Last updated: May 21, 2024
Article
Terrestrial Vegetation Monitoring 2020 Data Summary for Cumberland Island National Seashore
Overview
Vegetation communities are dynamic entities influenced by environmental factors and impacts from natural and anthropogenic disturbances. The diversity of plants within the southeastern Coastal Plain contributes to a range of ecological services, provides habitat and resources to an array of wildlife, and functions as nature’s backdrop—usually the primary visual cue pulling us toward an appreciation of the outdoors. Determining trends in vegetation communities over time and identifying plant stressors is therefore vital to understanding the ecological health of terrestrial ecosystems within Southeast Coast Network (SECN) parks. Collectively, this information can be used to guide management actions that sustain a park’s ecological integrity and support plant conservation across a diversity of spatial scales for generations to come.
Methods
The Southeast Coast Network collects long-term data on terrestrial vegetation within its parks using a peer-reviewed protocol similar to other NPS Inventory and Monitoring networks in the eastern U.S. and is modeled after the approach used to describe natural vegetation in the Southeast developed by the Carolina Vegetation Survey. Permanent plots are used as the sample unit to determine a site’s (1) vascular plant richness and abundance for all native and non-native species; (2) basal area, density and health for all trees; (3) density of forest floor fuels; (4) community level disturbance events, including presence of insect pests and disease; and (5) abiotic condition (e.g., landform shape, soil nutrients, canopy coverage and height). Plots are randomly located across broadly defined habitat types within SECN parks. Our sampling effort focuses on dominant (> 30% coverage) habitat types within these parks, but when time and resources allow, the sampling effort is increased to include less dominant types. The 2019 Terrestrial Vegetation Monitoring protocol provides detailed descriptions of field and data processing techniques used by the Southeast Coast Network.
Study Area
Cumberland Island is the largest barrier island along Georgia’s coast, measuring 28.2 kilometers (17.5 miles) long and between 0.8–9.7 kilometers (0.5–6.0 miles) wide. The boundary of the National Seashore (CUIS) is 14,709 hectares (36,347 acres) and includes the main Cumberland Island, Little Cumberland Island to the north, and Drum Point Island in Cumberland River; over half of this area is owned and managed by the National Park Service. Typical vegetated habitats of Cumberland Island include graminoid-dominated foredunes, interdune meadows, scrub/shrub thickets, oak-dominated maritime forests, pine woodlands, and open salt marsh. This protocol was implemented for the first time within the park in 2020, and these data represent the baseline status of vegetation and associated abiotic elements from the following broadly defined habitats of the park: Coastal Plain Upland Open Woodlands, Maritime Open Upland Grasslands, and Maritime Upland Forests and Shrublands. Fifty-six plots were established across these habitats (see map).
Significant Findings
Site and Environmental Factors
Like the other barrier islands along Georgia’s coast, natural vegetation communities on Cumberland Island are strongly influenced by maritime-influenced tides, prevailing ocean winds and storms, and sedimentation from rivers. Strong storm events and highly saline environments affect the distribution of plants across the island, impacting the mosaic of marsh, forest, shrubland, and upland open grassland habitats. Furthermore, vegetation diversity is largely influenced by complex edaphic factors and their associated relationship with site hydrology and disturbance patterns (e.g., fire, storms). These wide-ranging environmental conditions were observed in the soil and disturbance data collected from vegetation plots. Most soils within these plots were acidic, although soils from Maritime Open Upland Grassland habitat plots were found to be slightly alkaline. A wide range of observable disturbances were documented in many of the plots within the island’s forested ecosystems, including windthrow, heavy browse by horses or deer, and signs of recent fire.
Vegetation
Two-hundred and thirteen plant species were observed across all plots, including 12 taxa not detected in previous plant surveys and six species listed as rare and tracked by the Georgia Department of Natural Resources. Overall plot level plant richness ranged from eight to 49 species, with trees, shrubs, and graminoids dominating Coastal Plain Upland Open Woodlands; herbs and graminoids dominating Maritime Open Upland Grasslands; and trees dominating Maritime Upland Forests and Shrublands.
Nonnative species were infrequent across all plots and broadly defined habitats surveyed during this monitoring effort. Two non-native species categorized as invasive by the Georgia Exotic Pest Plant Council were encountered in four different Maritime Upland Forest and Shrubland plots; these included chinaberry (Melia azedarach) and bahiagrass (Paspalum notatum). Maritime Forest and Shrubland habitats within the park typically had a tree canopy dominated by live oak (Quercus virginiana) and a sapling stratum dominated by saw palmetto (Serenoa repens) and rusty staggerbush (Lyonia ferruginea).
NPS photo / Elizabeth Rico
Other Findings
- 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.
- Live oak is the dominant tree-sized species across the island’s maritime forests (relative proportion among other woody species = 37%), but only represents less than 2% in the sapling and 14% in the seedling strata. Continued monitoring of these plots will help determine the degree of live oak regeneration trends on the island.
- All plots are scheduled to be resampled in summer 2024.
Full Report
The full report for Terrestrial Vegetation Monitoring at Cumberland Island National Seashore 2020 Data Summary
About the Southeast Coast Network
In 1999, the National Park Service initiated a long-term ecological monitoring program, known as “Vital Signs Monitoring,” to provide the minimum infrastructure to allow more than 270 national park system units to identify and implement long-term monitoring of their highest-priority measurements of resource condition. The overarching purpose of natural resource monitoring in parks is to develop scientifically sound information on the current status and long-term trends in the composition, structure, and function of park ecosystems, and to determine how well current management practices are sustaining those ecosystems.
The NPS Vital Signs Monitoring Program addresses five goals for all parks with significant natural resources:
- Determine the status and trends in selected indicators of the condition of park ecosystem,
- Provide early warning of abnormal conditions,
- Provide data to better understand the dynamic nature and condition of park ecosystems,
- Provide data to meet certain legal and Congressional mandates, and
- Provide a means of measuring progress towards performance goals.
The Southeast Coast Network (SECN) includes eighteen administrative areas containing twenty park units, fifteen of which contain significant and diverse natural resources. In total, SECN parks encompass more than 184,000 acres of federally-managed land across North Carolina, South Carolina, Georgia, Alabama, and Florida. The parks span a wide diversity of cultural missions, including four national seashores, two national historic sites, two national memorials, six national monuments, two national military parks, as well as a national recreation area, national battlefield, national historical park, and an ecological and historic preserve. The parks range in size from slightly more than 20 to nearly 60,000 acres, and when considered with non-federal lands jointly managed with the National Park Service, the network encompasses more than 253,000 acres.
For More Information
SECN Home Page
https://www.nps.gov/im/secn/index.htm
SECN Reports & Publications
https://www.nps.gov/im/secn/reports-publications.htm
About the NPS Inventory & Monitoring Program
https://www.nps.gov/im/index.htm
Data Downloads via the Natural Resource Information Portal
https://irma.nps.gov/Portal/