Preliminary vegetational changes in frequently burned and unburned upland pine-hardwood forests at Cook’s Branch Conservancy in Montgomery County, Texas, U.S.A.

Abstract

Vegetational changes over a 6-year period (2012 to 2017) were recorded in upland pine – hardwood forests on Cook’s Branch Conservancy (CBC) in Montgomery County, Texas, using permanent vegetation monitoring plots as a basis for following future vegetational changes. Cook’s Branch Conservancy is a 2,160-hectare preserve purchased by George and Cynthia Mitchell in 1964 and is now part of a conservation program operated by the Cynthia and George Mitchell Foundation. Plots sampled for this study include eight Fire Monitoring Handbook vegetation plots located in upland forests over sandy soils including four plots located in frequently burned stands (11 times since 2002) and four plots located in stands that have not been burned in decades (20+ years). Data collected confirm significant changes to vegetational structure in frequently burned forests compared to similar habitats that are unburned. Prior to initiation of prescribed burning in 2001, habitat conditions and species composition was similar in stands surrounding all eight plots sampled. The overstory tree structure of all eight plots sampled is similar in basal area, canopy cover, and in species composition. The number of midstory trees is less in frequently burned plots, however, frequently burned plots possess a much greater number of seedlings. At the shrub level, Callicarpa americana and Ilex vomitoria represented 97.7% of total stems in the frequently burned plots, with Callicarpa americana stems count increasing in frequently burned plots, suggesting the species is pyrophytic. Additionally, diversity of herbaceous species was higher in frequently burned plots vs unburned plots. Visually, the frequently burned forest is open in the understory, while the unburned forest is dense with woody understory vegetation making it difficult to traverse on foot.