Effects of Prescribed Burns on Small Mammal Populations with Comments on Houston Toad Populations

Abstract

Adaptive forest management has been an important tool to improve species diversity within a forest. Fire suppression and habitat fragmentation in Southern pine forests have resulted in habitat composition changes, potentially causing negative impacts on endemic species. Implementing prescribed fire helps restores the historic quality of the forest and effects can be monitored by indicator species. Bastrop State Park, home to the endangered Houston Toad (Bufo houstonensis) is located within the "Lost Pines" region of East Texas. Over the past 5 years, periodic burns have been conducted throughout the park. For my study, I conducted a small mammal survey to determine mammal diversity and relative abundance data in burned and unburned management units. The objectives of the study involve comparing diversity and relative abundance of small mammal (indicator species) and herptile populations between burned (2 trap lines) and unburned (2 trap lines) management units, assessment of vegetation differences between management units, evaluation of survivorship estimates using mark-recapture data, and the eventual incorporation of the results in evaluating habitat management for the Houston toad. Trapping was conducted from May 2005 until April 2006. Overall, 5 species of small mammals and 10 species of herptiles were collected. The white-footed mouse (Peromysucs leucopus) was the most commonly collected small mammal. A significant positive relationship (P = 0.0209) between body weight and body length was found in Peromyscus sp., however when compared between burned and unburned units, the relationship was non-significant (P = 0.3134). Small mammal monthly capture averages were greater in the burned units (P = 0.0073) however, survivorship estimates were non-significant between habitats. Finally, Houston toad size and herptile abundance did not vary between habitats. Small mammal abundance and diversity was influenced by vegetative composition among the burned and unburned units. Burned units had a greater percentage of seedling trees, shrubs, and herbaceous vegetation, likely leading to an increase in seeds and food availability. The results from my study show that low intensity prescribed fire slowly and effectively changes habitat composition and small mammal abundance and qualitative diversity. Fire has influenced the evolution of southern pine forests, with the animal species within the system consequently able to adapt to habitat changes. When implemented correctly, fire creates beneficial changes toward a more natural ecosystem regime for small mammal, herptile, and other forest species.