摘要
该项试验共分 2个部分。 (1)造林密度试验 ,小区面积为 6 0 0m2 ,5个处理 ,即 16 6 7株·hm- 2(A)、3333株·hm- 2 (B)、4 983株·hm- 2 (C)、6 6 33株·hm- 2 (D)、996 7株·hm- 2 (E) ;(2 )造林密度调控试验 ,造林设计方法与造林密度试验相同 ,但在林分生长过程中 ,按密度管理图的密管线 0 5为标准进行间伐 ,间伐后保留密度要与临近的下一个初植密度较稀植的林分密度基本相同 ,两者进行比较。试验结果 :(1)造林密度试验 ,优势高、平均高、平均胸径均随年龄的增加而递增 ,随密度的增加而递减 ,优势高 9a、平均高 6a、平均胸径 5a ,密度间差异已达显著性水平 ;林分蓄积量则随年龄增加而递增 ,5 7a ,密度间差异显著 ,8 18a ,只有A密度与E、D密度差异显著 ;枝下高随密度、年龄的增加而递增 ,12a后 ,C、D、E密度间的差异很小 ;冠幅随密度的增加而递减 ,随年龄的增加而递增 ,9 10a后 ,各密度则随年龄增加而缓慢递减。 (2 )造林密度调控试验 ,同一指数级 ,间伐后的林分与其密度基本相同未间伐的林分比较 ,其优势高、平均高差异不明显 ;立木蓄积前者小于后者 ;总蓄积 (立木蓄积+间伐蓄积 )前者大于后者 ;同一指数级 ,初植密度不同的林分 ,间伐后与密度基本相同未间伐林分的蓄积百分比 ,初植密度大的大?
There are three parts in this research, including the effects of different planting density, different thinning intensity and planting density thinning on the growth of Chinese fir stand. (1)Planting density experiment consist of five density treatments:A(1 666 trees·hm -2 ), B(3 333 trees·hm -2 ),C( 5 000 trees·hm -2 ), D(6 666 trees·hm -2 ) and E(10 000 tress·hm -2 ). The result of experiment shows that the dominant height, average height and diameter at breast height (DBH)of stands increases with the increase of stand age, and decreases with the increase of stand density. The dominant height after age 9, average height after age 6 and DBH after age 5 have evident differences among different stand densities. Stand volume increase with the increase of stand age, and it reaches evident difference from age 5 to 7 among different densities, but it only has remarkable differences between A and E or D from age 8 to 18. The tree height under first branch increases with the increase of stand density and trees age, the difference among C,D and E are not obvious after age 12. The crown diameter decreases with the increase of stand density, and increases with the increase of trees age, the differences among different stand densities decreases after age 9 10. (2)The primary planting density for the thinning test of planting density is same as the planting density experiment, thinning methods are that C is reduced to D and D is reduced to E after thinning. The results shows that at same site index class, comparing the unthinned stand with the thinned stand which keeps the same density with the unthinned stand after thinned, their average height and dominant height has no evident difference, but the standing tree volume of thinned stand is lower than that of unthinnned stand, the total volume (standing tree volume + thinned tree volume) of thinned stand is higher than that of unthinned stand, the ratio of total volume of thinned stand with high primary density to unthinned stand is higher than that of thinned stand with low primary density to unthinned stand. At the same primary density, the ratio of volume thinned stand to unthinned stand at the high site index class is higher than that at the low site index class.
出处
《林业科学研究》
CSCD
北大核心
2002年第1期66-75,共10页
Forest Research
基金
国家攻关专题"杉木建筑材树种遗传改良及大中径材培育技术研究"(96 0 11 0 3 0 1)
关键词
杉木林
造林密度
密度调控
林分生长
Chinese fir
planting density
density control
growth of stand
