Submitted to: Ecological Society of America Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/26/2009
Publication Date: N/A
Technical Abstract: In addition to consuming seeds, many small mammals also cache seeds in shallowly buried scatterhoards, and seeds of many plant species germinate and establish aggregated clusters of seedlings from these caches. Scatterhoards made by desert heteromyid rodents provide the primary source of seedling recruitment for Indian ricegrass (Achnatherum hymenoides), but effects of the resulting clumping of seedlings on subsequent survival have not been quantified in the field. I compared survival of clumped versus single Indian ricegrass seedlings over their first year at two western Nevada study sites to test the hypothesis that clumping has no effect on the seedling survival. At Site 1, I counted single seedlings and seedlings within clumps (i.e., scatterhoards) on 4 plots weekly over their first year. At Site 2, I followed and compared the survival status of 75 clumps and 75 paired single Indian ricegrass seedlings over their first year. Individual seedlings within clumps at both sites had significantly higher survival rates than seedlings growing singly. Individual seedlings within clumps of 41-60 seedlings had significantly greater survival (56%) than those in smaller or larger clusters (< 45%) at Site 1, suggesting that clumping benefits fitness. Benefits accruing to the plant due to seed-caching desert rodents extend past the seedling establishment phase and into long-term survival.