Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/20/2012
Publication Date: 8/10/2012
Citation: Longland, W.S., Dimitri, L.A. 2012. Mutualistic interactions between granivorous heteromyid rodents and a preferred food resource, Indian ricegrass (Achnatherum hymenoides) [abstract]. Annual Meeting of the American Society of Mammalogists. p. 182.
Technical Abstract: Granivorous heteromyid rodent species and Indian ricegrass (Achnatherum hymenoides) are both widely distributed throughout North American deserts. The vast majority (~95%) of Indian ricegrass seedling recruitment occurs from seed clusters cached in shallowly-buried scatterhoards by heteromyids, especially Merriam’s kangaroo rat. Here, we discuss how emergence of seedlings in aggregated clusters from scatterhoards affects subsequent seedling survival and establishment. In two western Nevada field studies, we monitored single Indian ricegrass seedlings and clumped seedlings in scatterhoards over the course of a year. Whole caches routinely had higher survival than single seedlings. We followed these observational studies with a field experiment in which Indian ricegrass seedlings were transplanted inside fenced plots either singly or in clumps of 25 or 35 seedlings and survival was compared through their first winter. Individual seedlings within clumps had higher survival than single seedlings, and clumps of 35 seedlings generally had maximum survival. These results suggest a mutualism involving heteromyid rodents and Indian ricegrass. Indian ricegrass seeds provide a highly preferred food resource to heteromyids, and benefits to Indian ricegrass can extend beyond seed dispersal and seedling emergence. Finally, we discuss implications of this work for arid-land restoration.