四季竹立竹表型可塑性的林分密度效应

Responses of Oligostachyum lubricum phenotypic plasticity to the changes of stand density

为了给优良的观赏和夏秋笋用竹种四季竹的丰产林分密度建立提供理论依据,开展了四季竹纯林4种林分密度(17500～27500株·hm-2,D1;37500～42500株·hm-2,D2;55000～62500株·hm-2,D3;72500～82500株·hm-2,D4)的分株构件因子调查,并对立竹主要形态特征因子进行了主成分分析。结果表明:随着林分密度的增大,四季竹立竹胸径和相同胸径下的节间长分别呈"∧"和"∨"形变化,极值分别出现在D3和D2密度。相同胸径下的立竹冠幅和枝盘数均呈"∨"形变化,并且最小值都出现在D2密度;立竹枝长和残枝率均呈倒"N"形变化,枝长最大值和残枝率的最小值均出现在D3密度。林分叶面积指数呈"∧"形变化,最大值出现在D3密度;立竹单叶面积与林分密度呈显著正相关。相同胸径下的立竹全高、胸高壁厚、枝下高和枝夹角、单叶质量、比叶面积在不同林分密度间无显著差异。经主成分分析,立竹表型形态与秆形构件关系最为密切,其次为枝条构件,最后是叶片构件。经通径分析,各林分密度立竹表型综合得分大小顺序为:D3>D4>D2>D1。在试验林立竹胸径条件下,D3是四季竹无性系生理整合成本和效益的密度阀值,是分株形态良好建成的适宜林分密度。

In order to supply theoretical references for establishing high-yield stand density of Oligostachyum lubricum, an excellent ornamental and edible shoot bamboo species in summer and autumn, an investigation was made on the ramet components at four stand densities （17500-27500 stems·hm^-2, D1; 37500-42500 stems·hm^-2, D2; 55000-62500 stems·hm^-2, D3; and 72500-82500 stems·hm^-2, D4）, and the obtained data were analyzed by principal component analysis. With the increase of stand density, the diameter at breast-height （DBH） and the internode length with the same DBH varied in the shapes of ＂∧＂ and ＂∨＂, with the extreme value at D3 and D2, respectively. The crown width and the round of branches with the same DBH varied in ＂∨＂ shape, with the minimum value at D2, while the branch length and the incomplete branch rate varied in shapes of inverse ＂N＂, respectively, with the minimum value at D3. The leaf area index varied in ＂∧＂ shape, with the maximum value at D3. There was a positive correlation between area per leaf and stand density. No significant differences were observed in the total height, wall thickness at breast height, height under branch, angle between branch and stem, dry weight per leaf, and specific leaf area among D1, D2, D3, and D4. Principal component analysis indicated that the phenotypic characteristics of O. lubricum were most closely correlated with ramet stem, followed by with twig, and foliage. Through path analysis, the phenotypic comprehensive score was in the order of D3D4D2D1. It was considered that at the current DBH of ramets in experimental forest, D3 was the threshold density value between the cost and benefit of physiological integration, and the best stand density for planting O. lubricum.