Terrestrial vegetation monitoring at Ocmulgee Mounds National Historical Park: 2021 data summary
Authors: Boyle M. 
Published: July 2023

The Southeast Coast Network (SECN) conducts long-term terrestrial vegetation monitoring as part of the NPS Inventory and Monitoring Program. The vegetation community vital sign is one of the primary-tier resources identified by SECN park managers, and monitoring is conducted at 15 network parks (DeVivo et al. 2008). Monitoring plants and their associated communities over time allows for targeted understanding of ecosystems within the SECN geography, which provides managers information about the degree of change within their parks’ natural vegetation. 2021 marks the first year of conducting this monitoring effort at Ocmulgee Mounds National Historical Park (OCMU). Eight vegetation plots were established throughout the park in early May. Data collected in each plot included species richness across multiple spatial scales, species-specific cover and constancy, species-specific woody stem seedling/sapling counts and adult tree (greater than 10 centimeters [3.9 inches {in}]) diameter at breast height (DBH), overall tree health, landform, soil, observed disturbance, and woody biomass (i.e., fuel load) estimates. This report summarizes the baseline (year 1) terrestrial vegetation data collected at Ocmulgee Mounds National Historical Park in 2021. Data were stratified across two dominant broadly defined habitats within the park, Coastal Plain Alluvial Wetlands and Coastal Plain Upland Forests. Noteworthy findings include: 142 vascular plant taxa (species or lower) were observed across eight vegetation plots, including 15 species not previously documented within the park. The most frequently encountered species in each broadly defined habitat included: Coastal Plain Alluvial Wetlands: Chinese privet (Ligustrum sinense), Chinese tallow (Triadica sebifera), Japanese honeysuckle (Lonicera japonica), eastern poison ivy (Toxicodendron radicans var. radicans), and smallspike false nettle (Boehmeria cylindrica). Coastal Plain Upland Forests: sweetgum (Liquidambar styraciflua), muscadine (Muscadinia rotundifolia var. rotundifolia), winged elm (Ulmus alata), water oak (Quercus nigra), loblolly pine (Pinus taeda), yaupon (Ilex vomitoria), Japanese honeysuckle, American beautyberry (Callicarpa americana), ebony spleenwort (Asplenium platyneuron), and multiple species of woody vines. Eleven non-native species invasive (Category 1 or Category 2) by the Georgia Exotic Pest Plant Council (GA-EPPC 2023) were encountered within the park during this monitoring effort. Three of these species—Chinese privet, Chinese tallow, and Japanese honeysuckle—were among the most frequent and abundant of all species observed within Coastal Plain Alluvial Wetland plots. There were no observations of vascular plant species listed as rare and tracked by the Georgia Department of Natural Resources (GADNR 2023) within these monitoring plots. Sweetgum, red maple (Acer rubrum), swamp tupelo (Nyssa biflora), and Chinese tallow were the most dominant species within the tree stratum of Coastal Plain Alluvial Wetland sites; water oak, loblolly pine, and sweetgum were the most dominant species of Coastal Plain Upland Forests. There were very few observable disturbances to natural and semi-natural vegetation communities documented during this monitoring effort, including very little to no impact of browsing by white-tailed deer, rooting by feral hogs, or presence of diseased or dying trees. The two most pronounced threats to native vegetation on the park are (1) the high prevalence of non-native, invasive plant species (particular within alluvial habitat, and (2) the altered hydrology of the park’s alluvial wetlands from conversion of large berms for vehicle and railroad traffic. Long-term monitoring data will aid in understanding how these threats over time impact the park’s forest communities.