Summer 2005

What Can Experimental Forests Teach Us About Longleaf Pine Restoration?

Since the 1920s, the USDA Forest Service has maintained a system of experimental forests to test hypotheses and collect longterm data about the ecological effects of fi re, grazing, insect infestations, air pollution, and other disturbances. In the South, researchers from Federal agencies and universities use 15 active experimental forests for studies ranging from the practices needed to maintain healthy forests, to the water filtration functions of forests, to habitat restoration for endangered species.

Experimental forests are some of the few places in the United States where longterm data are collected about forests and how they change over time. These living laboratories also serve as demonstration sites where cooperators and landowners can see the results of different forest management options.

In 1935, the USDA Forest Service established the 7,500-acre Palustris Experimental Forest as a research study plot on the Kisatchie National Forest. The Palustris was representative of the surrounding territory in central and southwestern Louisiana and east Texas: it had once supported magnificent longleaf pine stands, many of which were destroyed by railroad and cable logging in the early part of the century. Later attempts to farm on the shallow, poorly drained soil had failed, and many of the longleaf stands were left barren or invaded by scrub oaks and other undesirable hardwoods.

Early research on the Palustris concentrated on fi nding methods to reforest the cutover land, first by introducing loblolly and slash pines and later by reestablishing the more disease-, fire-, and storm-resistant longleaf pines. On stands that lacked the remnants of a longleaf ecosystem to shelter and nurture young trees, researchers transplanted nursery-grown bare-root seedlings and then tested different treatment combinations to help them survive until their roots could recover.

Although somewhat effective, planting bare-root seedlings proved to be more labor intensive and expensive than was practical for landowners with large acreages of cutover land, so new experiments began on direct seeding. This research resulted in guidelines for site and seedbed preparation, ideal timing for sowing, quantity and quality standards for seeds, and methods to protect against losses to birds and grazing animals.

As the stands in the experimental forest grew from the seedling to sapling stage, researchers tested longleaf growth responses to thinning and pruning, and the effectiveness of prescribed burning in reducing competition from faster growing trees. Responding to landowner needs for income production on the slow-growing longleaf acreage, they introduced grazing on some plots and measured both the seasonal weight gains of the cattle and the ecological effects on the trees.

Today, visitors to the Palustris can see 80-year-old longleaf pine stands that demonstrate the long-term effects of various treatments and planting methods, including the newest study results on container-grown seedlings. Ecophysiology studies are underway with Louisiana State University faculty to understand relationships between tree physiology and belowground processes. These studies will provide tools that will help landowners manage their longleaf stands to mitigate the effects of global change.

Again, responding to landowner needs and recognizing that pine straw has more potential for income than timber, researchers have begun testing the effects of alternative pine straw harvesting methods on soil and stand productivity. Their goal is to develop guidelines for maximizing income while maintaining productive and healthy longleaf stands.

Across the South, private landowners are expressing renewed appetite for the aesthetic and wood-quality values of the more diffi cult to establish longleaf pines. They will fi nd that the Palustris Experimental Forest is an excellent repository of practical information, and that it serves as a living reminder that longleaf restoration is both possible and worth the effort

Palustris Experimental Forest

http://www.srs.fs.usda.gov/longleaf/

For more information:

James Haywood at 318-473-7226 or
dhaywood@fs.fed.us

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