关键词: 轮伐期, 杉木, 长期生产力, 地力衰退

Abstract: The distributions of biomass and nutrients in different rotation plantations of Chinese fir are studied by the investigation of different aged plantations in the central productive area of Chinese fir. The results are as follows: There are significant differences among Chinese fir plantations of different rotations concerned with stand biomass(SB) and nutrients distribution. The ratios of branch/SB, leaves/SB, root/SB, sapwood/SB, canopy/SB, sapwood/heartwood and canopy/stem decrease gradually and the ratios of stem/SB, bark/SB and heartwood/SB increase as the age increases. The shorter rotation is, the more nutrients are taken away per unit biomass by harvesting and the more nutrient of soil is consumed. Moreover, short rotation results in increase of soil disturbing frequency by cutting, control burning and site preparation and inhibition of its underground vegetation development. Therefore, rotation is an important factor influencing the site productivity of Chinese fir plantation. The ecological mature age of Chinese fir must be taken into consideration in the future and rotation should be prolonged in order to offer plantation a period for site nutrient recovery and buffer the pressure on the site by plantation management.

Key words: Rotation, Chinese fir, Long-term productivity, Soil degradation