Los hongos poliporoides de la huasteca potosina, San Luis Potosí, México

Abstract

Ecological research on Mexican grasses has focused mainly on some native species of grassland communities and some cultivated pastures, mostly tropical. In this study some ecological aspects of grasses are analyzed and a comparison of the group with the rest of the herbaceous component that occurs within the mesquite woodland in the north central portion of Nuevo Leon state. In order to achieve the best representation, the study was conducted at the intersection between the three state physiographic provinces: North Great Plain, Northern Gulf Coastal Plain and Sierra Madre Oriental, where 20 sample sites in 14 municipalities were established. Agrostological richness and ecological importance of grasses were analyzed and the Values of Importance for species found calculated. Additionally, invasive species were recognized in mesquite communities; the diversity among sites by applying different rates and percentages of species similarity between communities of mesquite is analyzed. 25 grass species were identified, in general less than five species per site. Setaria texana and Bouteloua trifida had the highest importance values. Average density of grasses in studied sites was 43 006 plants by hectare. Overall diversity, evenness and similarity between sites regarding grass was low to moderate because 65% of the sites had less than five species, affecting different disturbance conditions associated with the sites. Setaria texana is proposed as a key species in the grasslands of north-eastern Mexico