Regeneration waves are an unusual type of continual, wave-form mortality known only from high-altitude balsam fir forests in the northeastern U. S. and Abies veitchii forests in Japan. Recent studies in wave-regenerated forests have shown that (1) the "3/2 thinning law" describes the relationship between bole weight and stand density well, but is less successful when applied to total above-ground weight; (2) natural rates of self-thinning appear to decrease with stand age; (3) total above-ground net primary productivity does not decrease as expected in old high-altitude fir forests, casting some doubt on the widely held belief that tree respiration increases as stands age; (4) nutrient accumulation in biomass is rapid in the early stages of stand development but then slows down; and (5) nutrient availability exceeds demand in the early stages of stand development but falls behind after crown closure, so that a nutrient shortage develops which is greatest during the period of maximum productivity and biomass accumulation and decreases later.
It is suggested that fully-developed wave-regenerated forests can occur only where there is (1) a directional stress; (2) no other large-scale disturbance, and (3) a tree species which is both shade-tolerant and short-lived.