杉木材种结构及大径材生长保留密度与立地效应

Effect of Retention Density and Site Quality on Species Structure and Large-diameter Growth Retention in Chinese Fir Plantation

以29 a生不同立地指数和保留密度的杉木林分为研究对象,分析各林分材种结构和大径材生长规律.结果发现:林分平均单株材积随着保留密度的增加呈下降趋势,蓄积量呈先增加后减小趋势.从林分材种结构看,杉木大径材主要集中于24~30 cm径阶.小径材出材量、出材率随保留密度的增加而增加,随地位指数的增加而减小;中径材出材量、出材率随保留密度的增大而增加,随地位指数的增加而减小;大径材出材量随保留密度的增大先增加后减小,随地位指数的增加而增加,出材率随保留密度的增大而减小,随地位指数的提高而增加.保留密度在1000~1200株/hm^(2),大径材出材量和出材率均较大(保留密度1100株/hm^(2)最大),低密度和高地位指数更适合培育杉木大径材.

The 29-year-old existing Chinese fir forests with different site indexes and retention densities were researched as objects,and the timber assortments structure and large-diameter timber growth laws of each forest were analyzed.The results showed that the average volume per tree decreased with the increase of retention density,the volume increased first and then decreased.According to the timber assortments structure of stand,large diameter wood of Chinese fir is mainly concentrated in 24~30 cm diameter class.The timber production rate and volume of small diameter wood increased with the increase of retention density and decreased with the increase of site index,while that of medium diameter wood increased with the increase of retention density and decreased with the increase of site index.The output of large diameter wood increased at first and then decreased with the increase of retention density,increased with the increase of site index,and the yield decreased with the increase of retention density and increased with the increase of site index.When the retention density is in the range of 1000~1200 plants/hm^(2),the output and yield of large diameter wood are higher(the retention density is 1100 plants/hm^(2)),the low density and high site index are more suitable for cultivating large diameter wood of Chinese fir.