Thesis
The effects of nearshore forest thinning on upland habitat use by pond-breeding amphibians in a montane coniferous forest
Washington State University
Master of Science (MS), Washington State University
05/2020
DOI:
https://doi.org/10.7273/000004116
Handle:
https://hdl.handle.net/2376/125315
Abstract
Forest thinning removes woody fuels from coniferous forests in a way that mimics historic wildfire regimes by removing mid-story pines and increasing horizontal and vertical spacing. Thinning results in few long-term effects to habitat features required by sensitive amphibians including canopy cover, soil moisture and available cover objects. Though some research suggests minimal effects of thinning to amphibians, few studies have assessed effects to aquatic-breeding amphibians in forests of the Pacific Northwest. We conducted an experimental study evaluating effects of understory thinning on aquatic-adjacent habitat on forest conditions and amphibian movement patterns. Thinning treatments were implemented in 12 plots, alternating with matching controls, in the pine-fir forests surrounding Big Lake, a 10.7 ha ephemeral lake in northern California. We assessed effects of thinning on habitat variables relevant to amphibians and used pitfall traps to assess movement by long-toed salamanders (Ambystoma macrodactyllum), western toads (Anaxyrus boreas), and Pacific chorus frogs (Pseudacris regilla). We investigated associations between amphibian captures and upland habitat conditions and assessed amphibian use of debris piles created during treatments. We predicted metamorphic amphibians would seek cover and shade in control plots, while adults would find migration easier in treated plots. Tree density decreased while woody debris cover showed a moderate increase after treatments. A modest increase in captures of chorus frogs occurred in treatment plots, but no treatment effect was detected for toads or salamanders. Receding surface waters forced salamander larvae to develop and emerge at the eastern end of Big Lake. With a shorter development time, western toads and chorus frogs were able to emerge from the pond before surface waters receded. Salamanders and chorus frogs were captured in areas of high leaf litter and low tree density, suggesting a preference of these species for foraging in lower intensity forests. Foraging diurnally, toads preferred areas offering high levels of canopy cover. Our results suggest moderate understory thinning in forests adjacent to aquatic habitat may show no harmful short-term impacts to pond-breeding amphibians. No amphibians were found under debris piles; future research should survey such piles during different times of year and directly before burning.
Metrics
Details
- Title
- The effects of nearshore forest thinning on upland habitat use by pond-breeding amphibians in a montane coniferous forest
- Creators
- Andrew Holt McIntyre
- Contributors
- Jonah Piovia-Scott (Advisor) - Washington State University, Biological Sciences, School of
- 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
- Identifiers
- 99900890784901842
- Language
- English
- Resource Type
- Thesis