Vegetation Monitoring at Big Thicket National Preserve: Results for 2022

Carlson, Jane; Bracewell, Jeffrey

The Gulf Coast Inventory and Monitoring (I&M) Network completed its first round of vegetation monitoring in Big Thicket National Preserve between May and October 2022. Sixty plots were sampled across five of the Preserve's major units: Beech Creek, Big Sandy, Jack Gore Baygall, Lance Rosier, and Turkey Creek. Fifty-six of the plots were selected as a random draw within the entire area or major portions of each unit; these were the primary plots. Four additional plots, called targeted plots, were placed specifically in current or potential longleaf pine (Pinus palustris) restoration areas in Big Sandy, Lance Rosier, and Turkey Creek. All 60 plots were first visited during winter months between Dec. 2019 and Feb. 2022 to install plot markers and tag all trees that had a diameter at breast height [DBH] of ≥10 cm. Crews returned to sample plots during the growing season of 2022, following the methods published in the protocol “Monitoring Terrestrial Vegetation in Gulf Coast Network Parks”, and its 11 standard operating procedure documents (Carlson et al. 2018). In short, all plant species were identified in each 400-meter2 (20 x 20 meter) plot, and their coverages and relative frequencies were recorded in nested sampling frames as measures of understory dominance. New tree recruits were tagged, i.e., those reaching ≥10 cm DBH since plot establishment, and then all newly and previously tagged trees were assessed for damage. Juvenile trees were counted within four 10-m2microplots per full plot, divided into classes of seedlings (heights up to 1.36 m) and saplings (heights taller than 1.36 m and DBH <10 cm). These data served as a baseline for tracking forest health, including tree growth, recruitment, and mortality.