EFFECT OF THE RECURRENCE OF FOREST FIRES ON TREE DIVERSITY

Abstract

Forest fires are a natural phenomenon that has been present in most terrestrial ecosystems. The La Primavera forest has been frequently affected by fire through the last few decades, and knowledge of the benefits or damages that it generates in the adaptation of species is still incipient. This paper evaluates the spatio-temporal recurrence of forest fires and their effect on tree diversity in the La Primavera forest. Layers of the fires of the 1998–2012 period were superimposed according to their recurrence on the same surface using geoprocessing techniques, and three Fire Recurrence Classes were defined: High, with three fires; Moderate, with two, and Low, with one. Permanent sampling sites (1 000 m2) were randomly established. Sorensen’s and Jaccard’s Similarity Indexes were applied to measure the beta tree diversity, and Shannon’s index, to measure the alpha tree diversity. Six polygons with an incidence of three fires representing a surface area of 833 has were identified. The intersection of fires that occurred during the 1998-2005-2012 and 2000-2002-2005 periods covered the largest surface. The dominant species was Quercus resinosa, followed by Pinus oocarpa. Sorensen’s index indicated that all the categories are similar by over 50 %; while the value using Jaccard’s similarity index was 40 %. The recurrence of forest fires of a large magnitude in the study occurred within very short periods (seven years).