Abstract

YEPES-QUINTERO, Adriana P.; JARAMILLO-RESTREPO, Sandra L.; DEL VALLE-ARANGO, Jorge I.  and  ORREGO-SUAZA, Sergio A.. DIVERSITY AND FLORISTIC COMPOSITION OF SUCCESSIONAL ANDEAN FORESTS OF THE PORCE REGION, COLOMBIA. Actu Biol [online]. 2007, vol.29, n.86, pp.107-117. ISSN 0304-3584.

Some studies indicate that tropical secondary succession is to be affected by factors such as disturbances, distance from original forests, surface configuration, and local climate, determining not only the composition of species but also the time trend of the succession itself. This study seeks to understand the dynamics of successional processes in soils devoted to cattle ranching over various decades in the Porce region of Colombia. A set of 25 permanent plots was measured, including 9 plots (20 x 50 m) in primary forests and 16 (20 x 25m) in secondary forests. The age of secondary forests was estimated in previous studies, using radiocarbondating, aerial photographs and a high-resolution satellite image. Both diversity and composition of species in secondary forests were calculated, and the results were compared against those obtained from natural forests located in the same study area. In total, 220 and 197 species were identified in primary and secondary forests, respectively. The floristic composition for both vegetation types was significantly different, indicating a high Beta diversity. Multivariate analyses suggest the existence of a well-defined successional gradient, and a high correlation between composition of species and some environmental variables as well. However, the study area is characterized by a successional process highly degraded, which seems to be the obvious consequence of the previous land use. The importance value index indicates that Anacardium excelsum (Anacardiaceae) and Vismia baccifera (Hypericaceae) tend to be the dominant species in primary and secondary forests, respectively. The importance value index and the presence or absence of species show that the ecological behavior of various species of the successional gradient may be explained by both the relay and original floristic composition. This finding might be the result of ecophysiological strategies of the species and environmental attributes of the ecosystems, which are experiencing slow but natural recovery.

Keywords : diversity; floristic composition; land use; primary forests; secondary forests; successional gradient.

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