Date of Award
Master of Science (MS)
Plethodon salamanders may serve as important indicators of forest ecosystem integrity due to their niche, physiological sensitivity, abundance, site fidelity, and association with forest structures. Forest ecosystems provide direct and indirect services and products that benefit society. Monitoring the quality and status of these direct and indirect use values is important to manage and maximize the benefit to people. An ecological indicator is something that may indicate the state of a system. Indicators are widely used in a variety of fields including forestry, economics, and environmental management to monitor the state of desired systems. The IndVal method is a statistical analysis used to determine the efficacy of a species as an indicator species, by determining the association between the species of interest and site groups or habitats. I sought to determine if the red-backed salamander is an indicator of forests based on the IndVal method, and if the red-backed salamander may be used as an indicator of use values. I hypothesized that red-backed salamanders may be used as an indicator of standing mature forested areas. I hypothesized that salamander abundance would be highest in forested areas and may act as an indicator species of forest habitats. I hypothesized that red-backed salamander abundance would have a positive correlation with indirect use values and a negative correlation with direct use values.
The study area consisted of Forestland, Timberland, and Agriculture land-uses within northwestern Pennsylvania. I used visual encounter surveys and drift fences for capturing of red-backed salamanders (Plethodon cinereus) for abundance estimates. Visual encounter surveys were done within area constrained (10x10m) plots and a time constraint of roughly 30 minutes. I measured environmental variables within each plot. An N-mixture model of P. cinereus was used to estimate abundance based on repeated counts data. I used a principal components analysis (PCA) to determine which environmental variables were associated with study sites. I used a Kruskal-Wallis test and post-hoc Dunn’s test to determine differences between land-use in red-backed salamander abundance. I applied the IndVal method to red-backed salamander abundance in association to land-use and habitat. I estimated indirect use values through cost replacement methods for water purification, water cycling production, nitrate treatment, and soil erosion. I obtained direct use values through land-owners and the U.S. Forest Service archives, which the cost of production and gross value of production were used to determine the net and gross value. I used a Spearman’s Rank correlation to determine the relationship between red-backed salamander abundance and the direct and indirect use values of land-uses. The PCA 1 axis described an environmental gradient of closed to open canopy. Forestland sites had the lowest sunlight values, Agriculture having the highest, and Timberland intermediate between the two. Canopy percent cover was the most informative variable in the N-mixture model. Red-backed salamander abundance was greatest, mean = 434, on Forestland sites and was significantly (p-value <0.05) different from Timberland and Agriculture. The red-backed salamander was highly associated with Forestland with an indicator species value of 0.876, and 0.972 for forests. Red-backed salamanders held a significant strong positive relationship with indirect use values, rho = 0.84. P. cinereus abundance had a significant strong negative relationship with gross direct use values, rho = -0.95, and net direct use values, rho = -0.92. The strong correlation between P. cinereus abundance and indirect use values suggest that red-backed salamander abundance may have applications as an indicator of indirect use values for forest ecosystems.
Garbark, Christopher, "The Relationship of Red-Backed Salamander Abundance to the Direct and Indirect Use Value of Undisturbed Forest, a Timberland Mosaic of Forest, and Agricultural Land-Uses" (2019). Theses and Dissertations (All). 1691.