EFFECT OF LIVESTOCK IN THE COMPOSITION AND DIVERSITY OF TREES AND SHRUBS IN THE TAMAULIPAN THORNSCRUB

Abstract

Grazing is carried out in 26% of the land cover, while forage production in 33% of crop lands. In Mexico, livestock is the most common productive activity in the rural scope: it gathers 10 million hectares, that is, 56% of the national territory. The scrub is the most abundant ecosystem and, historically, from which are obtained the greatest number of products in the arid and semiarid zones of the country. This research assessed the impact of livestock in the composition and diversity in different areas of the Tamaulipan Scorncrub. Three were selected: Referencia, Regeneración and Ganadería and four sampling plots of1 600 m2 each were established. Structural variables of abundance, dominance, frequency and the Importance Value Index were determined, in addition to the indexes of species richness, alfa and beta diversity. Twenty-two species were recorded, distributed into 20 genus and 14 families. The ecological weight was represented in the Referencia area by Diospyros texana, in Regeneración by Acacia farnesiana and in Ganadería, by Prosopis laevigata. The study reveals that livestock lowers significantly the abundance, dominance and alfa diversity of the tree and scrub communities and that those resulting, show low similitude among species.