Disperal of ponderosa pine (Pinus ponderosa) seeds by shadow chipmunks (Tamias senex) in a managed forest

I examined dispersal of ponderosa pine (Pinus ponderosa) seeds by the shadow chipmunk (Tamias senex) on thinned and unthinned forest units in the Goosenest Adaptive Management Area (Goosenest Adaptive Management Area) from 2001-2002. I placed 1000 radiolabelled ponderosa pine seeds on three thinned and three unthinned units and tracked the movement of the seeds using a Geiger counter. Tamias senex was the only small mammal observed gathering ponderosa pine seeds at videotaped feeding stations. Seeds were removed from their original locations in less than 24 hours on all but one unit. Between 0.1 and 5.1 % of seeds were found in dispersed caches (1-51 seeds), approximately 1-3 cm under the soil surface 1-7 days after the seeds were deployed. At each cache, I measured the number of seeds (cache size), cache substrate (needle litter or soil), distance moved, and the distance to the nearest trees using the point-centered quarter method. Chipmunks transported seeds farther on thinned than unthinned units (P = 0.027) but cache size (seeds per cache) did not differ significantly between thinned (13.79 ± 1.25) and unthinned (12.84 ± 1.21) units. On unthinned forest units, chipmunks placed caches in areas farther from trees than expected by chance (P = 0.048). Regardless of unit treatment, chipmunks placed caches in soil substrate more often than expected based on its availability (c2 = 173.76, P 0.0001). Chipmunk abundance on each unit was positively correlated with the number of caches found and negatively correlated with the number of seeds per cache (r2 = 0.48, r2 = 0.86, respectively). Average (± SE) number of seeds removed was greater on thinned units (11.4 ± 2.9%/day) than on unthinned units (8.6 ± 2.1%/day). The cone crop in 2002 was very light for ponderosa pines and nonexistent for white fir (Abies concolor). Tamias senex tended to place caches in locations that favored recruitment and establishment of ponderosa pine seedlings (i.e. in mineral soil and in forest openings) and therefore may contribute to the natural regeneration of ponderosa pine forest.