Seeds and seedlings of two neotropical montane understory shrubs respond differently to anthropogenic edges and treefall gaps

Edges resulting from forest clear-cutting and treefall gaps can affect plan t populations and consequently the distribution of species across landscape s. These two types of disturbance might interact to exacerbate or ameliorat e "edge effects'', a rarely tested possibility. We focused on the effects o f distance from forest edge (0-10, 30-40, 60-70, and 190-200 m) and habitat within forest fragments (treefall gaps and intact forest) on the early sta ges of development of Palicourea gibbosa and Faramea affinis, two common sh rubs of montane forests in southwest Colombia. Seed germination and seedlin g growth did not change with distance from forest edge. Within forest fragm ents, however, seed germination and seedling growth were higher in treefall gaps than in intact forest understory for both species. In contrast, seed predation was influenced by distance from forest edge and in P gibbosa it d epended on habitat. Seed predation was highest in the forest interior (190- 200 m from forest edge) and in P. gibbosa this was true only in treefall ga p habitats. These results suggest that animal mediated processes such as po st-dispersal seed predation are more likely than physiological processes to be affected by anthropogenic edges. Our results provide some evidence that treefall gaps may interact with "edge effects", however, they are inconclu sive as to whether they exacerbate or ameliorate them.