Influence of microhabitat on the process of seed predation in a degraded area

Abstract

Degraded areas are generally colonized by native pioneer species which are replaced by late successional native species over time; however, many exotic species may take advantage of these disturbances. Pioneer species have great potential to alter future community structure by creating microhabitat heterogeneity and influencing processes of seed predation. We have investigated how patterns of seed predation and removal of Araucaria angustifolia (native species) and Pinus taeda (exotic species) can be altered in distinct microhabitats composed of native pioneer species. In a degraded area we introduced seeds of Pinus and Araucaria in three microhabitats: open area, under Baccharis uncinella crown and under Vernonia discolor crown. For each microhabitat seeds were either caged or not caged (control). Treatments were applied in 10 blocks of replications. A significant interaction between time x habitat x consumer treatments revealed lower rates of Auraucaria seed consumption by vertebrates in open areas compared to the other microhabitats. The fauna played an important role in the consumption of exotic Pine seeds. The behavior of vertebrate seed consumers can be altered by the microhabitat but its influence is more intense on the native species when compared to the exotic species. This work demonstrates that seed predators may control the colonization of the native Araucaria tree and may function as a filter for exotic Pine invasion in degraded areas.

Key words: seed predation, microhabitats, Araucaria, Pinus, restoration, plant invasion.