Changes in biomass components through stand development in wave-regenerated balsam fir forests

Abstract

Available data on the wave-regenerated Abiesbalsamea forests of the northeastern United States are synthesized into a model (BALSAM) which predicts changes in total and component biomass through the disturbance–regeneration cycle. Measured decay rates seem to imply a higher mean forest floor mass than is actually observed, so several alterations were made in the initial model to make it predict forest floor mass correctly. With or without these changes, forest floor mass decreases for about 12 years after disturbance, largely owing to low levels of litterfall in the early stages of stand development. Because changes in living biomass and dead bole mass through the disturbance cycle roughly cancel each other out, net ecosystem productivity closely parallels these litterfall-driven changes in the forest floor. Throughout the disturbance–regeneration cycle, the forest floor is derived primarily from woody tissue and its decay products, with foliage-derived material making up less than 25% of the total forest floor mass.