Last updated: May 21, 2024
Article
Terrestrial Vegetation Monitoring 2021 Data Summary for Congaree National Park
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 Terrestrial Vegetation Monitoring Protocol provides detailed descriptions of field and data processing techniques used by the Southeast Coast Network.
Study Area
Congaree National Park is located within the inner Coastal Plain of South Carolina, approximately 30 kilometers (18.6 miles) southeast of the state capital, Columbia. The park protects the largest remaining contiguous tract of old-growth bottomland forest in the United States and has been designated as an International Biosphere Reserve, National Natural Landmark, Globally Important Bird Area, Ramsar Wetland of International Importance, and (in part) Wilderness Area. Most of the park is in the vast floodplain of the Congaree River, providing a diverse assembly of bottomland tree species and forest community types. In addition to its bottomland forests, the park supports upland pine-dominated woodlands along its northern boundary. This monitoring protocol was implemented for the first time at the park in 2021, and these data represent the baseline status of vegetation and associated abiotic elements from the following broadly defined habitats of the park: Coastal Plain Alluvial Wetlands and Coastal Plain Upland Open Woodlands. Sixty-four plots were established across these habitats (see map).
Significant Findings
Site and Environmental Factors
The high level of woody plant biodiversity within the floodplain of Congaree National Park can be attributed to two factors. First, the complex geomorphology of the floodplain produces a multitude of elevation gradients often occurring over small spatial scales providing a continuum for species with varying tolerances of flooding. Second, wind events at large and small scales promote regeneration of shade intolerant (and often less hydric) woody plants by creating canopy gaps which bring light and alter the soil moisture of the forest floor. Upland habitats of the park were historically maintained by frequent, low severity fires that created open spaces between canopy trees and maintained high levels of plant biodiversity. These wide-ranging environmental conditions were observed in the soil and disturbance data collected from vegetation plots. A wide range of observable disturbances were documented in many of the plots within the park’s forested ecosystems, including windthrow, rooting by feral hogs, and signs of recent and historic fire.
Vegetation
Two-hundred and ninety-five plant species were observed across all plots. This included 37 taxa not detected in previous plant surveys and four species listed as rare and tracked by the South Carolina Natural Heritage Program. Overall plot-level plant richness ranged from six to 72 species, with trees and herbs providing most of the diversity to both Coastal Plain Alluvial Forests and Coastal Plain Upland Open Woodlands.
Non-native species were fairly frequent across all plots and broadly defined habitats surveyed during this monitoring effort. Seven non-native species, categorized as invasive by the South Carolina Exotic Pest Plant Council, were encountered on the park during this monitoring effort; these included sweet autumn virginsbower (Clematis terniflora), Chinese privet (Ligustrum sinense), Japanese honeysuckle (Lonicera japonica), Japanese climbing fern (Lygodium japonicum), Japanese stilt grass (Microstegium vimineum), marsh dew flower (Murdannia keisak), and Chinese wisteria (Wisteria sinensis).
Other Findings
- Feral hog rooting was observed in 73% of the Alluvial Vegetation plots.
- The most dominant tree species within Alluvial Vegetation plots were sweetgum (Liquidambar syraciflua), water tupelo (Nyssa aquatica), green ash (Fraxinus pennsylvanica), and bald-cypress (Taxodium distichum); the most dominant species in Upland Open Woodland plots was loblolly pine (Pinus taeda).
- More than 25 unique species of sedge (Carex sp.) were observed at Congaree National Park during this monitoring effort.
- All plots are scheduled to be resampled in summer 2025.
Full Report
Terrestrial Vegetation Monitoring at Congaree National Park 2021 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/