Invasive plants in private neighborhoods: Does neighborhood governance make a difference?
Cech, Sarah Jean
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Ecologists have studied the mechanisms, communities, distribution, and characteristics of invasive plants in both natural and urban environments. Evidence suggests that urban/suburban land uses are highly disturbed and therefore have higher rates of invasive species. Anthropogenic and ecologic factors were examined as contributors to the spread of invasive species, but very few studies investigate how and if written policy effects invasive species distribution. Nearly all subdivisions built in the last 20 years have neighborhood covenants. This study asks two questions. 1) Does the level of environmental regulation within subdivisions affect the non-native plant richness? 2) What other factors within the boundaries of the subdivision contribute to the non-native plant richness? Nine private communities in South Carolinas Lowcountry were assigned a governance level (strict, moderate, or not strict) with regard to environmental policies. Plant surveys were conducted in the common land of each subdivision. The land covers for each subdivision were digitized in ArcGIS. Multiple regression analysis was then conducted to determine the best model for predicting the presence of non-native plants in subdivisions. Examination of descriptive statistics revealed that subdivisions with minimal environmental governance had higher percentages of non-native species and non-native richness. Multiple regression analysis run at different scales revealed that governance level does affect non-native richness and the percent of non-native species. Land cover was also factored into the regression models. Predictors were divided into social and environmental variables and models were run with these variables separate and together. The strongest models occurred when all of the variables were included as predictors, showing that anthropogenic and ecological factors cannot be considered separately in studies of plant communities. These results also indicate that human policy decisions can influence species composition. Subdivision planners, therefore, should consider writing regulations about invasive species into the neighborhood covenants.