Date of Award
Spring 5-3-2024
Level of Access Assigned by Author
Open-Access Thesis
Degree Name
Doctor of Philosophy (PhD)
Department
Ecology and Environmental Sciences
Advisor
Allison Gardner
Second Committee Member
Laura Kenefic
Third Committee Member
Amanda Klemmer
Additional Committee Members
Jessica Leahy
Cynthia Loftin
Abstract
Hard-bodied ticks (Acari: Ixodidae) are infectious disease vectors and their density and infection prevalence influence the spread of tick-borne pathogens that infect humans and wildlife. In forest ecosystems, tick lifecycle completion depends upon host availability (i.e., vertebrates ticks parasitize), and optimal off-host microclimate conditions. Forest management occurs across spatial scales (e.g., property, landscape), and whether it is the removal of trees from a property via timber harvesting or landscape fragmentation through land use change, this range of management affects tick and host habitat differently, with the potential to disrupt tick lifecycle stages. This dissertation examined, through a combination of observational field studies, laboratory pathogen detection assays, and a meta-analysis, how forest management across spatial scales initiates ecological cascades that impact wildlife and microhabitat with consequences for tick populations. Meta-analysis results showed reduced tick density but unaltered infection prevalence following prescribed burning and invasive vegetation removal; two types of local forest management practices. Too few studies existed to conduct a meta-analysis on the response of tick populations to timber harvesting. To address this knowledge gap, we examined forest structure on southern Maine properties with histories of timber harvesting, finding the number of trees per acre positively correlated to tick densities and key small mammal hosts’ population sizes and foraging behavior. Increased trees per acre correlated with stabilized microclimate temperature, reduced understory vegetation, and greater leaf litter depth, and these latter two variables best predicted increased tick densities in a random forest model. The relationship between timber harvesting and small mammal foraging behavior was a novel discovery and motivated further investigation of foraging at larger spatial scales. At the landscape scale, we hypothesized certain forest fragmentation metrics may reduce predator (e.g., coyote, fox) activity allowing for increased prey (i.e., small mammals) foraging, resulting in higher tick-host encounter rates and, consequently, higher tick densities. Forest patch isolation negatively correlated with the density of infected ticks, while patch edge density showed the opposite relationship. This work was the first to empirically document negative correlations between predator activity and prey foraging behavior, and, in turn, positive correlations between prey foraging behavior and the density of infected ticks. Overall, this dissertation shows how local and landscape scale land use change transforms surrounding habitat with consequences for tick densities. This research contributes to the greater understanding of tick ecology in changing forests, with implications for forest and wildlife management.
Recommended Citation
Hurd, Stephanie N., "The Effects of Forest Management Practices Across Spatial Scales on Tick Densities, Wildlife Communities, and Tick-Borne Pathogen Transmission" (2024). Electronic Theses and Dissertations. 3927.
https://digitalcommons.library.umaine.edu/etd/3927