Nut predation and dispersal of Harland Tanoak Lithocarpus harlandii by scatter-hoarding rodents

Abstract

Plants that use the propagule to co-opt animals as dispersal agents must balance the costs of seed predation with the benefits of dispersal. Successful post-dispersal germination is a key metric that reflects these costs and benefits. By tracking individual nuts with coded tin-tags over 3 years (2000–2003), this study quantified nut predation and dispersal of harland tanoak (Lithocarpus harlandii) by seed-caching rodents in a subtropical evergreen broadleaved forest in the Duiangyan Region of Sichuan Province, Southwest China. We found that tanoak seedlings established from rodent-generated caches in the primary stands over a 12-month post-dispersal period. Our results indicate that seed-caching rodents are effective dispersers of tanoak nuts, but dispersal effectiveness varies among years and stands, probably due to mast seeding of harland tanoak or community-level seed availability according to the predator satiation hypothesis. Some nut traits in tanoak species, e.g. large seed size, hard nut husk, lower tannin and mast seeding, are important characteristics for seed dispersal by scatter-hoarding rodents, compared with oak species with higher tannin content.