PARENT SESSION
Friday, August 11, 8:00-11:30 am
COS 110 - Tropical ecology
Sultana, Mezzanine Level, Cook Convention Center
Presiders: G Selaya

Changes in vegetation structure and relative abundance of tree functional groups along a chronosequence of abandoned pastures in a Mexican cloud forest landscape.

Muņiz-Castro, Miguel Angel¹, Williams-Linera, Guadalupe^*,1, ¹ Instituto de Ecologia, A.C., Xalapa, Mexico

ABSTRACT- In a montane cloud forest region in Veracruz, Mexico, we studied 15 abandoned pastures (0.25-80 years) representing a successional chronosequence. Basal area, density, and height of woody vegetation were related to age in a hierarchical set of six nonlinear models. Tree species richness organized by shade tolerance and dispersal syndrome was also fitted to such models to explain successional patterns by functional groups. The effect of distance from a forest border was also investigated. Basal area reached a value similar to mature forest in 50 years; density peaked at 25 years and reached forest values in 80 years. Moving in the chronosequence, the proportion of shade intolerant tree species changed from 0.68 to 0, intermediate species from 0.24 to 0.29, and tolerant trees from 0.08 to 0.71. Anemochorous species went from 0.52 to 0.17, endozoochorous remained steady at 0.37, and barochorous-synzoochorous from 0.11 to 0.46 along the same gradient. Total species richness, anemochorous and endozoochorous groups were similar close (0-10 m) and away from (40-50 m) mature forest border. However, basal area, height, abundance, and richness of barochorous-synzoochorous species were all higher close to the border. Within 80 years, secondary succession results in recovery of the forest structure but not yet in composition due to limited dispersal capacities of large seeded species.

Key words: tropical montane cloud forest, secondary succession, tree species