杉木人工林材种结构的立地及密度效应研究

采用30年生未间伐的杉木人工林连续观测数据,研究了不同林龄立地质量、林分密度对林分材种结构的影响。结果表明:初植密度相同时,立地质量越好各材种出现时间及达到最大出材率的时间越早,22立地指数初植密度1 667株·hm^-2的小径材最大出材率出现时间较16立地指数初植密度1 667株·hm^-2早4 a,中径材最大出材率出现的时间早6 a;立地指数相同时,随初植密度增加小径材出材率的峰度及峰值均减小,20立地指数样地中,初植密度为1 667株·hm^-2的小径材出材率峰值较初植密度为10 000株·hm^-2的高17%,而初植密度对中径材、大径材影响不大;在林分发展的不同时期,林分密度对材种出材率的影响不同,30年生时林分蓄积相近的但初植密度不同的样地,初植密度越大小径材出材率越高,大径材出材率越低。

Effects of Site Quality and Planting Density on Wood Assortment Rate in Chinese Fir Plantation

The continuous observation data from 30 year-old permanent sample plot was studied. The effects of site quality and stand density on small-, middle- and large-diameter timber outturn rate were analyzed. The results suggested: 1.In the plots with same planting density, the stand quality was better, every timber assortment and the maximum outturn rate appeared earlier. In A3 plot with site index of 22, the maximum outturn rate appeared 5 year earlier than that in A1 plots with site index of 16; 2.The kurtosis and maximum value of small-diameter wood outturn rate decreased with planting density increasing. The maximum value in A2 plot with site index of 20 was higher than that in E2 plot. But, planting density had little effects on middle-diameter and large-diameter timber; 3.In different period of stand development, the stand density had different effects on timber assortment outturn rate. At 30 years old stand, the timber assortment rate in plots with similar stand volume was significant different. With the planting density increasing, small-diameter timber outturn rate increased and large size timber outturn rate decreased.