Thesis
Is fine-scale fire disturbance better for insect populations?: Evaluating population growth rate in response to management plans for an endangered butterfly metapopulation
Washington State University
Master of Science (MS), Washington State University
2017
Handle:
https://hdl.handle.net/2376/102085
Abstract
Prescribed fire is used in fire-adapted ecosystems to reintroduce lost disturbance processes. Controlled burns create a mosaic of habitat features in the landscape for species endemic to these systems. Observed population responses of animals following disturbance are often described, but mechanistic population models that incorporate vital rates to understand and predict how spatially different fire regimes affect population dynamics are needed to develop optimal management scenarios. We assessed how an insect metapopulation responds to fire disturbance of varying spatial scales and intensity. Specifically, we test whether fine-scale disturbance increases population growth rate relative to large-scale burning, whether the response changes with fire intensity, and whether fine-scale disturbance decreases extirpation risk. In addition, we test whether eggs laid by immigrant butterflies relative to surviving residents are important drivers of population recovery post-fire. We tested seven management scenarios for an endangered butterfly, Fender's blue (Plebejus icarioides fenderi). We developed a spatially-explicit agent-based model for a metapopulation in Oregon, USA incorporating demographic vital rates, habitat-specific movement rules, and a dynamic effect of fire disturbance to quantify population dynamics and dispersal patterns for each scenario. Our approach of a spatially-explicit agent-based model demonstrated mechanisms by which fire-sensitive insect populations respond and recover from prescribed fires. Population recovery after fire in small populations is driven by immigrant individuals, and more intense disturbance generates extremes in population dynamics. We found fine-scale disturbance is better for population growth rate and large-scale disturbance increases extinction risk. Fire regimes should be applied at fine scales in the landscape to achieve boosts in population growth for rare, fire-sensitive insects.
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Details
- Title
- Is fine-scale fire disturbance better for insect populations?
- Creators
- Joseph Leroy Smokey
- Contributors
- Cheryl Barbara Schultz (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Sciences, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525396501842
- Language
- English
- Resource Type
- Thesis