The demise of tropical rainforests is often identified because of the impact on biodiversity. Conservationists point to the remarkable number of species occurring in these low latitude ecosystems when they are well maintained. Conversion of these natural areas to alternative uses comes at a cost of habitat loss supporting the enormous range of organisms.
An ecosystem of nearly equivalent biodiversity occurs in our own backyard! Longleaf pine savanna once covered more than 90 million acres in what is now the Southeastern U.S. That is nearly 2-and-a-half times the size of Georgia. Preceding European settlement, longleaf covered an area from eastern Texas, through the panhandle of Florida extending through the coastal plain region of the Carolinas and into southern Virginia. William Bartram, a colonial explorer and naturalist, described the landscape in 1791 as a “forest of the great long-leaved pine, the earth covered with grass, interspersed with an infinite variety of herbaceous plants, and embellished with extensive savannas, always green, sparkling with ponds of water.”
More than 1,200 endemic plant species and in excess of 300 rare or threatened animal species have been cataloged in longleaf savannas. Both the red-cockaded woodpecker and the gopher tortoise depend on the habitat unique to the longleaf pine ecosystem for their survival. Plant diversity creates and abundance of distinct and unique microhabitats that contribute to corresponding animal diversity.
A distinct characteristic on the longleaf pine and the associated plant community is a dependence on frequent, low-intensity fire. Ecologists refer to this as a “fire obligate” system. Although sometimes called a forest, the longleaf pine ecosystem is more properly designated as a savanna. Like those in Africa, North American savannas may be described as grasslands rather than forests. In a mature longleaf stand, trees are widely spaced and the understory of grasses and forbs receives large quantities of direct sunlight, unlike the heavily shaded understory of a forest. This herbaceous understory provides the fuel for frequent fire, but these plants are well adapted and recover quickly.
Adaptation of the longleaf pine itself is amazing. Seeds must be in contact with bare soil, a consequence of prior fire, in order to germinate. Young seedlings are described as having a “grass stage.” In case of fire, long needles serve to protect the terminal bud, which remains close to the soil surface. For several years the seedling invests growth below ground, storing reserves. When adequate reserves are available, the tree grows very rapidly, reaching several feet in a single growing season. This “growth spurt” elevates the growing point higher than flames from a low intensity fire and permitting continued growth. This adaptation, along with frequent fire, provides a substantial competitive advantage over other trees, both evergreens and hardwoods.
Longleaf pine drop lower branches when exposed to flame, creating a smooth, straight trunk. Slow growth, leads to narrow growth rings and dense timber making them ideal for ship masts, railroads, telephones poles, construction lumber, flooring and furniture. Aggressive harvest, land use conversion and fire exclusion have led to a drastic decline in longleaf pine, particularly old growth stands. Current estimates suggest that longleaf pine now covers 4.5 million acres in the South, 5% or so of the pre-Colonial extent. Most of the current longleaf acreage, roughly 73%, is owned privately. Proper management of existing or newly established stands will depend on private landowners embracing frequent use of prescribed fire and access to capable advisors to plan and conduct prescribed burns. Without fire, stands will suffer the establishment of hardwoods which will compete for resources and convert the fuel load to damaging levels should a fire occur.
Most longleaf pine occurs on the sandy, light-textured region of the coastal plain. Botanists have identified a distinct longleaf which occurs in areas further inland, such as the ridge and valley region of northwest Georgia. Students and scientists at Berry College recognized an old growth stand of mountain or montane longleaf pine (Pinus palustris). When first evaluated in about 1995, the stand had been degraded by decades of fire suppression. A management plan has since been designed and implemented and a number of studies have helped identify useful tools including prescribed fire, herbicide and re-planting, to continue improvement of the tree stand and the many associated plants and animals.
Roger Gates is the agricultural and natural resources agent for University of Georgia Extension, Whitfield County. Contact him at email@example.com.