Seed removal patterns by vertebrates in different successional stages of Araucaria forest advancing over southern Brazilian grasslands

Seed dispersal is a limiting factor in the maintenance and distribution of plant communities, especially in rainforest ecosystems where a major proportion of plant species are dispersed by animals. Knowledge of seed removal by terrestrial mammals (particularly small mammals) in Araucaria forest patches scattered in Campos grassland is relatively sparse. In this study, we assessed: (1) whether the removal rate of Araucaria angustifolia seeds differs in different successional stages of Araucaria forest advancing over grassland, and (2) the importance of small mammals and others vertebrates for seed removal rates in each environment type. We used seed removal experiments and camera trapping to answer these questions. Our results showed that seed removal was higher in more-forested sites than in open ones and in control treatment in 2006, we found an interaction between successional stage and treatment in 2007 and, in 2008, only treatments differed significantly. Our photographic records were mostly of small cricetid rodents. Seed-removal increment as a function of forested area suggests increased use of these sites by terrestrial mammals as patches develop in grassland. The use of large patches by mammals may increase the probability of mammal-dispersed plants colonizing patches as they attain a given structural development, which might determine to some degree the future patch nucleation dynamics.