The Impacts of Sprawl on Biodiversity: the Ant Fauna of the Lower Florida Keys

Abstract

ABSTRACT. Sprawling development can affect species composition by increasing the rate of invasion by non-native species, and decreasing the persistence of native species. This paper briefly reviews the scientific literature on the impacts of sprawl on biological diversity, with specific emphasis on the influence of sprawl on non-native species richness. We then explore the relationship between sprawl and biodiversity using a data set of ant species collected from 46 habitat patches located in the increasingly suburbanized Florida Keys, USA. We quantified sprawl as the proximity of roads and amount of development surrounding a habitat patch. Using bait transects, we identified 24 native and 18 non-native species of ants. Neither the overall number of native species nor the number of rare native species were significantly affected by the amount of development or proximity to roads, however, the number of non-native species was significantly correlated with the amount of development. Surprisingly, the number of native species and rare native species was significantly positively correlated with the number of non-native species. Areas that supported many species of native ants also supported a diverse non-native ant fauna, and the species distribution was highly nested. Currently, the native ant fauna of the Florida Keys does not appear to be dramatically influenced by sprawl, however, if development increases, the number of non-native ants may increase, and many of these species have been documented as decreasing native ant diversity. If development plateaus, there is evidence that the native ant fauna could persist and could decrease non-native species richness through competition or predation.

Exurban development influences woodland bird composition

“…Two of the most comprehensive field studies completed to date demonstrate significant effects of subdividing private ranches on bird, carnivore, and plant communities in Colorado (Odell and Knight, 2001;Maestas et al, 2001). On the other hand, differences in the presence of native ant species were not detected in southern Florida, despite marked increases in exotic ants found at exurban sites (Forys and Allen, 2005). The same was true for ants and small mammals in the Sierra Nevada, California (Manley et al, 2006), although the lack of detectable effect could represent an extinction debt that will lead to the loss of native species over time (Tilman et al, 2002).…”

Urban areas may serve as habitat and corridors for dry-adapted, heat tolerant species; an example from ants

“…Most studies on ants have focused on fragments of natural habitats in urban environments and the differences in species richness across urban to rural gradients, with often inconsistent patterns between cities (McKinney 2008;McIntyre 2009). For example, a number of studies of ants have shown decreases in species richness in urban environments (Pisarski and Czechowski 1978;Suarez et al 1998;Malozemova and Malozemov 1999;Yamaguchi 2004;Lessard and Buddle 2005;Pacheco and Vasconcelos 2007;Thompson and McLachlan 2007;Clarke et al 2008) though others have shown little to no difference (Carpintero et al 2003;Gibb and Hochuli 2003;Forys and Allen 2005;Vepsäläinen et al 2008).…”

Effects of Urban Sprawl on Riparian Vegetation: Is Compact or Dispersed Urbanization Better for Biodiversity?

“…Blair () identified different effects of urban sprawl on birds at multiple levels of organization, detecting that species richness and diversity peaks at intermediate levels of urbanization. Forys and Allen (Forys & Allen, ) found that neither native nor rare ant species were significantly affected by urban sprawl, whereas exotic species richness was positively correlated with the amount of development. Concepción et al () found important impacts of urban sprawl on species richness of plants and birds, which varied considerably depending on the species groups, urban sprawl components and spatial scales considered.…”