不同采伐强度对云冷杉天然林主要针叶树种生长的影响

以云冷杉天然速生丰产林的12块固定样地为研究对象,研究不同采伐强度(对照、20%、30%、40%)对全林及不同林层的主要针叶树种(红松、云杉、冷杉)的断面积生长率、蓄积生长率的影响。结果表明:采伐与对照相比,能显著促进林分生长,全林及各林层的断面积生长率和蓄积生长率均大于对照,全林及第Ⅰ、Ⅱ林层的断面积和蓄积生长率随采伐强度的增加先增后减,第Ⅲ林层的断面积和蓄积生长率随采伐强度的增加而增加。所有样地中,断面积和蓄积生长率由大到小的排序为:第Ⅲ林层、第Ⅱ林层、全林、第Ⅰ林层。在伐后6、9 a,不同采伐强度的全林和第Ⅰ、Ⅱ林层的断面积和蓄积生长率之间的差异性显著,而第Ⅲ林层的差异性不显著。采伐过的样地各林层生长率均大于对照样地同林层的生长率,其中采伐强度为30%的样地的第Ⅱ、Ⅲ林层的生长率与对照样地差异性显著。故采伐强度为30%的森林经营措施更有利于天然云冷杉林的伐后恢复生长。

Effects of Different Cuttings on Growth of Primary Coniferous Species in Natural Spruce-fir Forest

With 12 fixed sample plots with different cutting intensity ( 20%, 30%, and 40%) in natural spruce-fir forest, we studied the effects of different cutting intensities on basal area and volume growth rate of primary coniferous species ( Kore-an, spruce, and fir) in stand and tree layers.Compared with the control ( cutting intensity of 0%) , different cuttings had significant effects on the stand growth and the basal area, and the volume growth rates of the stand and tree layers of prima-ry coniferous species in different cutting intensity stands were higher than that in the control stand.The basal area and vol-ume growth rates of the whole stand, first tree layer and second tree layer were increased with the increase of cutting inten-sity, but when the cutting intensity reached a certain value, it was reduced.However, the basal area and volume growth rates of the third tree layer was increased with the increase of cutting intensity.Among all stands, the growth rate descend-ing order of basal area and volume was the third tree layer, the second tree layer, the whole stand, and the first tree layer. After six-and nine-year cutting, the difference of basal area and volume growth rates of the whole stand, first tree layer and second tree layer among different cutting intensity stands was significant, but the difference in third tree layer was not significant.The growth rates of basal area and volume for three tree layers under different cutting intensities were higher than that in the control stand.The growth rates of first tree layer and second tree layer of stands with the cutting intensity of 30%differed significantly with that of the control stand.Therefore, the cutting intensity of 30%was more conductive to the growth recovery of natural spruce-fir forest after cutting.