Cross-Site Studies Take Root across the Southern Experimental Forest Network

a pine stand
Tree breeding research on the Olustee Experimental Forest laid the foundation for the establishment of seed orchards throughout the South. Photo by Don Bragg, USDA Forest Service.

Most of the 19 southern experimental forests were founded in the 1930s or 1940s. Over the past five years, they have become something new: the SRS Experimental Forest Network.

“Each experimental forest is a regional asset,” says Stephanie Laseter, a USDA Forest Service scientist and network co-lead. Johnny Boggs is also a co-lead.

“When part of a network, each forest becomes more valuable,” says Boggs. “The Experimental Forest Network allows ideas, people, data, and resources to flow across each forest.”

A recent analysis by Ge Sun and Erika Mack compared precipitation, water yield, and evapotranspiration across sites on all experimental forests in the Network. The work is a foundational step towards understanding the sites that make up the network and will make studies that span multiple experimental forests even more useful. Rabio Olatinwo and JT Vogt have also completed analyses on drought indices across the Network. Several cross-site studies are already underway, and some are nearing completion. Chuck Burdine serves as western regional coordinator and Bryan Mudder is the eastern regional coordinator.

Experimental forests have changed the southern landscape – and for the better. For example, ways to re-plant and grow southern pines were developed on the Palustris Experimental Forest (EF) and others. Re-planting was critical in the early 1900s, as millions of acres of ancient longleaf pine forests in the western Gulf Coast Plain had been clearcut. Research on longleaf pine, shortleaf pine, and other southern pines continues on the Crossett, Escambia, Santee, and Palustris EFs.

a person collects water samples from a weir
Boggs collects a water sample from a flume at the Hill Demonstration Forest. He helped manage these paired watersheds for 12 years and conducts research there. Photo by Johnny Boggs, USDA Forest Service.

Today, research often focuses on an entire landscape or region. “We need a common set of measurements across all experimental forests,” says Boggs. “We want to develop and answer broader landscape research questions.”

Support from the Forest Inventory and Analysis Program of the Forest Service will make this possible. FIA is the nation’s forest census, collecting data on soils, microbes, land ownership, carbon, invasive plants, and of course, trees.

“FIA plots and collection methods are a low-cost, reliable way to generate a consistent set of measurements across the Network,” says Bill Burkman, SRS FIA program manager. FIA has well-documented protocols for plot installation, monitoring, and data management.

All 17 of the permanent FIA plots have been established on the Palustris EF. Plots are sampled as they are installed, so the plant communities and other metrics of these plots have already been documented according to FIA protocols.

The crews are now installing plots and sampling on the Bent Creek EF. A few experimental forests, such as Coweeta, Calhoun, and Santee, already have some intensified FIA plots, but most do not. Originally, Boggs and Laseter planned for all plots to be installed by 2024. These plans were disrupted due to the pandemic, but field crews are still making progress.

The Experimental Forest Network has broad support. The Southern Region of the National Forest System shows support in many ways: Most experimental forests are on National Forest System lands, and districts have always helped repair roads, survey vegetation, conduct prescribed fires, and more.

four people at the Blue Valley Experimental Forest
Laseter (second from left) organized tours of the Network’s eastern and western experimental forests. Photo by Richard McClure, USDA Forest Service.

University partners include Duke University, Florida Agricultural and Mechanical University, Mississippi State University, North Carolina State University, Oregon State University, Stephen F. Austin State University, Tuskegee University, the University of Georgia, and the University of Kentucky.

Each experimental forest has different levels of staffing, data, and active research. Many sites have decades of data, although not all of it is in digital form or accessible.

At Coweeta Hydrologic Laboratory, 80 years of temperature and precipitation data, combined with data from four newer weather stations, show that temperatures have been warming since the late 1970s, while droughts have become more frequent and severe. Other long-term datasets from Coweeta have provided crucial insights on sustainable harvesting methods, soil nutrient cycles, and the links between forest management and water.

Read part one of this story.

Read more on the Experimental Forest Network website.

To conduct research across the SRS Experimental Forest Network or access historic data, contact Johnny Boggs (johnny.boggs@usda.gov) or Stephanie Laseter (stephanie.laseter@usda.gov).

Access the latest publications by SRS scientists.

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