A test of the Janzen-Connell model with two common tree species in Amazonian forest

Abstract

ABSTRACTField 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,Astrocaryumseed predation by insects and mammals was density-dependent. At a larger scale of 100 ha,Dipteryxseed survival increased with distance from conspecific adults, but forAstrocaryumseeds there was no distance dependence. At the scale of 200–400 haDipteryxseed survival was negatively related to the number of individuals present in groups of conspecific adult trees. In 1992 a higher proportion ofAstrocaryumseedlings survived far from, compared with close to, conspecific adult trees, whilst in 1993 moreDipteryxseedlings survived beneath conspecific adult trees than farther away.