Impactos da invasão de Prosopis juliflora (sw.) DC. (Fabaceae) sobre o estrato arbustivo-arbóreo em áreas de Caatinga no Estado da Paraíba, Brasil

Abstract

It is estimated that invader populations of algaroba Prosopis juliflora (Sw.) DC. (Fabaceae) in the northeastern semi-arid, Brazil, cover more than one million ha. This study aimed to study the impacts of P. juliflora invasion on phytodiversity and on the structure of the shrub-tree component in caatinga fragments in Paraiba state. Four environments were sampled by plots in which all shrubtree individuals were surveyed and measured, estimating structural parameters of the communities. Diversity was estimated by the Shannon-Wiener index (H'), and the index of environmental impacts of exotic species (IIAE) was also calculated. A total of 19 families, 35 genera and 39 species were surveyed. Invader species accounted for more than 70% of the entire structure of the surveyed environments. The low diversity and the high environmental impact indexes obtained, as well as the structure of populations on the invaded communities, reveal that native communities are seriously jeopardized by P. juliflora. Interventions aiming at effective control of P. juliflora are recommended to protect the genetic heritage of native species.