National Public Radio: In a 19th-century farmhouse deep in northern Pennsylvania`s Bradford County, Nancy Baker is looking at family photos dating back four generations.
One shows her grandfather with a team of horses on clear cut land. Another shows her mother and aunt on the same farm as a small child. Baker also has a series of aerial photos going back to 1939, which show how the forest cover has evolved in the past 70 years.
Her home was built by her great grandfather, Joseph Morrow Gamble, a Scots-Irish immigrant...