Year of Award

2011

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Fish and Wildlife Biology

Department or School/College

College of Forestry and Conservation

Committee Chair

Winsor Lowe

Commitee Members

Creagh Bruener, Lisa Eby, Vanessa Ezenwa, L. Scott Mills

Keywords

amphibian, disease, forest management, parasite, wetland, wildfire

Abstract

Climate-driven changes in wildfire and other disturbance regimes are expected to affect populations and communities worldwide. Understanding how these changes will affect native species is critical for future conservation efforts, especially on managed forests. Using data from several wildfires that burned between 1988 and 2003 in and next to Glacier National Park, Montana, I examined how fire affected the distribution, abundance, and infection status of 3 native amphibians. In Chapter 1, I used long-term data on wetland occupancy to show the long-toed salamander (Ambystoma macrodactylum) and Columbia spotted frog (Rana luteiventris) were resistant to change during the first 6 years after wildfire, but declined over longer time periods in areas of high-severity fire. In contrast, boreal toad (Anaxyrus boreas) occupancy increased greatly during the 3 years after wildfire burned low-elevation forests, followed by a gradual decline. In Chapter 2, I measured how the interaction of stand-replacement wildfire and forest management affected amphibian abundance and 2 nematodes that infect amphibians. Population size of salamanders was negatively related to fire severity, with stronger effects on populations that were isolated or in managed forests. These effects were not evident in the abundance of the nematode Cosmocercoides variabilis. Population size of spotted frogs increased weakly with burn extent in managed and protected forests, a pattern that was reflected in the greater infection intensity of the mutualistic nematode Gyrinicola batrachiensis. In Chapter 3, I investigated how environmental variation and habitat use affects the probability that boreal toads had chytridiomycosis, a disease linked with amphibian declines worldwide. Probability of infection was lower for toads captured terrestrially than aquatically, and was lower for toads captured in recently burned habitats compared with unburned habitats. Simulations showed that spatial variation in infection, like that related to habitat use in a heterogeneous landscape, could significantly reduce the risk of metapopulation decline. Collectively, my results underscore the importance of measuring individual-, population-, and community-level responses across a range of disturbances and in both managed and protected forests. These results will provide scientists and land managers a greater understanding of the long-term effects of wildfire on local amphibians and other native species.

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© Copyright 2011 Blake Roger Hossack