Here in the Eastern US we are trying to reintroduce chestnut trees after they were almost completely killed off by a blight. The project involves finding survivor stock in the wild and crossing it with a line of hybrid trees that were selected for blight resistance. The survivor trees are usually small, hard to see, and deep in the forest, but they hold their leaves and stay green later into the Autumn than other types of trees. Do you think you could find photos of central Pennsylvania in the September and October when most trees are turning red, yellow, and orange? We would need to look for patches of deciduous trees that are still green. They would probably be on hilltops in dense forest.