Diversity of shrubs along gradients of elevation and disturbance in central Veracruz, Mexico

Abstract

Background and Aims: Shrubs are an important floristic element of tropical forests; however, research on plants with this growth form is still scarce. The main objective of this study was to analyze the influence of elevation and disturbance on shrub richness and distribution patterns in the central region of Veracruz, Mexico. Methods: An elevational gradient (20-3500 m a.s.l.) was established along the eastern slopes of the Cofre de Perote, where floristic sampling was conducted at eight study sites within elevational belts of approximately 500 m each. We recorded the abundance of shrubs within 120 plots of 20 × 20 m, distributed in three habitats: conserved, disturbed and secondary forest. The species richness and floristic composition were analyzed, and the resulting data were compared between the different elevational belts and degrees of forest disturbance. Key results: We recorded 118 species and 14 morphospecies of shrubs, representing 8.6% of the shrubs reported for Veracruz. The forest fragments at elevations of 500 and 1000 m are the most species-rich; however, these are the most susceptible to human activities. The anthropogenic disturbance of these forests can increase species richness locally, but at the same time modifies the floristic composition from a conserved habitat to a secondary one. Conclusions: The present study is the first in the Neotropics that considers and analyzes shrubs as an individual group along a complete gradient using a uniform and comparable sampling method. This enabled us to detect which fragments of conserved, disturbed or secondary forest are highly diverse and at the same time susceptible to human disturbance. These sites can serve as strategic buffer zones and refuge of this group of plants, since regardless of their use intensity, they could and should be considered in future conservation plans in this region threatened by environmental degradation.