三峡库区马尾松天然林林分结构特征分析

以三峡库区无干扰马尾松天然林为研究对象,调查了群落物种组成和天然更新状况,并选择角尺度、混交度和大小比数3个空间结构参数及直径分布等非空间结构参数,对马尾松天然林林分结构特征进行分析,为马尾松次生林的科学经营提供理论依据。研究结果表明:研究地区马尾松群落物种数量丰富,共出现维管束植物117种,林下天然更新状况良好,共有树种24种,数量达5 221株·hm^-2,其中高度小于100 cm的幼苗占48.9%。林分随着直径增大,林木株数逐渐减少,呈典型异龄林直径分布特征。林分平均角尺度为0.508,林木整体分布格局属随机分布;林分平均混交度为0.60,整体处于中度以上混交;林分平均大小比数为0.50,大部分林木个体分化程度较高,处于不同竞争地位的林木个体数量基本相等。优势树种马尾松属轻度聚集分布,接近中度混交,且60.2%的个体处于竞争优势或亚优势地位。

Analysis on Structure Characteristics of Pinus massoniana Natural Forest in the Three Gorges Reservoir Area

In order to provide a theoretical basis for scientific management of Pinus massoniana secondary forest, the undisturbed P. massoniana natural forest was selected in the Three Gorges Reservoir Area to investigate the species composition and natural regeneration. The stand structure characteristics of P. massoniana were analyzed using spatial structure and non-spatial structure indictors such as uniform angle index, mingling, neighborhood comparison and diameter distribution. The results showed that the species number was abundant. There were 117 vascular plant species in the stand. The stand natural regeneration was good, and the regeneration number was 5 221 per hectare including 24 species, and the number of seedlings which were lower than 100 cm accounted for 48.9% of the total number of regeneration trees. The tree number decreased with increasing diameter, and the feature of stand diameter distribution followed a typical uneven-aged forest character. The stand mean angel index was 0.508, and the pattern of individual tree horizontal distribution was random. The stand mean mingling was 0.60, and the stand was medium mingling. The stand mean neighborhood comparison was 0.50. Most of the individual trees were clearly different, and the number of individual tree which on different competitive position was almost same. The distribution of P. massoniana was cluster, and the mingling was close to medium, and 60.2 percentage trees were dominant or subdominant in the stand.