A test of the Janzen-Connell model with two common tree species in Amazonian forest
Journal of Tropical Ecology
1997
Journal Article
13
5
641-658
Parque Nacional del Manu Cocha Cashu plants trees ecology small spatial scales Janzen-Connell palms Arecaceae Astrocaryum murumuru Fabaceae Dipteryx micrantha seeds seedlings seed dispersal experiments survival mortality seed predation Madre de Dios Bibliography
Field experiments and survival analysis were used to test whether the Janzen-Connell model operated for two common Amazonian tree species in Peru: the midstorey palm, Astrocaryum murumuru, and the canopy-emergent legume, Dipteryx micrantha. Seed and seedling survival patterns of these species partially supported the model, depending on tree species, type of predator, spatial scale and the particular year. At a small scale of a 2.5-ha plot, Astrocaryum seed predation by insects and mammals was density-dependent. At a larger scale of 100 ha, Dipteryx seed survival increased with distance from conspecific adults, but for Astrocaryum seeds there was no distance dependence. At the scale of 200-400 ha Dipteryx seed survival was negatively related to the number of individuals present in groups of conspecific adult trees. In 1992 a higher proportion of Astrocaryum seedlings survived far from, compared with close to, conspecific adult trees, whilst in 1993 more Dipteryx seedlings survived beneath conspecific adult trees than farther away.