- Crawford, Hewlette S
Northeastern Forest Experiment Station, USDA
- Titterington, Richard W.
University of Maine
Upland spruce-fir forest types in north- eastern and north-central United States and Maritime and southern Canada are largely commercial forests, supporting major wood-using industries. In the United States, most of this forest land is privately owned; in Canada, there is more public ownership. However, in both cases, forest cutting is a major factor that modifies bird habitat structure and influences bird populations.