小陇山锐齿栎原始群落林木径阶空间结构特征

运用固定样地每木定位调查和林分空间结构分析软件,分析锐齿栎原始林群落中主要树种不同大小林木的分布格局、树种隔离程度和大小分化程度。锐齿栎原始林群落林分中小径阶个体较多,林分整体径阶分布呈倒“J”型,建群种锐齿栎径阶分布呈正态分布;林分平均角尺度为0.542,建群种锐齿栎种群整体上呈轻度的聚集分布,幼苗幼树呈中度聚集分布,中径木呈随机分布,大树则呈轻度聚集分布。光叶泡花树种群和小叶鹅耳枥种群,幼苗幼树呈聚集分布向随机分布过渡状态,而中径木则呈聚集分布,川鄂鹅耳枥、地锦槭、鄂椴和水榆花楸种群不同径阶的林木个体呈不同程度的聚集状态;鹅耳枥种群幼苗幼树和中径木个体呈轻度聚集分布,大树个体则呈均匀分布。林分的平均混交度为0.700,属于中度混交与强度混交的过渡状态,随着种群个体胸径大小的增加,川鄂鹅耳枥和锐齿栎种群的混交度逐渐减小,地锦槭、鹅耳枥和鄂椴种群则随着胸径大小的增加,混交度先降低后增加,水榆花楸、光叶泡花树和小叶鹅耳枥种群的混交度随着个体大小的增加而逐渐升高。建群种锐齿栎的平均大小比数为0.166,在林分中处于优势地位;光叶泡花树在小树阶段更具有竞争优势,各主要树种的优势度排列顺序为:锐齿栎、鹅耳枥、地锦槭、鄂椴、川鄂鹅耳枥、水榆花楸和光叶泡花树。该样地的群落特征可为小陇山林区锐齿栎次生林的经营指明方向,指导小陇山林区锐齿栎次生林经营。 

Analysis of spatial structure characteristics based on diameter class of trees in primeval Quercus aliena var acuteserrata community in the forest area of Xiaolong Mountain,Gansu Province

Using the software of single tree sampling in a fixed plot and stand structure analysis,we explored the distribution pattern, isolation and size differentiation for different sizes of dominant tree species in Quercus aliena var. acuteserrata virgin forest community in the forest area of Xiaolong Mountain in Gansu Province, western China. There were more medium and small sized individuals in Q. aliena var. acuteserrata virgin forest community, stand diameter class distribution was of inverted “J” type, and the diameter class for constructive species Q. aliena var. acuteserrata population followed a normal distribution. The stand mean uniform angle index was 0. 542. The individual distribution for constructive species of Q. aliena var. acuteserrata population was slightly aggregated, for seedlings and saplings it was moderate aggregation, for medium diameter trees it was a random distribution and for large trees it was a slightly aggregated distribution. The seedling and sapling individuals of Meliosma cuneifolia var. glabriuscula and Carpinus turczaninowii var. stipulata population showed the transition state from aggregated distribution to random distribution, and their medium diameter trees aggregated distribution. Individuals of Carpinus henryana, Acer mono, Tilia oliveri and Sorbus alnifolia population in different diameter classes showed different degrees of aggregation distribution. The seedling and sapling and medium-diameter individuals of Carpinus turczaninowii population showed aggregated distribution and its large individuals showed uniform distribution. The average mingling of stand was 0. 700, belonging to transient state from the moderate to strong mixture. The mingling of C. henryana and Q. aliena var. acuteserrata population decreased with the increase of DBH, and the mingling of Acer mono, C. turczaninowii, and T. oliveri population decreased first and then increased with the increase of DBH. The mingling of S. alnifolia, M. cuneifolia and C. turczaninowii var. stipulata population increased with the increase of DBH. The mean value of neighborhood comparison of Q. aliena var. acuteserrata was 0. 166 and in the dominant position in stand. The seedlings and saplings of M. cuneifolia var. glabriuscula were more competitive than other species. The order of dominance of dominant tree species from high to low was Q. aliena var. acuteserrata, C. turczaninowii, A. mono, T. oliveri, C. henryana, S. alnifolia and M. cuneifolia var. glabriuscula. The community characteristics of this plot can be used as the direction and guidance for the management of Q. aliena var. acuteserrata secondary forest in Xiaolong Mountain.