Abstract:The effects of fragmentation and overstorey tree diversity on tree regeneration were assessed in tropical rain forests of the Western Ghats, India. Ninety plots were sampled for saplings (1–5 cm diameter at breast height (dbh); 5×5-m plots) and overstorey trees (>9.55 cm dbh; 20×20-m plots) within two fragments (32 ha and 18 ha) and two continuous forests. We tested the hypotheses that fragmentation and expected seed-dispersal declines (1) reduce sapling densities and species richness of all species and old-growth species, and increase recruitment of early-successional species, (2) reduce the prevalence of dispersed recruits and (3) increase influence of local overstorey on sapling densities and richness. Continuous forests and fragments had similar sapling densities and species richness overall, but density and richness of old-growth species declined by 62% and 48%, respectively, in fragments. Fragments had 39% lower densities and 24% lower richness of immigrant saplings (presumed dispersed into sites as conspecific adults were absent nearby), and immigrant densities of old-growth bird-dispersed species declined by 79%. Sapling species richness (overall and old-growth) increased with overstorey species richness in fragments, but was unrelated to overstorey richness in continuous forests. Our results show that while forest fragments retain significant sapling diversity, losses of immigrant recruits and increased overstorey influence strengthen barriers to natural regeneration of old-growth tropical rain forests.

Civets are considered potentially important seed dispersers in tropical forests of Asia, but relatively little is known about spatial patterns of dispersal and post-dispersal fates of civet-dispersed seeds. We explored these aspects of civet seed dispersal for two tree species Vitex glabrata (Lamiaceae), also known as smooth chaste tree and Prunus ceylanica (Rosaceae), in Pakke Tiger Reserve, a tropical forest reserve in northeast India. Pakke has five known species of viverrids: small Indian civet (Viverricula indica), large Indian civet (Viverra zibetha), common palm civet (Paradoxurus hermaphroditus), masked palm civet (Paguma larvata) and the binturong (Arctictis binturong). For both tree species, civets as a group dispersed seeds (100% of scats that we found) within 50 meters from fruiting trees and deposited seeds onto multiple substrates including tree branches, forest floor, and fallen logs. However, the distribution of seeds among substrates differed for the two tree species: while most seeds of V. glabrata (> 90%) were deposited onto canopy branches and fallen logs, the majority of P. ceylanica seeds (> 70%) were deposited on the forest floor. For both tree species, seeds deposited on logs experienced higher seed predation than seeds on the forest floor, especially when local seed densities (number of seeds in 1m 2 area around the scat and in the scat) were high. Further, seed viability of P. ceylanica was significantly lower on logs (~35%) than on the forest floor (~65%). For both tree species, civets neither dispersed seeds far from fruiting trees nor to sites where seeds experienced either low predation or high survival, suggesting that while civets were legitimate dispersers, they were not especially effective.