Longleaf pine was once one of the most ecologically important tree species in the Southern United States. Longleaf pine and its accompanying forest ecosystems covered vast swaths of the Southern United States, spanning an estimated 60-90 million acres. One estimate places the historical extent of long leaf pine forests at 92 million acres. Although once one of the most extensive forest ecosystems in North America, only a fraction of these longleaf pine forests remain today.