PARENT SESSION
Poster Session #14: Dispersal.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Soil particle size affects caching and pilfering behavior of Peromyscus : Implications for pinon pine dispersal.

Pearson, Kristen^*,1, Theimer, Tad, ¹ Northern Arizona University, Flagstaff, AZ

ABSTRACT- The effectiveness of a seed disperser depends upon the quality of microsites choosen for seed storage. Soil particle size is one potentially important characteristic for dispersed seeds: influencing soil moisture, nutrient dynamics and thus could ultimately affect germination and seedling survival. We examined how soil particle size influenced caching and pilfering behaviors of mice (Peromyscus spp.), potentially important seed dispersers of pinon pine (Pinus edulis) growing on cinder soils of northern Arizona. Rodents were allowed to cache and pilfer pinon seeds from large or small particle size plots in experimental field enclosures. Effects of particle size on pinon germination were determined by planting seeds in soil cores of either small or large cinder particles. We found that: 1) rodents cached seeds in small particle soil in 91% of the trials, 2) there was no significant difference in pilfering rates between the two particle sizes, 3) germination rates were 50% higher in the small particle size soil cores. These results suggest there is a net movement of seeds into small particle cinders and therefore, potentially more seeds left undetected due to equal pilfering rates between the two particle sizes. This may result in a greater number of seeds available for germination in small particle cinders where germination potential is higher. These findings indicate rodents may act as important qualitative dispersers, benefiting pinon pine through seed dispersal to favorable microsites for germination.

KEY WORDS: Soil particle size, Seed dispersal, Peromyscus, pinon pine (Pinus edulis)