Utilización de coleópteros como indicadores ecológicos en gradientes urbanos de Gijón y León (NO Península ibérica). (Coleoptera: Carabidae, Cholevidae, Histeridae, Silphidae y Staphylinidae)

Abstract

Both, the use of beetles as ecological indicators and their study in urban-rural gradients, is supported by a big amount of studies and previous research. In the present study the usefulness as ecological indicators of certain families of beetles in urban gradient is evaluated. Two urban-rural gradients were sampled in the cities of Gijon and Leon (NW Iberian Peninsula) in order to use five beetles families (Carabidae, Cholevidae, Histeridae, Silphidae and Staphylinidae) as ecological indicators of urban pressure. Furthermore, the intermediate disturbance hypothesis, the increased disturbance hypothesis, the habitat specialists hypothesis and the opportunistic species hypothesis, were tested. Pitfall traps were used to sample in a gradient comprising an isolated city park, a urban park near a river acting as an ecological corridor, a city park on the edge of the city, a suburban industrial area and a rural area. 18 sampling campaigns were carried out in two years. Data were analyzed using different methods. Richness and alpha and beta diversity indices, general linear models, correlation analysis and the use of the IndVal index were carried out to study the abundance, diversity, indicator species and ordination of the sampled areas. Similar patterns in the composition of beetles communities, in diversity gradients and in the ordination of different sampling areas were observed in both cities. The results do not support the intermediate disturbance hypothesis, as higher values of diversity not found in the areas of intermediate sampling within the gradient. The increase in species richness and diversity as the degree of urbanization is reduced, supporting the hypothesis of increased disturbance. The analyzed data about the habitat preferences of ground and rove beetles and the specialized trophic levels, indicates that the habitat specialists hypothesis and the opportunistic species hypothesis are also support. We conclude that the abundance, diversity, beetles comunities structure and the presence and dominance of certain species are suitable indicators of environmental pressure in urban environments.