Effects of urbanization on the diversity of ant assemblages in tropical dry forests, Mexico

Abstract

Urbanization has a direct effect on the landscape and its biodiversity, however urban centers has been ignored in most ecological studies. We study the diversity of ant communities in four remnants of tropical dry forest with different degrees of disturbance which are on the edge of the urban area in Queretaro city, Mexico. Samples were collected two times per month, from December 2004 to December 2005, in four strata: leaf litter, ground, scrub and arboreal. . A total of 25 species and 23 morphospecies were captured, belonging to 28 genera of 6 subfamilies: Dolichoderinae (3 species), Ecitoninae (5), Formicinae (12), Myrmicinae (24), Ponerinae (2) and Pseudomyrmicinae (2). Across the urban-disturbance gradient here studied the local diversity pattern could be explaining by the disturbance heterogeneity model. The most negative effect of urbanization was found for arboreal ants, while leaf litter communities were less susceptible to anthropogenic changes. In general, we found low rates of turnover, even in sites with high values of alpha diversity, evidencing the impoverishment of the ant community surrounding Queretaro city and the susceptibility of the community to extinction. The remnants were functionally very dissimilar and the effects of urbanization depend largely of the diet and life history of individual ant species. Moreover, it was found that the soil proprieties and vegetation structure influenced patterns of ant diversity along the urban-disturbance gradient. Despite the anthropogenic disturbance of the tropical dry forests surrounding the city of Queretaro, these forest remnants serve as a refuge for rare species and prove ecosystem functions. Ant biodiversity is also indicative of the state of ecosystem functions inside these remnants and likely of the biodiversity of other groups. Therefore, the conservation of these sites must be promoted to protect ant biodiversity and other taxonomic groups.