Student Research Paper
David M. Bowne
Human activity causes landscape changes, which in turn can influence habitat fragmentation and a loss of habitat connectivity. The purpose of this project was to evaluate temporal changes in landscape heterogeneity on potential habitat availability and accessibility for the painted turtle, Chrysemys picta. We hypothesized that the number of freshwater ponds has increased and that the landscape between freshwater ponds has become more heterogeneous from the 1960s to 2016 in Lancaster County, Pennsylvania. We obtained historical wetlands and land use data from the 1950s to 1970s as well as wetlands and land use data from 2011 to 2016 to show the relationship between freshwater ponds and their surrounding landscape matrix. A buffer of 1500 meters around 12 ponds was used to create 12 landscape replicates. These replicates were then analyzed for several measures of landscape division in FRAGSTATS, including the number of patches, patch density, and Landscape Division Index. The total number of ponds in each landscape at each time period was also determined in ArcGIS. Statistical analyses using paired t-tests showed that there were a greater number of patches (p = 4.47e-10), greater patch density (p = 3.63e-10), and a greater proportion of divided landscape (p = 1.57e-05) in the 2011-2016 data compared to the 1950s-1970s data. The data showed that the number of ponds increased in the entire landscape during the same period. These analyses show that in Lancaster County, the landscape has become more heterogeneous over the course of approximately 60 years, leading to a more divided landscape. These results have implications for animals, such as the painted turtle, that rely on pond connectivity as a component of their habitat. Although the number of habitat patches has increased, increased landscape heterogeneity could lead to decreased habitat connectivity, which could negatively affect organisms by preventing them from using all of the potential habitat in the landscape.
DiBiase, Elizabeth, "Evaluating Temporal Changes in Landscape Heterogeneity as an Influence on Freshwater Turtle Habitat in Lancaster County, Pennsylvania" (2018). Biology: Student Scholarship & Creative Works. 2.