Longleaf pine ecosystems may be the key to creating more drought-resilient forests, according to a study that Lisa Samuelson, Alabama Agricultural Experiment Station researcher and Alumni Professor in Auburn’s School of Forestry and Wildlife Sciences, is conducting.
“Due to the challenges related to climate and water availability, a better understanding of ecosystem behavior is needed to improve the management and conservation of our forests,” Samuelson said. “The goal of this study is to gain a better understanding of longleaf pines’ role in creating resilient forests for the future.”
Longleaf pine once was one of the most extensive forest ecosystems in North America, covering an estimated 90 million acres. Today, due to overharvesting or forestland conversion to farming or development purposes, less than 4 percent of longleaf pine forests remain.
Samuelson, who is also director of Auburn’s Center for Longleaf Pine Ecosystems, an entity dedicated to the species’ restoration, conservation and management, said the reduction in the amount of longleaf communities has incurred many ecological consequences including loss of plant and wildlife species. Besides preserving these species’ habitats, rejuvenation of the once-abundant pine also may improve overall forest health due to its ability to withstand drought.
“There is increased interest in the restoration of longleaf pine forests, not only for forest products but for a variety of important ecosystem services and, more recently, as a species resistant to disturbances associated with changes in climate,” Samuelson said. “Our research will provide information on the current and future vulnerability of longleaf pine to drought.”
The study site is an 11-year-old longleaf pine plantation owned by the Georgia Department of Natural Resources and managed by The Nature Conservancy. Samuelson’s objective is to explore the longleaf pine’s drought adaption patterns and its resilience in relation to its ecosystem. Basically, she and her research team are manipulating drought to study its effects.
“Our study is unique in that we are removing precipitation to study drought effects,” she said. “Whereas most studies utilize irrigation to remove drought effects, we are creating drought.”
To remove about 40 percent of the water that typically would hydrate ground in the experimental plots, the researchers have installed rainfall exclusion troughs that catch precipitation and transport it away from the trees’ roots.
Keeping detailed records of soil moisture dynamics, the scientists then use extensive monitoring equipment, including sap-flow probes and 30-foot-tall scaffolding, to examine above- and below-ground mechanisms that control tree growth and survival. The team monitors total tree health in the absence of hydration, including stand transpiration, leaf physiology, soil and ecosystem carbon fluxes, needle and shoot phenology, photosynthesis and phenology.
Once collected, the soil moisture data will be used to create predictability scales for regional and seasonal drought patterns, and the tree-growth/health data will contribute to the development of parameters and models that simulate longleaf pine growth under varying climate and fire regimes.
Ultimately, the research data will benefit the overall effort to improve the management of Southern forests, Samuelson said.