Date of Award
Program or Major
Natural Resources and Environmental Studies
Doctor of Philosophy
Russell G Congalton
Habitat modification has become a progressively important concern as human populations increase and urbanization continues to replace natural environments with anthropogenic landscapes. Habitat modification concerns both the loss and fragmentation of environments, and these actions can have profound effects on ecosystem function, including increasing the potential of invasion by exotic species in vulnerable landscapes. The Coastal Watershed of New Hampshire (NH) has seen a 52% growth in population over the last 30 years which has led to marked urbanization and land use change. However, little has been done to study current land cover types, levels of fragmentation, and how fragmentation might be affecting the spread of woody invasive species. This research investigated new ways of using remote sensing techniques, such as object-based image analysis (OBIA) and multi-temporal image analysis, to create accurate land cover maps and corresponding fragmentation metrics. These products were then used to determine if habitats of interest in the Coastal Watershed were potentially more susceptible to invasion by woody invasive species.
To map the Coastal Watershed, new sampling protocols were designed and implemented for labeling forest types on Landsat 5 Thematic Mapper (TM) imagery. In classification, an OBIA approach, coupled with the multi-temporal analysis, performed better than creating maps using a single Landsat 5TM image. A new fragmentation program, PolyFrag was also created to compute fragmentation metrics from the vector land cover maps generated by the OBIA approach. Finally, The Nature Conservancy (TNC) woody invasive species data were used along with the PolyFrag fragmentation maps to create a predicted probability map of the presence of woody invasive species. When compared to other programs, PolyFrag performed equally well to the more prevalent FRAGSTATS program in creating a predictive model from fragmentation metrics. However, the advantage of PolyFrag over FRAGSTATS is that it creates a fragmentation map in addition to the patch, class, and landscape metrics. Interestingly, both predictive models indicated that woody invasive species were less likely to be found in deciduous forests than in either coniferous or mixed forests. The maps and methods designed in this research are useful for fragmentation and invasive species management.
MacLean, Meghan Graham, "A multi-temporal image analysis of habitat modification in the Coastal Watershed, NH" (2012). Doctoral Dissertations. 698.