Effect of slope exposure on the structure and diversity of a submontane scrub in Northeast Mexico

Abstract

Slope exposure is one of the environmental factors that influences vegetation characteristics. Although there are studies on this aspect in various types of vegetation, up to now submontane shrublands have not been extensively studied. In this work, the effect of slope exposure on the structure and composition of plant species in a state park in northeastern Mexico where the dominant vegetation is submontane scrub was evaluated. Ten 10 x 10 m exposure sites were sampled: northeast, southwest and northwest. Total height (h), basal diameter (d_0.10) and crown diameter (k) were measured for each individual. Our hypotheses were: 1) the northwestern exposure community will have greater basal area, canopy cover, volume, absolute abundance, and specific richness due to higher humidity, 2) each slope will present dissimilarity in species composition. As results, nine families, 17 genera and 17 species of vascular plants were recorded. Fabaceae was the best represented family with six species. The species with the highest importance value index were the endemic shrub Neopringlea integrifolia in the northeast exposure (21.52 %) and the exotic tree Leucaena leucocephala in the southwest (16.17 %) and northwest (27.16 %) exposures. It is concluded that the plant community of the northwest exposure has a greater basal area, crown cover, volume, absolute abundance and specific richness. However, there was no real difference in the species composition of the three exposures.