The Longleaf Pine
Among the Southern pines, longleaf pine (Pinus palustris) has several key characteristics that have allowed it to grow on some of the harshest sites in the southeastern United States. One is its fire tolerance. Fire is a critical component of the longleaf pine ecosystem, and longleaf evolved with understory species, like the bunchgrasses, which help spread a fire. The longleaf pine needles are very flammable, providing additional fuel on the forest floor. Longleaf pine is also pruned by fire, which raises the crown of the trees above surface fuels more quickly than other pine species. Finally, longleaf bark thickens as the tree ages, with mature trees having distinctive bark plates.
Another of its most well-known survival strategies is the time a young longleaf spends in the grass stage of development. Following germination and establishment, the growth of young trees is focused on establishing a deep taproot, with their above-ground portion looking like clumps of grass. This increases survival chances on the deep, droughty soils where longleaf often grows since the tree will have a sufficient root system established to support itself before it initiates height growth. During this stage, which can last from one year to several years, the trees are also very resistant to fire since a thick tuft of needles surrounds the terminal bud.
Height growth is initiated once the young trees have developed sufficient taproots, which can be over 10 feet long. This is called the “rocket” stage since the stems will begin rapid elongation, often growing several feet in a growing season. Stems in this growth stage look like a bottlebrush, lacking lower limbs. This is the growth stage when the longleaf is most susceptible to damage from a fire until bark thickness increases and the terminal bud is safely above typical ground fire height. As longleaf pines grow through their sapling stage and into merchantable stands, another survival strategy is their ability to avoid stagnation and respond to thinning with increased growth even at 100 years of age. Longleaf can reach over 100 feet on good quality sites and live 300 years or longer. Its long needles, which can reach over 15 inches, are where its name is derived from.
The density of longleaf pine wood, its resistance to rot, and its straight growth form make it a desirable species for many solid wood products. Additional income can be generated by producing pine straw, and leasing managed longleaf stands for hunting and other recreational activities. Longleaf is naturally more resistant to insects and diseases than the other southern pine species. It can survive and grow on the deepest sand sites where loblolly and slash pine would be severely stunted.
The History of Longleaf Pine
The historic range of the longleaf pine ecosystem was 92 million acres and stretched from southeast Virginia to east Texas. Fire has been well documented as the factor that shaped and maintained the longleaf pine ecosystem for thousands of years. Natural fires started by lightning strikes, which occurred most often during the growing season, shaped communities of vegetation dominated by fire-tolerant and fire-dependent species. Stopped only by rainfall or water bodies such as creeks and rivers, these fires burned the landscape in a mosaic pattern, with a frequent return interval. Native Americans adopted fire as their primary tool to continue manipulating the ecosystem, using it to improve wildlife habitat and create more palatable forages, drive game during hunts, make travel easier, and increase their ability to protect themselves from attack by warring tribes. The most significant change that came to the landscape through Native American use of fire was the human-set dormant season fires, which created an even greater mosaic of vegetation stages across the longleaf range.
Early explorers documented the park-like conditions of the open longleaf stands they traveled through and their unique flora and fauna. In William Bartram’s exploration of the southeast in the 1770s, he described “a vast forest of the most stately pine trees that can be imagined,” stretching as far as he could see over many miles. While Native American populations drastically declined in the 1600s due to diseases brought to the United States by Europeans, early settlers quickly adopted a similar burning regime to maintain grazing for their livestock and improve hunting conditions. However, their use of tools to clear land for agriculture and settlements created one of the earliest declines in the distribution of longleaf pine stands across the landscape.
The introduction of cotton across the southeast as a cash crop led to even more rapid clearing of longleaf forests for agricultural production. As settlements grew, so did the use of the longleaf forest to produce commodities such as naval stores and other forest products such as lumber and poles. By the mid-1800s, the development of steam-powered locomotives resulted in a faster method of moving forest products to market. Southern pine timber demand continued to increase as northern forest stands were clearcut, and World War I caused a spike in the need for naval stores and lumber. These factors resulted in the beginning of the end for vast acreages of virgin longleaf pine forests by the Great Depression.
The “second forest” of longleaf that followed decades of exploitation was a fraction of the native range and often contained low-quality, widely scattered stems. Longleaf pine’s large, heavy seed rarely falls more than 65′ from the parent tree, and the large-scale harvesting of the virgin stands often left no seedtrees on site. Even with seedtrees on site, irregular bumper seed crops of only every 5 to 7 years allowed competition to develop in the absence of fire, reducing the ability of the seed to contact mineral soil and germinate. Also, the feral hogs introduced by European settlers devastated small longleaf seedlings. The most successful stands of the second forest were found on sites where adequate advanced regeneration was in place when the virgin forest was harvested and where fire continued to be used by landowners. A growing challenge to using fire as a management tool began in the early 1900s as fire began to be viewed as a threat in any forested ecosystem, particularly by land managers from the north and west unfamiliar with the benefits of prescribed burning. The impact of Smokey Bear’s message of “Only You Can Prevent Forest Fires” supported the new fire exclusion policies being made by state and federal agencies.
