Fenología de un arbusto del sotobosque y ornitocoria en relación a claros en una selva subtropical de montaña del Nororeste argentino

Abstract

In forest ecosystems, avian seed dispersal into treefall gaps is sometimes enhanced by the increased fruit production in the gaps that may atract dispersers. This work was carried on in the subtropical montane forests of NW Argentina with the objectives of assessing 1) if fruit production of the understory shrub Psychotria carthagenensis occurs earlier in treefall gaps than under unaltered canopy, 2) if mist-net bird capture rate is higher in treefall gaps than under unaltered canopy, and 3) if avian- dispersed seed input is greater in treefall-gaps. We sampled five sets of paired plots (gap and closely- located unaltered forest). Fruit maturation occured significantly earlier in treefall gaps. Bird captures did not show a clear patter. However, the second most abundant bird species (Thraupis sayaca) ocurred aboutthree times more frequently in treefall gapsthan under unaltered canopy. Seed dispersal of Psychotria carthagenensis and the canopy tree Myrsine laetevirens was significantly greater in treefall gaps. This pattern could be ecologically meaningful for M. laetevirens given that it is the only tree species with fleshy fruits during winter (dry season), and that its fruiting phenology overlaps with the plants of P. carthagenenis located in gaps. We conclude that disturbances, in addition to producing spatial heterogeneity, promote temporal patterns in the tree community, mediated by understory phenology. Treefall gaps act as atractive patches for dispersers during winter, when the number of fleshy-fruit species is stnall.