Efecto del fuego sobre el reclutamiento de especies leñosas en un bosque seco de la cuenca alta del Río Magdalena.

Abstract

Fire is a frequent and crucial disturbance in some dry ecosystems such as savannas and tropical dry forests (TDF) in Central and Latin America. However, little is known about the capacity of inter-Andean dry forests to recover after a fire. In this sense, we compare the composition and structure of sexual regeneration between burned and unburned sites and evaluate the rates of mortality, recruitment, and growth of woody tree species after a fire in a tropical dry forest of the upper basin of the Magdalena River in Colombia. We install 75 plots of 2x2m where we register and identify all woody individuals in burned, unburned and forest gaps sites. Every three months we recorded and measure the individuals found in 25 plots of burned sites. Results showed that species richness was lower in burned sites, but the number of individuals was significantly higher than in unburned areas. The mortality rate of the post-fire regenerated community was 0,91%, while the recruitment rate was greater (1.93%), which suggests a good post-fire establishment. In the burned sites, recruited species exhibited similar growth rates. Based on the natural regeneration index (TNR) and abundance, species were classified as sexual regeneration fire tolerant-species (e.g. Astronium graveolens, Eugenia procera and Swartzia trianae); species with sexual regeneration fire-stimulated (e.g. Casearia corymbosa, Cordia alliodora and Machaerium capote) and species with sexual regeneration fire-sensitive (e.g. Posoqueria sp., Guarea guidonia, and Piptadenia sp.). Our results suggest that some inter-Andean TDF tree species can survive and regenerate after fire, and therefore they should be considered in restoration programs, in light of more intense and frequent forest fires due to climate change and anthropic intervention.