Terrestrial vegetation monitoring at Cumberland Island National Seashore: 2020 data summary

Abstract

The Southeast Coast Network (SECN) conducts long-term terrestrial vegetation monitoring as part of the nationwide Inventory and Monitoring Program of the National Park Service (NPS). The vegetation community vital sign is one of the primary-tier resources identified by SECN park managers, and it is currently 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. 2020 marks the first year of conducting this monitoring effort at Cumberland Island National Seashore (CUIS). Fifty-six vegetation plots were established throughout the park from May through July. 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 Cumberland Island National Seashore in 2020. Data were stratified across three dominant broadly defined habitats within the park, including Coastal Plain Upland Open Woodlands, Maritime Open Upland Grasslands, and Maritime Upland Forests and Shrublands. Noteworthy findings include: 213 vascular plant taxa (species or lower) were observed across 56 vegetation plots, including 12 species not previously documented within the park. The most frequently encountered species in each broadly defined habitat included: Coastal Plain Upland Open Woodlands: longleaf + pond pine (Pinus palustris; P. serotina), redbay (Persea borbonia), saw palmetto (Serenoa repens), wax-myrtle (Morella cerifera), deerberry (Vaccinium stamineum), variable panicgrass (Dichanthelium commutatum), and hemlock rosette grass (Dichanthelium portoricense). Maritime Open Upland Grasslands: wax-myrtle, saw greenbrier (Smilax auriculata), sea oats (Uniola paniculata), and other forbs and graminoids. Maritime Upland Forests and Shrublands: live oak (Quercus virginiana), redbay, saw palmetto, muscadine (Muscadinia rotundifolia), and Spanish moss (Tillandsia usneoides) Two non-native species, Chinaberry (Melia azedarach) and bahiagrass (Paspalum notatum), categorized as invasive by the Georgia Exotic Pest Plant Council (GA-EPPC 2018) were encountered in four different Maritime Upland Forest and Shrubland plots during this monitoring effort. Six vascular plant species listed as rare and tracked by the Georgia Department of Natural Resources (GADNR 2022) were observed in these monitoring plots, including the state listed “Rare” Florida swampprivet (Forestiera segregata var. segregata) and sandywoods sedge (Carex dasycarpa) and the “Unusual” green fly orchid (Epidendrum conopseum). Longleaf and pond pine were the most dominant species within the tree stratum of Coastal Plain Upland Open Woodland habitat types; live oak was the most dominant species of Maritime Upland Forest and Shrubland types. Saw palmetto and rusty staggerbush (Lyonia ferruginea) dominated the sapling stratum within Maritime Upland Forest and Shrubland habitat types. Of the 20 tree-sized redbay trees measured during this monitoring effort only three were living and these were observed with severely declining vigor, indicating the prevalence and recent historical impact of laurel wilt disease (LWD) across the island’s maritime forest ecosystems. There was an unexpectedly low abundance of sweet grass (Muhlenbergia sericea) and saltmeadow cordgrass (Spartina patens) within interdune swale plots of Maritime Open Upland habitats on the island, which could be a result of grazing activity by feral horses. Live oak is the dominant tree-sized species across...