成熟杉木人工林林下草本层生态位特征

Niche characteristics of understory herb layer in a mature Chinese fir plantation

生态位是解释群落中种间共存与竞争机制的基本理论,对了解植物群落构建及其与环境因子的耦合关系具有重要意义。本文通过对成熟杉木(Cunninghamia lanceolata)人工林林下草本层植物调查,应用Shannon和Levins生态位宽度指数、Levins生态位重叠指数以及生态响应,分析了杉木人工林林下草本层植物生态位特征。结果表明:成熟杉木人工林草本层植物生态位宽度不高。狗脊(Woodwardia japonica)的B(SW)(3.6254)和B(L)(0.7069)生态位宽度指数均最大,其主要原因是分布广泛,适应性强。生态位宽度较大的狗脊和玉叶金花(Mussaenda pubescens)与其他优势物种间具有相对高的生态位重叠度。总体上,杉木人工林林下草本层物种的生态位重叠度偏低,物种对环境资源的共享能力弱。草本层主要优势物种绝大部分处于发展性阶段,表明现阶段的杉木人工林群落趋于相对稳定状态。

The niche theory is widely used to explain the interspecific coexistence and competition mechanisms in the communities, which is of significance for understanding the coupling between plant community assembly and environmental factors. By investigating the herbaceous communities in the understory of mature Chinese fir plantation （Cunninghamia lanceolata）, Shannon, Levins niche width indexes, Levins niche overlapping indexes and ecologieal responding were used to analyze the niche characteristics of the herbaceous plants. The results showed that the niche width of the herbaceous plants in the mature Chinese fir plantation was not high. The niche width index of B（sw） （3.6254） and B（L）（0.7069） were the largest for Woodwardia japonica due to its wide distribution and strong adaptation to environment. W. japonica and Mussaenda pubescens with large niche width had higher niche overlapping with other dominant species. In general, relatively lower niche overlapping among species were apparent in the herb layer in the understory of Chinese fir plantation, indicating that the ability of species for sharing resources was weak. Our study suggested that most of the dominant species of herbaceous plants were in developing stage due to low niche overlapping, and that Chinese fir plantation eommunity tended to be relatively stable.