@article {50107,
	title = {Can kangaroo rat graminivory contribute to the persistence of desertified shrublands?},
	journal = {Journal of Arid Environments},
	volume = {73},
	year = {2009},
	pages = {651-657},
	abstract = {<p>Medium-sized kangaroo rats (Dipodomys spp. Gray) function as keystone species in the dynamics of desert bunchgrasses. We tested the hypothesis that kangaroo rat graminivory leads to reduced grass growth and inflorescence production, and that kangaroo rat grass consumption reflects their preferences for open microhabitats. We excluded kangaroo rats from grasses, and measured tiller loss, leaf and tiller growth and inflorescence production. We recorded the extent of tiller loss in grasses varying in tussock size or the extent of surrounding cover. Consumption of tillers by kangaroo rats was extensive, peaking in late summer. Grasses protected from kangaroo rat graminivory showed elevated leaf and tiller growth and inflorescence production. Grass tussocks protected by surrounding vegetation or large grass tussocks suffered lower graminivory than tussocks in the open or small tussocks. Our data demonstrate that the mechanism of the keystone role of kangaroo rats is through direct graminivory. We hypothesize that kangaroo rat graminivory may contribute to the persistence of desertified shrublands by limiting grass recruitment and abundance. Medium-sized kangaroo rats prefer open microhabitats and increase in abundance as such microhabitats increase, suggesting a positive feedback, with kangaroo rats increasing in abundance in overgrazed, desertified landscapes, and then contributing to their persistence through graminivory. {\textcopyright} 2009 Elsevier Ltd. All rights reserved</p>
},
	keywords = {desert bunch grasses, desertification, Dipodomys merriami, Dipodomys ordii, Eragrostis lehmanniana, graminivory, kangaroo rat, keystone species, patch use, positive feedback, small mammals, Sporobolus flexuosus},
	doi = {10.1016/j.jaridenv.2009.01.001},
	url = {files/bibliography/JRN00524.pdf},
	author = {G. I. H. Kerley and Walter G. Whitford}
}
@article {51088,
	title = {Impact of grazing and desertification in the Chihuahuan Desert: Plant communities, granivores and granivory},
	journal = {American Midland Naturalist},
	volume = {144},
	number = {1},
	year = {2000},
	month = {July 1, 2000},
	pages = {78-91},
	abstract = {<p>Livestock effects on plant communities through overgrazing (desertification) should affect the structure and functioning of semiarid rangeland communities. We measured plant, granivorous ant and rodent communities and rates of seed removal by rodents and ants in grazed (by livestock) and ungrazed desert grasslands, as well as mesquite and creosotebush shrublands to test hypotheses on the effects of grazing and desertification on ecosystem structure and functioning. In desert grasslands, grazing reduced the cover of perennial grasses, particularly the dominant Bouteloua eriopoda, but the cover of forbs and shrubs did not differ between treatments. One species of perennial grass, Dasyochloa pulchellum, increased in grazed grasslands compared with grassland exclosures. Detrended correspondence analysis showed that grazing caused desert grasslands to shift in community structure towards the shrublands. There were more seed harvesting ant and rodent species in the creosotebush shrublands than in the grasslands and mesquite shrublands. Grazing had no effect on the diversity of ants or rodents within grasslands, and detrended correspondence analysis revealed no clear trends in granivorous ant community structure in the grazed and ungrazed grasslands or the mesquite and creosotebush shrublands. Ants removed more seeds than did rodents in the grassland sites, but rodents removed more seeds than did ants in the creosotebush sites; seed removal rates by rodents and ants were the same in the mesquite sites. Our data support the hypothesis that livestock grazing leads to a shift from grassland to shrubland in the Chihuahuan Desert with associated changes in the structure and functioning of faunal communities. Because grasslands support few species and low densities of rodents, seed harvesting ants are the most important granivores in these desert grasslands. On a larger scale, we therefore hypothesize that the observed dominance of rodents as seed harvesters in the Chihuahuan Desert is a function of the desertification of desert grasslands to shrublands by livestock and that associated feedback effects may complicate the regeneration of degraded communities.</p>
},
	keywords = {Chihuahuan Desert, desertification, granivores, granivory, grazing, livestock, overgrazing},
	doi = {10.1674/0003-0031(2000)144[0078:IOGADI]2.0.CO;2},
	url = {/files/bibliography/00-010.pdf},
	author = {G. I. H. Kerley and Walter G. Whitford}
}
