Climate Impacts at Congaree

A visitor explores the floodplain forest at Congaree

NPS photo

Congaree National Park draws well over a hundred thousand visitors every year. As of 2009, Congaree had over 20 documented state and national champion trees, or trees that have been judged to be the largest of their species. Some of our champions are hundreds of years old! As of 2015, the park is working with partners to catalog new champions.

The Congaree floodplain forest is a testament to a time when South Carolina was lush and wild. This ecosystem is one of the last and best-preserved swaths of this historic landscape. It connects us with our past and has been preserved for our future.

Climate change is already impacting park resources. Our best chance in the fight to protect Congaree is to mitigate our carbon footprint, adapt to the changes we are already experiencing, and prepare for future impacts by working to keep the forest and watershed as healthy as possible.

Hydrology

The moisture and nutrients provided by the flooding of the Congaree River define and sustain this ecosystem. Since the river is the lifeblood of the floodplain, we can expect the area to change with the water.

Congaree National Park is located downstream of Columbia, the capitol of South Carolina. The frequency, magnitude, timing, and duration of flooding and the quality of the river water influence the forest community and the geomorphology of the park.

The regional seasonality of rain is shifting in this watershed. More rain is coming in short downbursts which can increase flash flooding. As floods and droughts increase, the forest ecosystem will be impacted. Increased development in Columbia and beyond will also have an effect on Congaree's natural systems.

A family of feral hogs rooting in the ground

NPS photo

Invasive Species

Invasive species are one of the most serious problems facing Congaree. Many invasive species are aggressively competing with native species for resources. Increased temperatures in the north allow exotic plants and animals to move up from the south, thereby largely expanding their distribution.

Feral hogs are one of the most damaging invasive animals in the park. They are intelligent, highly adaptive, and destructive. They reproduce quickly, have few natural predators, and carry pseudo rabies and brucellosis, diseases that can be passed to domestic animals and humans. Hogs voraciously eat native plants and wildlife, thus decreasing the diversity of plants and animals in the park. They also root and wallow, causing erosion and aiding the growth of invasive plant species. The damage they cause can have long-term impacts on the entire ecosystem.

Japanese stilt grass (Microstegium vimineum) is an invasive plant species spreading across the Southeast region. The grass has a weak root system that is not strong enough to prevent soil from eroding. The grass is tall, however, and shades out native, strong-rooted plants that are better at controlling erosion. It greatly contributes to soil degradation and poses a risk to watersheds and ecosystems.

These are only two examples of invasive species at Congaree. The threat of invasive animals and plants will only grow as temperatures continue to increase, allowing them to reach north and inland and extending their growing and reproductive seasons.

Yellow jessamine, South Carolina's state flower, blooming in the Spring

DPR North Carolina

Phenology

Phenology is the study of the timing of annual events, including leafing, mating, migration, flowering, and more. Many of these events are triggered by environmental cues such as temperature. Plants, animals, and insects are reacting to temperature rise and longer warm periods. Important actions, such as pollination, depend on synchronized life cycles of plants and animals. If changes are not synchronized, long-established relationships may be broken, resulting in an extreme disruption of the ecosystem.

In South Carolina, changes in amphibian life cycles have already been documented. Autumn breeders are starting later while winter breeders are starting earlier. At a similar floodplain close to Congaree, amphibians are breeding up to 76 days earlier than before! This completely changes predator-prey relationships and resource competition in the ecosystem.

Poison ivy and vines present another example of changed relationships in our forest. Poison ivy is stronger and spreads faster with increases in carbon dioxide in the air. Other vines are increasing in range and density, weighing down smaller trees. We expect many other plant and animal species are changing their behaviors as the climate changes. This will derail the natural order of the forest and change some species' ability to meet their survival and reproductive needs.

Research at the park continues: studies like citizen-science bird counts and butterfly counts help inform our adaptation and management strategies at Congaree.