杉木幼龄林分断面积生长的良种与密度效应研究

Effects of Improved Varieties and Densities on Stand Basal Area Growth of Young Chinese Fir(Cunninghamia lanceolata)Plantation

[目的]探讨不同良种和初植密度对杉木幼龄期断面积生长的影响及其互作效应,以揭示在这两个控制因子下杉木林断面积生长发育规律。[方法]以2012年春在福建省邵武卫闽国有林场营造的杉木良种和初植密度互作试验林为研究对象,根据8年的逐年定位观测资料,分析2个杉木种子园良种(第1代种子园良种和第3代种子园良种)和4种初植密度(1667、3333、5000、6667株·hm^(-2))控制下的林分断面积生长动态效应。[结果]初植密度对林分断面积生长具有极显著影响,同一林龄下,初植密度越高,林分断面积生长愈大。林分断面积生长的良种效应差异不显著,但低初植密度下(1667和3333株·hm^(-2)),第3世代良种的断面积生长要高于第1世代良种,且随林龄增长这种现象愈明显。方差分析结果表明良种和初植密度间交互效应不显著,多重比较结果表明:低初植密度下,良种对断面积生长的正效应和密度对断面积生长的正效应具有叠加效应,且随林龄增长这种叠加效应愈明显,而高初植密度下(5000和6667株·hm^(-2)),不同良种和密度组合下的断面积生长差异不显著。[结论]低初植密度下,杉木幼龄林分断面积生长的良种和密度效应具有叠加效应,第3世代良种初植密度为3333株·hm^(-2)的断面积生长显著高于第1世代良种初植密度为1667株·hm^(-2),随初植密度增大,良种对林分断面积生长的影响程度逐渐减弱。

[Objective] To study the effects of improved varieties and initial planting densities on stand basal area growth of young Chinese fir(Cunninghamia lanceolata) plantation and their interaction, so as to explore the basal area growth of Chinese fir plantation controlled by the two factors. [Method] The improved varieties-initial planting densities interactive trial forest of Chinese fir was established in Weimin State-owned Forestry Farm, Shaowu, Fujian Province in 2012. Based on 8-years’ positioning observation data of interactive trial forest, the effects of two improved varieties(first generation seed orchard and third generation seed orchard) and four planting densities(1 667,3 333, 5 000, and 6 667 trees·hm-2) on stand basal area growth of Chinese fir plantation were analyzed. [Result] The effect of initial planting density on the growth of stand basal area was very significant. At the same age level, the stand basal area growth became larger with the increase of initial planting density. The improved varieties had no significant effect on the stand basal area growth. However, under the lower initial planting densities(1 667 and 3 333 trees·hm-2), the stand basal area growth of the third generation seed was higher than that of the first generation seed,and this phenomenon became more obvious with age. The results of variance analysis showed that the interaction between the initial planting densities and improved varieties had no significant effect on the stand basal area growth.But the results of multiple comparisons showed that under the lower initial planting densities, the positive effect of improved varieties and initial planting densities had an addictive effect on the stand basal area growth, and the addictive effect was more obvious with age. But under the higher initial planting densities(5 000 and 6 667 trees·hm-2), the effect of different combinations of the improved varieties and initial planting densities on stand basal area growth was not significant. [Conclusion] Under the lower initial planting densities, improved varieties and initial planting densities have an addictive effect on stand basal area growth of young Chinese fir plantation, the stand basal area growth of the third generation seed with 3 333 trees·hm-2 is significantly higher than that of the combination of the first generation seed and1 667 trees·hm-2. The effects of improved varieties on stand basal area growth decrease with the initial planting densities increase.