부산대학교 도서관

Background: In central Amazonia, previous low intensity land use engenders succession dominated byCecropiaspp. which proceeds at high rates; however, at higher intensity of use succession is arrested and dominated byVismiaspp. over the long-term. Factors driving these two successional pathways are unknown. Aims: We aimed to elucidate seedling growth under the two alternative successional pathways. Methods: We experimentally determined the effects of successional age and photosynthetically active radiation (PAR) on relative height growth (RHG) of nine species of shade-tolerant tree seedlings in secondary forests dominated byCecropiaandVismia, varying in age from 1–20 years. Results: InCecropia-dominated successions, seedling RHG decreased with increasing successional age and with associated decreasing PAR. InVismia-dominated successions, RHG was independent of successional age and PAR, and PAR did not change with successional age, being always higher than inCecropiastands. The RHG of seedlings was lower inVismia- than inCecropia-dominated stands for similar PAR levels. Conclusions: Successional age and light availability affect seedlings growth differently in the two successional pathways. Unlike inCecropia-dominated successions, inVismia-dominated secondary forests seedling growth is limited by factors other than light. In a scenario of increasing land use intensity, constraints to seedling development in secondary forests can reduce species diversity in human-altered landscapes. [ABSTRACT FROM PUBLISHER]