Variation of the plant diversity in a successional mosaic in the Andean Central Cordillera (Antioquia, Colombia)

Abstract

Variation of the plant diversity of five remnants of secondary wet forest was studied at different successional stages in the Cordillera Central of the Colombian Andes, at 750-1100 m. Several transects were used (50 m x 2 m) for the analysis, and the total area analyzed was 2000 m². Only individuals with
a dbh ³ 2.54 cm were considered. Structural analysis revealed 837 individuals belonging to 145 species distributed among 60 families. The richest families were Leguminosae (14 species), Melastomataceae (12), Rubiaceae (10), and Arecaceae, Clusiaceae and Lauraceae (7 species each). Species-rich genera were Miconia (7 species) and Inga (6 species). About 74% of the species were represented by less than three individuals, showing a very homogenous distribution. Pielou’s Evenness Index J’ showed values close to 1. Simpson’s Index D’ revealed low dominance, contrary to what is expected for secondary forests. Floristic similarity was estimated based on Czekanowski’s Index, which showed values lower than 16%
between remnants. This demostrates great variation in the floristic composition of the study area. Linear regression analysis showed no relationships between age of the remnants and diversity, species number, evenness, and dominance. This suggests that the most advanced successional stages are not necessarily more diverse than the younger ones. A balance of the number of species is reached early in the successional process in the area investigated. However, the remnants are in a taxonomically unstable condition, as was demonstrated by the strong variation in the floristic composition among remnants. This study demonstrates that there is a balance between local inmigration and extinction.