Date of Award
Master of Science - Environmental Sciences
Dr. Brian Oswald
Dr. Kenneth Farrish
Dr. Rebecca Kidd
Dr. Yuhui Weng
Longleaf pine (Pinus palustris) savannas were once dominant in East Texas and parts of western and central Louisiana. Native understory species have since been removed or reduced by exotic plants that were introduced and from the reduction in the frequency of both wild and prescribed fires. A diverse layer of understory species can still be seen today, but not often in the historical savanna setting that is desirable in longleaf pine ecosystems. This project aimed to identify site characteristics associated with longleaf ecosystems that support a dense, herbaceous understory with little to no midstory cover.
A total of 65 plots were established within the Boykin Springs Area to evaluate the influence of overstory cover, basal area, aspect, elevation, and slope on the number of plant genera. The study area was divided into three sites (A, B, and C) which had differing vegetative parameters and site characteristics such as elevation and slope. Site A had been recently burned as it has and is currently being managed for Red-cockaded Woodpecker habitat. The vegetative parameters and site characteristics had significant effects on the number of plant genera found in those sites.
Six of the plots were confirmed to be on Letney soils and were evaluated for their general soil parameters (sand, silt, and clay content). Equipment used to
define understory and overstory parameters were the spherical densiometer for measuring overstory canopy cover, 1 m² pvc pipe frame for percent cover by growth form, and vinyl measuring tape for little bluestem cover. Due to the small sample size, these plots were not included in the data analysis for the three study sites. These plots were only utilized for their general soil parameters and vegetative composition. Soil texture and series did not have any significant effects on the number of genera on those plots.
Based on the Pearson Correlation method, the number of genera per plot increased with elevation and slope (P=0.0044 and 0.0212, R=0.372 and 0.30207, respectively). This can also be explained by the negative correlation between elevation and both the overstory cover and the basal area (P=0.0918 and 0.0983, R= -0.225 and -0.221, respectively). As elevation increased, there was a decline in basal area and overstory cover which leads to a more diverse, understory layer. Results from this study suggest that in order to promote or restore a diverse, herbaceous understory in historical longleaf pine savannas, efforts to plant specific understory species that are important in restoration efforts should be aimed at areas with open canopy conditions and on slopes with greater solar exposure.
McCalip, Brooke, "Characterization of Sites for Native Herbaceous Understory Restoration in West Gulf Coast Longleaf Pine (Pinus palustris) Savannas" (2018). Electronic Theses and Dissertations. 209.
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