Research Paper (RP)
Two good, three heavy, and two bumper spruce seed crops were produced during a 15-year period. There was considerable variability in seed crops, however. Not all locations produced good to bumper seed crops when overall yearly ratings averaged good or better; conversely, some locations produced bumper seed crops in 3 or more years. Mathematical relationships, that should be useful in estimating potential sound seed production, were estimated between periodic annual15-year sound seed production and (1) periodic annual15-year total seed production and (2) selected stand parameters of dominant and co-dominant spruces.
Alexander, Robert R.; Edminster, Carleton B.; Watkins, Ross K. 1986. Estimating potential Engelmann spruce seed production on the Fraser Experimental Forest, Colorado. Res. Pap. RM-RP-269. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 7 p.