Effects of prescribed burning on a small mammal community in post oak savannah, Texas

Typescript (photocopy).The response of a community of small mammals to annual prescribed maintenance burning was examined in the post oak savannah vegetational type in Texas. The study was begun in the fall of 1982 before the second of a series of annual winter prescribed burning took place (at the end of February 1983) and terminated in the fall of 1983. The study tested the two hypotheses: i) burning would spatially alter the habitat structure and ii) the change in habitat structure would cause a redistribution of the populations of the small mammals in a manner which explains their habitat requirements. At least six species of small mammals were present on both the burned and unburned plots but only Siqmodon hispidus and Neotoma floridana were abundant and selective enough of habitat to allow appreciable evaluation of the degree and direction of response to change of habitat structure. Burning significantly reduced above-ground shrubby vegetative cover.' This reduction was accompanied by a sharp reduction in the abundance of Neotoma. The burning also reduced vegetative ground cover and, as a consequence the density of Sigmodon remained lower for most of the year following the burn. Neotoma had highest levels of abundance in those vegetative structures which had the highest amounts of shrubby cover and least amounts of grass. The distribution of Sigmodon was the reverse of that of Neotoma. After ground cover, consisting mainly of perennial grasses, was restored in the burned portions of the burned grid, Sigmodon reutilized those portions at a level similar to that recorded pre-burn. Significant shrubby cover was not established on the burned portions and those portions were not utilized by Neotoma during the entire post-burn study period. Methods of assessment of the vegetative structures were the same for burned and unburned grids, and the animals responded similarly to similar vegetative attributes between the grids. Therefore, I conclude that for the period of this study, burning was the proximate factor while resulting vegetative structures were the ultimate factors affecting the distribution of the animals. I further maintain that a system of annual prescribed burning will reduce drastically the abundance of brush and, as a consequence, that of Neotoma. As ground cover decreases and then increases in the course of time following a burn, the burn will maintain a moderate cyclic pattern of abundance for Sigmodon..