The longleaf pine ecosystem is a temperate coniferous forest ecosystem found within the Southern United States. Spanning pine savannas, sandhills and montane forests, it includes many rare plant and animal species, and is one of the most biodiverse in North America. Once one of the largest ecosystems in North America, from Virginia south to Florida and west to Texas, it now occupies less than a quarter of the original range. Degradation of the ecosystem is partially due to excessive timber harvesting, urbanization, and fire exclusion. Although the ecosystem is heavily fragmented at present, it still carries a great diversity of plant and animal species, many of which are endemic. A range of techniques, including planting longleaf pine seedlings, introducing prescribed burning regimens, managing native ground cover, and controlling invasive species within the ecosystem, are used in attempting to preserve this threatened ecosystem.