Environmental heterogeneity, recruitment limitation and the mesoscale distribution of palms in a tropical montane rain forest (Maquipucuna, Ecuador)

The study presented here investigated the importance of environmental heterogeneity and clumping for the mesoscale distribution patterns of five palm species in old-growth Andean forest (Maquipucuna, Ecuador). Seedlings, juveniles and adults were recorded in 167 plots located throughout the 3-km X 3-km study area. Mountain (Cerro Sosa or Cerro Sta. Lucia), altitude, aspect, topographic-edaphic conditions and forest structure were also recorded. The following questions were investigated: (1) Are the distributions related to environmental heterogeneity? (2) Are the distribution patterns consistent with severe recruitment limitation? The distribution patterns of four species were related to environmental heterogeneity, especially to that created by the mountainous landscape itself, and at least four of the five species also exhibited strong clumping that was clearly linked to spatially restricted recruitment and could not be explained by the environmental parameters. Thus, both niche specialization and recruitment limitation probably play important roles in Andean palm community ecology. Consistent differences among the two mountains in forest structure and the frequency of certain palm stages most likely reflected extractivism.