Ecological definitions of old-growth Douglas-fir forests

Franklin, Jerry F.; Spies, Thomas A. 1991. Ecological definitions of old-growth Douglas-fir forests. In: Ruggiero, Leonard F.; Aubry, Keith B.; Carey, Andrew B.; Huff, Mark H., tech. eds. Wildlife and vegetation of unmanaged Douglas-fir forests. Gen. Tech. Rep. PNW-285. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 61-69.