亚热带喀斯特地区不同地形植物群落物种多度分布格局

为探究亚热带喀斯特地区不同地形下植物群落物种多度分布格局,揭示不同地形下群落的物种多度格局形成的作用机制,丰富该地区植物群落构建理论,该文以贵州茂兰喀斯特地区山脊、槽谷、鞍部、洼地4种典型地形下植物群落的乔木层与灌木层为对象,统计物种多度,采用累计经验分布曲线(ECDF)表征多度分布格局,采取Wilcoxon秩和检验探究不同地形之间物种多度的差异性。采用不同生态学模型进行多度拟合,利用Kolmogorov-Smirnov(K-S)检验与赤池信息量准则(AIC)检验模型接受与拟合优度。结果表明:(1)不同地形下植物群落的个体数量与物种数存在差异,鞍部个体数最多,洼地的物种数最多,山脊的个体数、物种数均最少。(2)不同地形下植物群落的乔木层物种多度格局无显著差异,灌木层之间出现显著差异,山脊与鞍部、洼部,鞍部与槽谷、洼部都存在显著差异。(3)不同地形下乔木层物种多度对中性模型接受较好,其中山脊拟合最优,对生态位模型接受较差,仅山脊与鞍部通过两种生态位模型,拟合优度不及中性模型。灌木层对中性模型接受也较好,鞍部拟合最优,对生态位模型接受较差,仅洼地通过断棍模型。整体而言,乔木层比灌木层能更好地接受两种生态学模型,可能乔木层物种多度格局有更明显生态过程的印记,但不同地形下灌木层拟合优度差异更大,可能与灌木层物种对环境变化更剧烈有关。不同地形会引起群落构建不同程度的生态学过程,物种多度分布格局会逐渐适应地形。

Species abundance distribution pattern of plant communities in different terrains in subtropical karst area

In order to explore of the species abundance distribution(SAD)pattern of plant communities under different terrains in subtropical karst area, to reveal the SAD formation mechanism of the community under different terrains, and to enrich the theory of plant community construction in this area, the arbor layer and shrub layer of plant communities under four typical landforms of ridge, trough valley, saddle and depression in Maolan karst area of Guizhou Province were used as the objects. The empirical cumulative distribution function(ECDF)was used to characterize the SAD, at the same time, the Wilcoxon rank sum test was used to analyze the differences in species abundance between different terrain. Then different ecological models were used for fitting, and Kolmogorov-Smirnov(K-S)test and Akaike Information Criterion(AIC)were used to detect model acceptance and goodness of fit. The results were as follows:(1)There were differences in the number of individuals and species in plant communities under different terrains, the number of individuals in saddles was the most, the number of species in depressions was the most, and the number of individuals and species in ridges was the least.(2)There were significant differences among shrub layers, between ridge and saddle, between ridge and depression, between saddle and trough valley, and between saddle and depression, while there were no significant differences in the SAD of arbor layers in plant communities under different terrains.(3)The SAD of the arbor layer under different terrains was well accepted by the neutral model. The ridge fitted best, but all terrains were poorly accepted by ecological models, only the ridge and saddle passed through the two niche models, and the goodness of fit was not as good as that of the neutral model. The shrub layer was also well accepted by the neutral model with the best fit of the saddle, but it was poorly accepted by the niche model, and only the depression passed the broken stick model. Overall, the arbor layer was more acceptable to the two ecological models than the shrub layer, probably because the SAD of the arbor layer had more obvious imprints of ecological processes. However, the difference in the goodness of fit of the shrub layer under different terrains is greater, which may be related to the more drastic changes of the shrub layer species to the environment. Consequently, different terrains lead to different ecological processes of community construction, and the SAD pattern gradually adapts to the terrain.