轮伐期对杉木人工林地力维护的影响

通过对全国杉木中心产区不同发育阶段杉木人工林生长及生物量的调查，研究轮伐期对杉木人工林生物量及养分分布规律的影响，结果表明：不同轮伐期经营的杉木林林分生物量及其养分分配规律存在差异，随年龄阶段的提高，杉木枝、叶、根、边材及林冠所占比例逐年下降，干、皮和心材比例逐年增加，边材／心材及林冠／树干比例下降，轮伐期越短，每采伐单位杉木干物质所带走的养分越多，对地力的消耗越严重；同时短轮伐期还造成采伐、炼山

EFFECT OF ROTATION ON SITE PRODUCTIVITY MAINTENANCE OF CHINESE FIR PLANTATION

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.