Greentree Foundation (New York-based) was created in 1982 and "supports charitable, educational and scientific programs." 
"Through an adaptive management plan developed with the Greentree Foundation, The Nature Conservancy will work to conserve and protect Greenwood as the highest quality example of a longleaf pine wiregrass ecosystem in the Red Hills and the East Gulf Coastal Plain Ecoregion. After one year, the Foundation expects to transfer title to the Conservancy." 
"Oliver Hazard Payne purchased the property in 1899, and left the Plantation to his nephew, "Plain" Payne Whitney. When the latter died in 1927, the estate passed to his widow, Helen Hay, daughter of the Lincoln biographer, John Hay. Her son, John Hay Whitney, inherited Greenwood Plantation in 1944 and worked with pioneering foresters Ed and Roy Komarek, Herbert Stoddard and Leon Neel to manage the forest while preserving the integrity of the ecosystem. Their techniques of prescribed burning and sustainable forestry resulted in the special character and ecological value of this property today. John Whitney’s wife, Betsey, donated the property upon her death in 1998 to the 'Greentree Foundation, which Mrs. Whitney established in 1982 after the death of her husband."