson, AZ
ARIS Log Number	139791
Abstract	Medium-sized kangaroo rats (Dipodomys merriani and D. Ordi) have been shown to be keystone species in the dynamics of desert bunchgrasses, and the mechanism has been suggested to be through direct graminivory of the grasses. We tested the hypotheses that kangaroo rats preferentially consumed grasses from small tussocks or tussocks that were surrounded by open habitat by observing the extent and effects on growth and inflorescence production of graminivory in grasses from which kangaroo rats were excluded, as well as on grasses varying in tussock size or the extent of surrounding cover. Our data support the above hypotheses with grasses protected from kangaroo rat graminivory showing significantly elevated leaf growth, tiller growth and inflorescence production. Grass tillers subject to kangaroo rat graminivory did not recover and produce inflorescences when protected from kangaroo rats. Furthermore, grass tussocks that were protected by surrounding vegetation or large grass tussocks suffered significantly lower graminivory than tussocks in the open or small tussocks, respectively. We used these observations to develop a conceptual model whereby kangaroo rats may contribute to the persistence of desertified shrublands.