Effects of Prescribed Fire in the Coastal Praries of Texas

Grace, James; Allain, Larry; Baldwin, Heather; Billock, Arlene; Eddleman, William; Given, Aaron; Jeske, Clint; Moss, Rebecca

Prescribed burning is widely applied, though in many circumstances the full range of its ecological effects is undocumented. This study provides an assessment of some of the effects of fire management in coastal grasslands in Texas. These studies were conducted primarily at the U.S. Fish and Wildlife Service (USFWS) Texas Mid-coast National Wildlife Refuge Complex (the TMC), though additional data from other locations in the region are also presented. There were four main components of this project: (1) a historical analysis of the role of fire in this ecosystem, (2) the development of standard methodology for assessing and monitoring fire effects in this system, (3) an evaluation of the effects of prescribed burning on the habitat being managed, and (4) an evaluation of the effects of burning on select fauna of special concern. Historical records suggest that both Native Americans and early Europeans contributed to widespread burning in the region and that settlement and the introduction of large cattle herds have been associated with reduced fires and increased shrub dominance. Data from a large number of burns shows that the response of the shrub eastern baccharis to fire is highly variable, but burning during the growing season and under drought conditions improves the chances of controlling baccharis. Chinese tallow was also found to be sensitive to burning, though complete control is largely restricted to small or isolated plants. Surveys of grassland birds found that LeConte’s sparrows were most commonly associated with prairies burned within the past two years, that Sedge wrens were most likely to be found in the 3-year-since-burn prairies, Savannah sparrows were most highly associated with 1-year-since-burn conditions, and swamp sparrows were equally likely to be found at any of the locations sampled. Rails were also monitored by using radio telemetry to evaluate their behavioral responses. Data collected in this fashion were used to estimate home range sizes and to gain insights into their potential behavioral responses to fires. Collection of sufficient data to draw broad conclusions about the direct mortality risk that fire poses to rails was not possible. Still, it is clear that rails have the capability to escape in some cases and to survive in the face of fire in others. While direct mortality from fire was not observed, indirect mortality that was due to predation was noted. Raptors attracted to fires were observed pursuing fleeing birds, and remains indicated that at least some rails were killed by predators in conjunction with burns. Overall, an average burn frequency of approximately every 3 years may be ideal for prairie habitat that is not badly overgrown with woody vegetation. Evidence suggests that part of the effect of burn frequency on habitat use is related to the density of herbaceous vegetation. Thus, variations in regrowth rates for vegetation may suggest either greater or lower burn frequencies for particular locations.

Effects of Prescribed Fire in the Coastal Praries of Texas

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