Seed Production and Dissemination
Good seed crops occur every 3 to 8 years, with light crops during intervening years (22). Red spruce cones number about 140/liter (5,000/bu), which yields 454 to 680 g (1.0 to 1.5 lb) of seeds. The number of cleaned seeds per kilogram ranges between 220,000 and 637,000 (100,000 and 289,000/lb), with an average of about 306,000 (139,000/lb) (41).
Red spruce seeds fall about 1.2 m (4 ft) per second in still air; the following formula determines distance of travel for wind- disseminated spruce seeds at various heights (47):
D = Sh (1.47v)
Where D = distance in feet which seed will travel, S = number of seconds required for seed to fall from a height of h (ft) on a tree, and v = velocity of the prevailing wind in miles per hour.
Randall (37), in a study of seed dispersal into clearcut areas, stated that at a distance of 100 m (5 chains or 330 ft) from the timber edge, the number of spruce seeds trapped were more than adequate for regeneration in a good seed year and adequate in an average year. Most of the spruce in the surrounding stands was red spruce.