Abstract. We compared the effects of late dormant‐season and late growing‐season prescribed fires on herbaceous species in restored shortleaf pine‐ (Pinus echinata) grassland communities in the Ouachita Highlands of western Arkansas. Herbaceous species richness, diversity, and total forb and legume abundance increased following fire. Late growing‐season burns reduced distribution and abundance of panicums (primarily Panicum boscii, P. dichotomum, and P. linearifolium) while late dormant‐season burns increased Panicum distribution and abundance. Density of legumes (such as Stylosanthes biflora) increased following frequent or annual dormant‐season fires. However, season of fire influenced the distribution and abundance of fewer than 10 % of the species. Fire plays an essential role in pine‐grassland communities by creating and maintaining open canopy conditions that perpetuate understory herbaceous plant communities.
Pine forests of southeastern United States have been burned primarily in the dormant season to accomplish silvicultural objectives, but with increased emphasis on ecosystem restoration fires are now prescribed in other seasons. We observed fire behavior during both growing season and dormant season prescribed fires in shortleaf pine ( Pinus echinata ) stands managed as pine-grassland communities for the endangered Red-cockaded Woodpecker ( Picoides borealis ). Fuel beds for dormant season fires were characterized by lower amounts of live fuels, higher amounts of 1-hr time lag fuel and a greater total fuel load than growing season fires. Fuel consumption and percent of the total fuels consumed was greater in dormant season fires than in growing season fires. Fireline intensity, heat per unit area, reaction intensity, and rate of spread were greater in dormant season fires than in growing season fires. Lower fire intensity in growing season fires was possibly a function of lower amounts of 1-hr time lag fuels, higher amounts of live herbaceous fuels, and possibly a less porous fuel bed. Additionally, growing season fires had lower heat per unit area and reaction intensity and slower rates of spread. The Keetch-Byram drought index (KBDI) did not provide a good index for potential fire behavior on our drought-prone sandy loam soils. KBDI during growing season fires averaged over four times greater than during dormant season fires, but fire intensity was greater in dormant season fires. Low KBDI values may be misleading and give a false sense of security for dormant season fire prescriptions on sandy loam soils because the duff layer may dry more quickly as a result of inherent low water holding capacity. High KBDI values may result in prescribed burns being canceled because of conditions that are erroneously perceived to be outside the prescription window. We caution against over-reliance on KBDI as a determining factor for conducting prescribed burns on areas with sandy or sandy loam soils.
Population trend data indicates the Henslow's Sparrow (Ammodramus henslowii) is declining. Little information is available on the status, distribution, and habitat requirements of this species during winter. We obtained winter density estimates of Henslow's Sparrows and quantified and compared habitat structure along transects occupied and unoccupied by birds in longleaf pine (Pinus palustris) forests in westcentral Louisiana. We flushed Henslow's Sparrows from 14 transects during four surveys of 48 20-X 100-m transects from January to February 1996, and 20 transects during four surveys of 46 of the same transects from December 1996 to February 1997. The range of Henslow's Sparrow densities for both survey periods combined was 0.0-13.8 birds/ha (median = 0.0, 75th percentile = 1.3, 95th percentile = 5.0). We used logistic regression to evaluate the association of vegetative structure with Henslow's Sparrow habitat use. The most parsimonious model included litter depth and herbaceous cover as habitat variables predictive of Henslow's Sparrow occurrence. The model correctly classified the occupancy status of 79% (52 of 66) of observed transects. The number of Henslow's Sparrows observed in transect surveys declined with increased number of growing seasons since the last burn, suggesting fire may influence habitat quality.
Synthesis of multiple sources of fire history information increases the power and reliability of fire regime characterization. Fire regime characterization is critical for assessing fire risk, identifying climate change impacts, understanding ecosystem processes, and developing policies and objectives for fire management. For these reasons, we conducted a literature review and spatial analysis of historical fire intervals in Texas, USA, a state with diverse fire environments and significant fire-related challenges. Limited literature describing historical fire regimes exists and few studies have quantitatively assessed the historical frequency of wildland fire. Written accounts provided anecdotal fire information that is spatially and temporally constrained. Three spatial datasets depicting historic mean fire intervals (MFIs) showed agreement in that the majority of Texas consisted of frequent fire regimes (MFIs = 1 yr to 12 yr), and that a gradient of decreasing fire return intervals existed from west to east. Much potential likely exists for acquiring fire history data in the Piney Woods region, the Oak Woods and Prairies region, and the mountain ranges of the Trans Pecos region. These data will be valuable for improving fire regime characterization to guide fire planning and budget processes, for the restoration and maintenance of fire-adapted landscapes, and for informing fire prevention and education activities.
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