Usando patrones de biodiversidad para la evaluación y diseño de áreas protegidas: Las serpientes de la provincia de Santa Fe (Argentina) como ejemplo

Abstract

Snakes are usually persecuted by people and few are considered in biodiversity conservation strategies, being protected areas essential for their preservation. We analysed species richness and biogeographical patterns of the snakes of Santa Fe province, Argentina, to prioritise areas for their conservation and to assess if the existent reserves coincide with these areas. Species richness and distributional patterns were established from 2,532 specimens, obtained on field samplings and revision of collections, supplemented with bibliographical records and a regional database of 8,000 specimens. Areas of endemism were determined and compared with phytogeographical divisions. Santa Fe was divided in 16 cells of one degree of latitude and longitude, to compare species richness, similarity and complementarity. We applied a method to prioritise cells for conservation according to species richness and a conservative value of each taxa. Species richness in Santa Fe greatly increased with decreasing latitude and longitude in relation to an increasing gradient of temperature and rainfall. In consequence, the north-eastern cell presents the highest richness (containing 84 % of Santa Fe species and the south-western cell the lowest diversity (20 %). All cells crossed by the Paraná river have a higher richness than the western contiguous cells, probably, due to the corridor effect of this river for tropical and subtropical species. Five areas of endemism were defined, four of them coincide with one or two phytogeographical divisions and they are important in conservation analysis because of the presence of exclusive species. Similarity analysis among cells showed three major groups: the north-west, the north-east-centre and the south. Combined analysis of conservation priority values, areas of endemism, similarity and complementarity among cells showed that populations of all Santa Fe snakes would be conserved by protecting three cells appropriately, located in the north-east corner (Chaco Humid-Paraná valley), the north-west corner (Dry Chaco) and the south-west corner (Pampeana). The first two do not have protected areas and the third cell has a small reserve, an island in the Paraná river, that does not contain Pampean ecosystems. The Dry Chaco region does not have any reserve, showing the major protected areas deficiency. Protected areas surface is insufficient and not adequately distributed in relation to biodiversity patterns due to lack of scientific approaches for their selection. This problem, in addition to serious implementation deficiencies, makes the Santa Fe reserve system ineffective to protect snakes, and possibly, all the provincial biodiversity.