Urbanization is rapidly increasing, irrevocably changing ecosystems and inducing numerous impacts on reptiles. We focused on how land cover and vegetation change due to urbanization could affect lizards in riparian forests in arid lands. Using visual encounter surveys in riparian forests along the Salt, San Pedro, and Gila Rivers in central Arizona, we compared lizard community diversity, richness, and species abundance across urban and non-urban habitats. Using land cover and herpetofauna species data from a long-term ecological research center in Phoenix, we related species abundance to environmental variables. Using satellite imagery, we gathered urban habitat data such as the amount of developed land, surface temperature, noise pollution, and human population density. We also gathered vegetation habitat variables such as plant cover type, tree cover percentage, and the Normalized Difference Vegetation Index for each study site. We used this data to determine how lizard community diversity, richness, and species abundances varied across urban and non-urban habitats, and which habitat and environmental variables were good predictors of species to provide management recommendations about conservation.
Results/Conclusions
We found that lizard community diversity and richness were negatively correlated with high human population density, high noise pollution (> 60 decibels), and areas covered by developed land (hotspot analysis, p< 0.05). We also found that non-urban riparian areas had higher tree cover and supported a significantly higher abundance of the tree associated lizard, Urosaurus ornatus, compared to urban habitats (p= 0.02). Urban habitats had less tree cover and contained a significantly higher abundance of a common open-area associated lizard, Uta stansburiana (p= 0.01). This may indicate that urban riparian habitats in Phoenix are not suitable for the same suite of riparian lizards, which can help us identify what is missing in these urban areas, such as vertical foraging and perching habitat. We suggest planting more trees in urban riparian areas in order to support tree-associated lizards, and therefore, help maintain the same species as non-urban habitats. This may also help urban habitats support a higher diversity of species, which would lead to higher ecosystem stability.