Longleaf Pine on the Santee Experimental Forest

Restoration and Shared Stewardship

Mature longleaf pine forests provide shelter and food sources for red-cockaded woodpeckers. Nest cavity trees on the Santee Experimental Forest will be preserved, along with buffers of forage habitat. Photo by Julie Arnold, USFS.

In 1989, South Carolina’s Francis Marion National Forest lost close to a third of its pine and hardwood trees to Hurricane Hugo. USDA Forest Service land managers have spent the last thirty years recovering from that disturbance and working to meet the state’s growing needs for clean water, forest products, recreation areas, and wildlife habitat.

To that end, the Francis Marion adopted a new forest plan in 2017 focused upon restoring longleaf pine, the once-dominant southern species, across 33,000 acres of national forest lands.

This goal and the management work to implement it are based on a body of experimental research about forest ecology and hydrology — much of it conducted on the Santee Experimental Forest.

The Santee sits on the west side of the Francis Marion. Established in 1937, it’s a 6,100-acre living laboratory that has hosted many long-term studies on the effects of fire, hurricanes, and forest management practices on tree growth, streamflow, and wildlife communities.

SRS scientists and national forest managers have teamed up to study the impacts of replacing existing loblolly pine stands with longleaf pine.

Earlier, fine-scale studies suggest that water yield from longleaf pine landscapes may be greater than that from loblolly pine or mixed pine and hardwood stands due to differences in forest structure and composition between the two pine environments.

“Longleaf pine restoration is a priority for the Southern Region of the National Forest System,” says research soil scientist Carl Trettin. “This project is an opportunity to advance the current science on longleaf restoration to broader scales as well as support the Region and the Forest.”

Forestry technician Julie Arnold downloads and manually measures soil moisture data at a well. Scientists will develop models from these and other field datasets to simulate future longleaf pine forest conditions. Photo by Andy Harrison, USFS.

Compared to loblolly stands, longleaf pine forests are less dense, with fewer large trees in the canopy and a more open understory dominated by grasses and sedges.

In a longleaf pine stand, less rainwater is lost through evaporation, allowing more rainwater to seep through the soil to the groundwater. “In addition, the two trees allocate above- and belowground carbon differently,” adds Trettin.

The current study features three treatments in one watershed of Huger Creek, known as WS-77, as well as an untreated watershed in the same headwaters area, WS-80.

In the first treatment, 140 acres of loblolly pine will be harvested then replanted with longleaf pine seedlings.

The second treatment involves thinning 160 acres that currently include longleaf pine. This treatment will retain critical habitat for the red-cockaded woodpecker and encourage natural longleaf regrowth.

The third treatment, 50 acres, combines thinning and creating small openings that will be replanted.

A National Environmental Policy Act, or NEPA, review was completed for the project in 2018. Since then, scientists have been collecting baseline tree, soil, and water measurements.

The treatments will begin in 2019 through a Good Neighbor Authority (GNA) agreement with the South Carolina Forestry Commission. This agreement will expedite the timber harvest, helping to improve the health of the forest and contributing to the local economy. This is the first Experimental Forest in the South to conduct a sale using the GNA.

“The broad agreement is in place, and now we’re working on a supplemental agreement with specifics pertaining to the WS-77 timber sale,” says Russell Hubright, SCFC forest management chief. “We’ve had successful state-federal projects in the past and look forward to this partnership with the Forest Service.”

A year after the harvest, the team will conduct prescribed burns to reduce logging residue and wildfire fuel loads. Longleaf pine planting will take place two years after the harvest and be monitored seasonally and annually. Scientists will develop models from the data collected to simulate future longleaf pine forest conditions.

Hydrology technician Andy Harrison measures water yield as part of a long-term seasonal and annual monitoring effort on the Santee Experimental Forest. Photo by Julie Arnold, USFS.

These model projections can be combined with long-term monitoring data to track the progress of the restoration, anticipate potential changes or risks, and adjust management decisions to keep the desired outcomes on target.

Researchers can also use the models to link the Santee project to other restoration efforts in the region – not just in wet pine flatwoods, but anywhere in the South where forest management plans might be informed by landscape-scale forecasts.

SRS manages a network of 19 Experimental Forests, including the Santee. For decades, scientists have investigated research questions that are as diverse as the Experimental Forests themselves. Recent efforts to link these sites as a functional network will facilitate new research questions and collaborations and increase efficiencies.

The Santee project demonstrates how the SRS network can bring together expertise and tools to answer important questions about the sustainability of Southern species and their environments. The SRS network plans to replicate similar measurements at a second coastal plain forest based on the Santee model.

In addition, Forest Service staff from this project are working with Clemson University, College of Charleston, and partner organizations like The Longleaf Alliance and NRCS South Carolina to reach local landowners and share technical assistance about restoring, improving, and maintaining longleaf pine forests on private lands.

The project is an example of strategic, science-based management conducted in the spirit of Shared Stewardship to meet the shared goals of the national forest and its partners.

Learn more about the network of Experimental Forests across the Southern Research Station.

For more information, email Carl Trettin at carl.c.trettin@usda.gov.

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