闽北乐东拟单性木兰天然林群落结构与多样性

Structure and plant species diversity of a natural forest community of Parakmeria lotungensis in Northern Fujian Province,China

采用相邻格子法设置样地,对闽北邵武乐东拟单性木兰天然林群落结构与多样性进行研究。结果表明:以乐东拟单性木兰为优势建群种的天然林群落共有维管束植物42科63属86种;群落乔木、灌木层发达,而草本层发育差;群落中高位芽植物占优势(87.21%),而高位芽植物中,以小高芽植物比例最大,其次为中高芽;群落不同层次的物种丰富度(S)、Shan-non-Wiener指数(H')及其Pielou均匀度指数(Jsw)、Simpson多样性指数(D)及其Pielou均匀度指数(Jsi)均为灌木层>乔木层>草本层>层外植物。乐东拟单性木兰种群有较多的幼苗幼树(2434株·hm-2),有一定数量的大树(75株·hm-2),但小树数量少(97株·hm-2),种群结构在中树阶段出现断层。虽然目前群落较稳定,但经过长期的演替,乐东拟单性木兰可能被其他更加耐阴的常绿阔叶树种所取代。

The plant community of a natural forest with dominant tree species of Parakmeria lotungensis, located in Shaowu, northern Fujian Province, China was sampled by contiguous quadrats technique and the community structure and species diversity were studied. The results showed that there were 42 families of vascular plants ineluding 63 genera and 86 species in the natural forest of P. lotungensis （ study area 2 000 m^2 ）. There were highly developed tree and shrub layers and poorly developed herb layer in the community. Phanerophytes （87.21%） were dominant life form in this eommnuity, and mierophanerophytes were dominant in phanerophytes, followed by mesophanerophyte. Species richness, Shannon-Wiener and Simpson＇s indices and their Pielou＇s evenness indices of plant diversity were in the order： shrub layer 〉 tree layer 〉 herb layer 〉 vine species. There were abundant seedlings （2 434 stems · hm^-2）, some big trees （75 stems· hm^-2）, but few young trees （97 stems · hm^-2）, no middle trees in the P.lotungensis population. Population structure of P. lotungensis was fragmented at middle-tree stage. Although the community was stable then, but P.lotungensis might be replaced by other shade-tolerant evergreen broad-leaved tree speeies in the long-term succession.