Abstract: 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 D3>D4>D2>D1. 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.

Key words: Atmospheric CO₂ enrichment, Soil microbes