Eco-friendly guests gathered for the anniversary celebration of the NatureConservancy at the Corcoran Gallery of Art on Sept. 10. “In Response to Place:Photographs From the Nature Conservancy,” an exhibition by a dozennoted artists and photographers, including Annie Leibovitz, William Wegman,Sally Mann and William Christenberry, was previewed by more than 500 guests.Actress Joanne Woodward, who serves on the organization’s board, was onhand for the festivities. The exhibit documents some of the organization’s mostremarkable protected sites.