THE INFLUENCE OF FIRE ON LEPIDOPTERAN ABUNDANCE AND COMMUNITY STRUCTURE IN FORESTED HABITATS OF EASTERN TEXAS

Abstract

Transect surveys were used to examine the influence of tire on lepidopteran communities (Papilionoidea and Hesperioidea) in forested habitats in eastern Texas. Lepi- dopteran abundance was greater in pine forests where prescribed tire maintained an open mid and understory compared to forests where fire had less impact on forest structure. Ahun- dance of nectar sources paralleled this pattern of abundance. Taxonomic groups of Lepidop- tera varied across forest types in patterns coincident with their dependence on nectar sources and tendency to tly in shaded habitats. Historically, forests of the West Gulf Coastal Plain were strongly influenced by fire ignited by lightning or Native Americans (Komarek 1964; 1974; Harcombe et al. 1993; Frost 1993; 1998; Platt 1999). During the mid and late 1900s wildfires have been increasingly sup- pressed and replaced, to a limited extent, by prescribed fire (Frost 1993; Platt 1999). Differences in frequency, intensity and timing of prescribed fire, compared to wildfire, have resulted in a dramatic alteration of West Gulf Coastal Plain forest structure. The most obvious visible change has been the massive encroachment of woody midstory vegetation in upland forests on most of the forested landscape (Frost 1993; Platt 1999). Resulting competition has eliminated much of the diverse herbaceous community, especially in the longleaf pine savannahs that once occupied these sites (Bridges & Orzell 1989; Outcalt & Outcalt 1994). These changes in community structure have significantly altered the forested ecosystems of the region and contributed to changes in species abundance patterns of both plants and animals. Numerous species adapted to the fire-maintained communities that existed prior to Euro- pean colonization are now of conservation concern due, in part, to declining abundance as a consequence of changes in the fire regime (Conner et al. 1989; Rudolph & Burgdorf 1997).