Ant biodiversity in an arid urban landscape

Background/Question/Methods

Urban environments are capable of sustaining considerable diversity of some animal taxa. Ants are an excellent example of this. They are important for city inhabitants due to their capacity to provide ecological services and their potential to become pests.  At this time, the knowledge of the ant assemblages in highly modified urban environments is fragmentary. The goal of this study is to characterize the diversity, abundance and composition of ant assemblages in contrasting urban environments in Tucson, AZ. We expect that our results will have implications for ant conservation in urban environments and the prevention of pest outbreaks. We sampled the ant communities in three contrasting environments around the city: municipal parks, small urban remnants of the native desert and unfragmented natural desert. Sampling was carried out with pitfall traps during the fall of 2010 and the spring of 2011. Although a total 36 sites were sampled for this project, here we are presenting preliminary results from 12 of those sites. 

Results/Conclusions

We collected a total of 11,441 ants in 35 species from the sites analyzed so far. The composition of ant assemblages was significantly different among the three kinds of environments considered. Parks had the highest ant density of any environment, probably as a result of increased water availability due to irrigation. When individual sites were considered, natural desert sites included higher ant diversities than either parks or desert remnants. This pattern was maintained when diversity was compared at the landscape level. Park sites studied were remarkably similar to each other in the composition of their ant assemblages, which partially explains their low gamma diversity. Almost all species encountered were native ants, with the exception of the rover ant, Brachymyrmex patagonicus, which was only found in parks. Although our results are preliminary, they strongly suggest that parks have a low potential for ant conservation and are possibly sources for ant pests. Conversely, desert remnants seem to be able to mantain a significant portion of the native ant diversity of the region without generating pest outbreaks.