Invasive species in Iowa's woodlands: using volunteers and remote sensing as tools for research

Evans, Christopher
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Natural Resource Ecology and Management

This thesis consists of two papers that focus on woodland invasive species in Iowa. The first paper presents a new method for using volunteers to collect data concerning the distribution and abundance of invasive species. The benefits of this method, such as increased ability to efficiently survey large areas and private lands, are identified and addressed. Limitations of the method, including surveyor bias, misidentification, and the lack of an area-based measurement, are also dealt with. The volunteer-collected data is compared to expert-collected data (the experts being state foresters and university employees) and a bias in regard to site selection was found. Despite the potential limitations, the method proves to be a useful tool for managers and researchers, and volunteer-collected data appears to be a viable option when funding and time limitations prevent experts from collecting the necessary data. The second paper explores the relationship between landscape characteristics, such as perimeter:area ratio and connectivity, and invasive species presence and abundance. Parcels of public woodlands throughout the state of Iowa were sampled for invasive species presence and abundance. Locations were mapped and, using GIS technologies, landscape characteristics were quantified. Based upon the results, no trends or relationships were evident. These results could indicate a lack of any relationship, but it is also possible that the absence of significant results could be due to a small sample size or a lack of sites representing the full spectrum of fragmentation (no or few relatively intact sites were sampled). Both papers are attempts to use tools (volunteers in the first and remote sensing in the second) that allow managers and researchers to study invasive species on a large scale that time or expense would otherwise prohibit. Further development of both techniques could greatly advance the fields of invasion ecology and land management.