关键词: FACE, C₄植物, 稗草, 光合作用, 适应, 气孔导度

Abstract: In order to provide a theoretical basis for establishing a high-productive Oligostachyum lubricum stand, this paper studied the aboveground biomass accumulation, allocation and the allometric pattern of 1-3 yearold O. lubricum at four stand densities (24600-29800 stems·hm^-2, D1; 37500-42600 stems·hm^-2, D2; 46500-52800 stems·hm^-2, D3; and 76500-85500 stems·hm^-2, D4) with basically the same DBH. The allocation proportion of the O. lubricum modular biomass was in the order stem>branch>leaf. With the increasing age of the O. lubricum, the modular biomass and aboveground biomass as well as the leaf/branch, leaf/stem, and branch/stem ratios at the four stand densities all had an increasing trend, and were significantly higher for 2 and 3-year-old O. lubricum than for 1-year-old O. lubricum. The allocation proportion of the branch and leaf biomass presented an increasing trend, while that of the stem biomass was in adverse. With the increasing stand density, the modular biomass and aboveground biomass of 1-3-year-old O. lubricum were overall in “∧” shape, i.e., increased gradually at stand densities D1-D3 but decreased significantly at stand density D4. The allocation proportion of the leaf and branch biomass of 1-3-year-old O. lubricum decreased, while that of the stem biomass increased. The leaf/branch, leaf/stem, and branch/stem ratios of 1-year-old O. lubricum were in inverse “N” shape, while those of 2- and 3-year-old decreased on the whole. The leafbranch biomass accorded with near-constant growth model, and the allometric index decreased slightly with increasing stand density; whereas the leaf-stem biomass and the branch-stem biomass accorded with simple allometric model, and their allometric indices presented a trend of increasing and of decreased after an initial increase with the increase of the stand density, respectively. All the results indicated that when the stand density was higher than 37500-42600 stems·hm^-2, more biomass was tended to allocate in stem to promote the longitudinal growth to obtain more light resource, and the suitable stand density for the high-efficient biomass accumulation and allocation was 46500-52800 stems·hm^-2.