Vegetation Monitoring at Chattahoochee River National Recreation Area: The 2021 Baseline

Plant communities change with the environment and with disturbances natural and human. In the Southeast's Coastal Plain and Piedmont, plant diversity underpins ecological services, supports wildlife and forms the scenery that draws people outdoors. Tracking how vegetation changes, and what stresses it, is therefore central to understanding the health of land ecosystems in the parks of the National Park Service's Southeast Coast Network — and to guiding management that sustains them.

How the network monitors vegetation

The network follows a peer-reviewed protocol similar to other eastern Inventory and Monitoring networks and modeled on the Carolina Vegetation Survey. In permanent, randomly placed plots it records:

1. the richness and abundance of every vascular plant species, native and non-native;
2. basal area, density and health of all woody species;
3. the density of fuels on the forest floor;
4. disturbances across the community, including insect pests and disease;
5. physical conditions such as landform shape, soil nutrients, and canopy cover and height.

Sampling concentrates on the habitat types covering more than 30% of a park, and extends to less common ones when time and money allow.

Vegetation plots set up in summer 2021 at Chattahoochee River National Recreation Area. NPS.

The park

Chattahoochee River National Recreation Area follows 77 km (48 mi) of the Chattahoochee River north of Atlanta, Georgia. One of the largest urban parks in the country, it makes up about 20% of metro Atlanta's green space. Here the river follows the Brevard Fault Zone, which separates the Outer and Inner Piedmont in Georgia and Alabama. Former land use and local soil conditions largely decide where its forests grow: pine, oak and mixed hardwood forests at early to middle stages of succession on the uplands, and flood-tolerant hardwoods on the wet bottomlands.

The protocol was used here for the first time in 2021, establishing 30 plots in Piedmont Alluvial Wetlands and Piedmont Upland Forests as a baseline.

A landscape shaped by people

Since European settlement, the land has been cleared for farming and timber, and over the past century urban development has added pressure. Urbanization likely helps invasive species spread and discourages the use of fire to restore natural processes. A century of fire exclusion has degraded oak-hickory forests across Georgia's Piedmont; the park's drier ridgetops and gentle slopes surely once supported fire-adapted ecosystems, and without fire or a substitute they are likely to fill in with moisture-loving, fire-intolerant hardwoods.

What the survey found

• 299 plant species across all plots, including 29 not found in earlier surveys, and one rare species tracked by the Georgia Department of Natural Resources — large-fruited sanicle (Sanicula trifoliata).
• Plot richness ranged from 16 to 75 species, with trees and herbs contributing most of the diversity in both habitats.

Average species richness of different plant growth forms by habitat. NPS.

• Non-native plants were common in every plot and habitat. Sixteen species classed as invasive by the Georgia Exotic Pest Plant Council turned up. Chinese privet (Ligustrum sinense) dominated the seedlings and saplings of the wetland plots; Japanese honeysuckle (Lonicera japonica), Japanese stiltgrass (Microstegium vimineum) and Chinese holly (Ilex cornuta) were also frequent.

Average share of native and non-native species by habitat. NPS.

• Green ash (Fraxinus pennsylvanica) trees in the wetlands were dying at a high rate, most likely because of the invasive emerald ash borer (Agrilus planipennis).
• Dominant trees: in the wetland plots, tuliptree (Liriodendron tulipifera var. tulipifera), loblolly pine (Pinus taeda), boxelder (Acer negundo var. negundo) and river birch (Betula nigra); in the upland forests, white oak (Quercus alba), loblolly pine, tuliptree and mockernut hickory (Carya tomentosa).

The plots were scheduled to be resampled in summer 2024.

About the network

The Park Service began its Vital Signs Monitoring program in 1999 so that more than 270 parks could track their highest-priority measures of resource condition. Its goals are to determine the status and trends of park ecosystems, give early warning of abnormal conditions, improve understanding of how ecosystems change, meet legal and congressional mandates, and measure progress toward performance goals.

The Southeast Coast Network covers eighteen administrative areas with twenty park units, fifteen of them with significant natural resources — four national seashores, two national historic sites, two national memorials, six national monuments, two national military parks, a national recreation area, a national battlefield, a national historical park and an ecological and historic preserve — across North Carolina, South Carolina, Georgia, Alabama and Florida. The parks range from just over 20 to nearly 60,000 acres and together cover more than 184,000 acres of federal land, or more than 253,000 acres counting non-federal land managed jointly with the Park Service.

Sources

• National Park Service, Southeast Coast Network: "Terrestrial Vegetation Monitoring 2021 Data Summary for Chattahoochee River NRA," with the full report in the NPS DataStore. Run-together and misspelled species names in the summary ("Pinustaeda," "Betulanigra," "lobolly") are corrected.