Conservation biology: Theoretical considerations and practical applications

Conservation biologists and wildlife managers are frequently charged with making important decisions pertaining to the viability of species, communities, and ecosystems despite considerable uncertainty surrounding the consequences of various management actions. Mathematical models have become increasingly popular among conservation biologists due to their ability to explore these uncertainties as well as offer quantitative predictions of species viability. This dissertation consists of two manuscripts (chapters 1 and 2) covering theoretical and practical issues related to the use of stochastic matrix models in conservation biology. A third manuscript (chapter 3) consists of a modeling application related to a hypothetical wolf reintroduction to Olympic National Park, Washington.; Chapter 1 examines estimates of extinction risk using structured and unstructured density independent population models. An analytical diffusion approximation is used to derive a rule of thumb that extinction estimates are reliable for time horizons of 1/5 to 1/10 N, where N is the number of transition estimates or population counts used to parameterize the model. Chapter 2 reviews applications of stochastic matrix models to problems in conservation, with a focus on the methods used to formulate and analyze models. The performance of different analytical methods is compared via simulation studies. In addition, a simulation study is conducted to examine the potential gain in precision obtained from incorporating covariates into stochastic matrix models. Finally, chapter 3 contains a modeling application to assess the impact of a hypothetical wolf reintroduction on elk population dynamics in Olympic National Park. Simulations incorporating a wide range of parameter and system uncertainty are used to conduct a formal sensitivity analysis of percent changes in elk population size. These results are used to assess the importance of parameter and system uncertainty on elk population dynamics.