Rareza y Diversidad de Hormigas en Fragmentos de Bosque Seco Colombianos y sus Matrices1

Dry forests in middle Cauca River valley (southwest Colombia) almost have been eliminated from the region and the last remnants are seriously threatened. This study shows the biological value of seven forest fragments, comparing their ant diversity with that of their surrounding matrices. Two intensive ant surveys were made in each forest fragment and its matrix between August 1994 and February 1995. Sampling effort was the same in each of the seven sites. We found that: (1) forest fragments are richer and more diverse than their respective matrices; (2) forests preserve a larger number of rare ant species than the matrices; and (3) the richer the forest, the larger the number of exclusive ant species it preserves. Therefore, these forests must be preserved to maintain regional biodiversity.