Study on the Change Laws of Biomass of Chinese Fir Plantations

Based on study materials of 3 biomass research in the similar site condition of Dagangshan forest region and the observed materials of permanent sample plots of Chinese fir, this paper made a relatively detailed study on the change laws of biomass of Chinese fir plantations, and obtained the main results as follows: (1)For the same stands, except that biomass of leaves and some branches have a decreasing duration(from 5 a to 8 a), biomasses of various parts of mean individual and stand all increase with the increasing of stands age, during the quick growth years of stands, the proportions of leaves, branches and stem are weakly increasing, with above ground parts increasing and roots decreasing. In stem growth stage(12～16 a), the proportion of each organ of mean individual tends to be stable. (2)Site indices have obvious affection on the amount of biomass, biomasses of all parts and allocation rate of mean individual and stand, the affection varies with stand age, and is restricted by planting density. (3)With the increasing of planting density, the biomass of each organ of mean individual obviously decreases, the allocation rate of biomass of stem tends to decrease at any age; the discrepancies of biomasses of different stands, caused by planting density, tend to decrease with the increasing of stand age.