Geographical variation in the fertility, phenology, and composition of the understory of Neotropical forests
Biotropica
1987
Journal Article
19
3
216-227
Parque Nacional del Manu Reserva Nacional Tambopata large spatial scales ecology vegetation floristic composition plant-animal interactions shrubs phenology soils climate seasonality Madre de Dios Bibliography
The tropical forest understory has a different set of species than has the canopy, many species of insects, birds and mammals are restricted to the understory and the vegetation of this stratum is major food source of this community. This study emphasizes in the geographical variation of the understory shrub communities two different approaches: the floristic composition of plant communities and their role as an animal food source. Different levels of flowering and fruiting in 55 samples of neotropical forest understory were compared (13 locations in six countries). In Peru, five localities were evaluated: Cocha Cashu, Mishana, Yanamono, Negro Urco and Tambopata. Transect census of fertile plants were made, and it was found that changes in species richness and density of fertile understory vegetation are correlated with rainfall and soil fertility. Areas with weak or absent dry seasons and intermediate to rich soils, average 64 plant species and 174 individuals per sample, while areas with poor soils and a strong dry season average five species and eight individuals. Areas with either strong dry seasons and good soils or weak dry seasons an very poor soils have intermediate values. Taxonomic composition of the understory also changes with rainfall and soil fertility. In highly disturbed forests, there are changes in understory structure, with sequential loss of terrestrial herbs, epiphytes, understory shrubs and vines. It is suggested that the level of understory fertility may provide a simple indicator of overall ecosystem productivity.