Beginning in the 1930s, a shift to planting loblolly and slash pine began across the southeast to feed the new pulp and paper mills built after the discovery that paper could be manufactured from southern yellow pine. State and federal tree planting efforts, including the Soil Bank Program of the 1950s, further increased the number of acres being converted from longleaf pine to other species. With fire removed from the landscape, the conversion of former longleaf stands to plantation pine, and the further growth of the southeast’s population, longleaf pine acreage continued to shrink. By 2000, the ecosystem was at a record low of 3.2 million acres, a loss of 97% across its historic range.
Restoration Efforts in the Longleaf Ecosystem
The loss of the historic range of longleaf pine has led to the decline of North America’s most diverse plant communities. Over 900 plant species have been documented as only occurring in the longleaf ecosystem, with up to 170 species found on a quarter-acre plot. Longleaf stands provide habitat for over 100 bird species, 170 reptiles and amphibians, and over 30 mammals, with 30 species classified as rare, threatened, or endangered (RTE) by the US Fish and Wildlife Service.
Planting of longleaf pine within its native range is a significant focus in the ecosystem’s restoration. These efforts have increased the range to a current area of 5.2 million acres, with a goal of 8 million acres by 2040. Millions of dollars from public and private sources have been spent establishing longleaf stands on state, federal, and private lands. Another critical component of restoration efforts is reintroducing prescribed fire in longleaf stands, particularly on private lands. Funding sources for this practice have also been available, but the lack of capacity of qualified burners is still a challenge to meeting annual prescribed fire goals.
Plant restoration efforts focus on increasing native groundcover species, especially those that provide food and cover for ecosystem fauna, as well as those that help carry fire through the understory. These efforts have multi-pronged approaches, including eliminating invasive species, controlling understory and midstory woody stems that become established in the absence of fire, and reseeding with desired species.
Restoration efforts also focus on keystone animal species across the longleaf pine range. The red-cockaded woodpecker, the only woodpecker to build cavities in live trees, was listed as endangered in 1970 due to habitat loss of the mature, fire-maintained pine stands it needs for cavity construction and foraging. Population estimates have been as low as 10,000 birds, or about 1% of the birds’ pre-European settlement numbers. In efforts to reduce the rate of the decline, management has focused on installing artificial cavities, translocating birds to suitable habitats, and increasing the acreage burned in mature pine stands to control midstory vegetation.
In South Carolina, a joint project with several state and federal agencies and conservation groups focusing on the gopher tortoise is an example of efforts to reverse the impacts of longleaf pine habitat loss. The gopher tortoise can live up to 50 years old and is unique in that it digs underground burrows that can reach 15 feet long. These burrows provide homes for hundreds of other species and are a refuge when a fire burns across the landscape. The gopher tortoise feeds on the vegetation in the understory surrounding its burrows, most of which are fire-dependent plant species. The gopher tortoise’s native habitat has been impacted by decades of parcelization and fragmentation, reduction in burning, increases in invasive species and climate change. Conservation efforts are being developed to reverse these impacts before the gopher tortoise populations decline further in the state.
Lisa Lord, Conservation Programs Director with The Longleaf Alliance, recently provided an update on their project. “Increasing and sustaining gopher tortoise populations often requires multiple strategies — from restoring and maintaining longleaf habitat with prescribed fire to improving juvenile survival in the wild. Since 2016, The Longleaf Alliance, UGA Savannah River Ecology Lab and SC Department of Natural Resources have partnered to augment and restore gopher tortoise populations through a technique called “head-starting.” About 350 eggs have been collected from wild populations to hatch in captivity and released at two properties in South Carolina. Hatchling tortoises are reared indoors at the Savannah River Ecology Lab for one year to achieve larger body sizes than would occur naturally and thus become more resistant to predation. This practice gives tortoises a greater chance to survive and eventually grow into adulthood”.
If you are interested in establishing or managing longleaf pine on your property, please contact your local Clemson Extension FNR team member. Additional resources on longleaf pine management and funding can be found on The Longleaf Alliance website at https://longleafalliance.org/ and on the USDA Natural Resources Conservation Services Longleaf Pine Initiative website at https://www.nrcs.usda.gov/programs-initiatives/longleaf-pine-initiative.
Author
Janet Steele, Cooperative Extension, Forestry and Wildlife Agent
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