Terrestrial Vegetation Monitoring at Cape Hatteras National Seashore: 2023 Data Summary—Cycle 2 and Newly Established Cycle 1 Plots

Boyle, M.; Davis, Mallorie

doi:10.36967/2317710

Parks within the Southeast Coast Network (SECN) support diverse terrestrial vegetation communities, and long-term monitoring is essential for detecting trends and assessing ecosystem condition. Vegetation within SECN parks is sampled using 20 × 20 meter (65.6 × 65.6 ft) plots. This report summarizes vegetation status at Cape Hatteras National Seashore in 2023, representing the second monitoring cycle following baseline data collection in 2019. In 2019, 52 plots were established across four habitat types—nontidal wetlands, tidal wetlands, upland forests, and upland open grasslands—and four management units: Bodie Island, North Hatteras Island, South Hatteras Island, and Ocracoke Island. All plots were resampled in 2023, and 19 additional plots were established, increasing the total sample size to 71. Across all plots, 294 vascular plant taxa were documented, including 21 taxa not previously recorded in park species lists, including the invasive Rosa multiflora. Nineteen taxa are designated as rare within North Carolina, including two state-threatened species: blue witchgrass (Dichanthelium caerulescens) and Gulf Coast spikerush (Eleocharis cellulosa). Live tree basal area (m²/ha) increased between 2019 and 2023 for all species except swamp bay (Persea palustris) in upland forest plots. Within the South Hatteras Island unit, 25% of swamp bay individuals classified as alive in 2019 were dead in 2023, and an additional 50% exhibited severe decline or were functionally dead. Observed symptoms are consistent with laurel wilt disease, a fungal pathogen vectored by an invasive ambrosia beetle that has caused extensive mortality of Lauraceae species across the southeastern United States. Aside from impacts associated with laurel wilt disease, very few widespread disturbances and threats were detected within sampled plots in 2023. A vegetation health scorecard was developed for each management unit and habitat type. Invasive plant species occurred across all habitats, representing a consistent stressor; however, native species diversity was rated as “Good” across all monitored habitats. Despite ongoing coastal development and accelerating rates of sea-level rise, Cape Hatteras National Seashore continues to function as a protected refuge for diverse plant assemblages along the Outer Banks of North Carolina.

Terrestrial Vegetation Monitoring at Cape Hatteras National Seashore: 2023 Data Summary—Cycle 2 and Newly Established Cycle 1 Plots

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