Palustris Experimental Forest

A mature longleaf pine stand

A mature longleaf pine stand

Congress designated the Palustris Experimental Forest in 1935 as an area for conducting forestry research. The Forest is named in recognition of the species longleaf pine (Pinus palustris) that, prior to the widespread harvest of virgin pine forests in the early 1900’s, once occupied over 89 million acres (36 million ha) in the American South. The Experimental Forest includes two separate tracts of public land within the Kisatchie National Forest that total about 7500 acres (3035 ha). The Southern Research Station supervises and conducts a wide range of long-term and other studies on these unique and scientifically valuable lands.

The Palustris was established due to the efforts of pioneer researcher Philip C. Wakeley with the goal of developing reforestation techniques for the four major southern pines. With the help of the Civilian Conservation Corps, Wakeley and other scientists grew seedlings at the Stuart Nursery near Pollock and outplanted them on the Palustris to develop nursery technology and stock specifications for planting of southern pines. Almost ¾ million southern pine seedlings were outplanted during the mid- to late-1930s and were critical to the understanding of how to successfully reforest the denuded landscape.

A controlled burn in a longleaf pine stand

A controlled burn in a longleaf pine stand

Early research on the Palustris included cone and seed studies that would become the basis for reforestation success throughout the South and around the world. Direct-seeding operations showcased a means by which denuded landscapes could be quickly reforested; and new seedling production techniques developed here pioneered the current capability of tree nurseries to produce over a billion seedlings per year. Woody plant-control methods developed on the Palustris demonstrated how unproductive sites could be converted to thriving pine forests; and how established forest stands could be intensively managed to enhance their economic productivity.

Climate

Annual precipitation averages 58 inches (1465 mm) with fairly even monthly distribution. During the winter and spring, the average rainfall is 30 inches (754 mm) compared to 28 inches (711 mm) in the summer and fall. October is usually the driest month. Temperatures average 72°F ( 22 °C) with minimums of 23°F (-5°C) and maximums of 95°F (35°C).

Databases

Monthly rainfall and temperature data have been collected since 1950. Hourly maximum/minimum air temperatures, soil temperature, solar radiation, wind speed, and precipitation have been collected using automated weather stations since 1986.

Numerous long-term (30 to 65 years) growth data sets have been collected for longleaf, loblolly, and slash pine. These data are the basis of growth and yield prediction systems that have been developed for these species. Other studies quantifying intensive soil and tree physiology measurements have been underway for about 10 years.

Location and examples of research

The J.K. Johnson Tract (92° 41’W, 31° 10’N), located 18 miles (29 km) southwest of Alexandria, Louisiana, on highway LA-488, is named in honor of one of the first industrial foresters to reforest southern pines. This 2500 acre (1012 hectare) site is home to long-term studies such as a longleaf pine spacing, prescribed burning, pruning, and thinning regime study that is now about 65 years old. Some areas of the Johnson Tract are used for shorter-term studies that allow scientists to evaluate seedling physiology. In addition, innovative research is now underway to evaluate the effects of global climate change on forest productivity and to devise management strategies to reduce such effects. Using very intensive measurements of tree and stand morphology and physiology, studies like this involve ongoing, cooperative efforts with a full range of partners. Research conducted on the Johnson Tract is now benefiting from some of the most sophisticated equipment available to plant scientists.

The Longleaf Tract (92° 36’W, 32° 0’N), about 35 miles (56 km) south of Alexandria, Louisiana, off highway US-165 near Glenmora, was added to the Palustris in the late 1940’s. It has been the site of some of the most intensive multi-resource research in the South. Since the 1940’s, the interactions of cattle grazing, wildlife management and timber production have been evaluated. This research was critical to reforestation efforts following World War II. During the War, the vast cutover longleaf pine forests became grasslands where herds of cattle and hogs roamed freely. Successful reforestation efforts required that the interactions among cattle, hogs, and trees be understood. This effort has provided the information necessary to allow integration of grazing, wildlife habitat, and forest productivity. Current research emphases include evaluations of effects of forest management practices on long-term soil productivity. With burgeoning human demands for forest products and amenities, scientists are using the Longleaf Tract to evaluate the effects of timber harvesting, prescribed fire, site preparation, and pine straw utilization on soil structure, nutrition, and chemistry; the ecology of soil microorganisms; soil-plant moisture relationships; and plant productivity.

Collaborators and opportunities

The Palustris is a field research laboratory, a demonstration site for new forestry practices and, above all, an area where a broad cross section of the scientific community can work together to help make effective and efficient use of American’s forest resources.

Facilities

In addition to the forest itself, the Johnson Tract has facilities that include offices, laboratories, warehouses, shops, and equipment sheds.

For more information, call Research Unit Headquarters, Auburn, AL 334-826-8700.