鼎湖山不同植被类型下土壤肉足虫群落结构的比较研究

为了解不同植被类型下土壤原生动物群落的特征,采用定性和定量培养法,对采自鼎湖山国家级自然保护区内沟谷常绿阔叶林(A点)、河岸常绿阔叶林(B点)、温带季风常绿阔叶林(C点)、针阔叶混交林(D点)、针叶林-马尾松林(E点)、山地常绿阔叶林(F点)和山顶灌草丛(G点)7种植被下土壤样品中肉足虫的群落组成和数量进行了观察和统计;并借助"普遍分布模型(ubiquity model)"和"生物地理模型(biogeography model)"理论,探讨了土壤原生动物在较小范围内的分布模式。结果显示:在所有土壤样品中,共检出20属31种土壤肉足虫,其中Centropyxis和Nebela属出现的物种数最多(各有3种);在全部肉足虫种类中,有8种出现在4个土壤样点中,它们分别是Amoeba sp.、Centropyxis compressa、Difflugia globulosa、D.gramen、Lamtopyxis sp.、Nebela dentistoma、Trinema enchelys和T.lineare。对比分析显示:不同植被下的土壤肉足虫群落组成呈一定差异,F点土壤中肉足虫最多(15种),G点土壤中最少(9种);不同植被类型下土壤肉足虫群落的丰度差别很大,最高出现在F点中(29 200 ind./g),最低出现在G点中(3 510 ind./g)。群落相似性比较显示:各样点的土壤肉足虫群落处于中等不相似(0.25~0.5)到中等相似(0.5~0.75)的水平。聚类分析表明,A点与F点的土壤肉足虫群落相似性最高;B点与G点的土壤肉足虫群落相似性也较高;D点与其他5个样点的相似性相对较低。单因子相关性分析显示土壤含水量与肉足虫丰度间有极显著的相关性(P0.01),而土壤中NO_3~–-N与肉足虫丰度间有显著的相关性(P0.05);多元相关分析表明,鼎湖山土壤肉足虫丰度变化与多个土壤理化因子组合间存在相关性,以(pH+含水量)组合与土壤肉足虫丰度的相关性最大。CCA分析显示不同的土壤理化因子对肉足虫某具体种的作用存有差异。因此,鼎湖山自然保护区土壤肉足虫的分布更符合"生物地理模型"。

Comparative Study on Community Structure of Sarcodina in Soils Under Different Vegetations in the Dinghu Mountain

In order to understand the characteristics of soil protozoa communities under different vegetations, soil samples were collected from 7 different vegetations in Dinghu Mountain, the community composition and abundance of soil Sarcondina were studied with the methods of qualitative and quantitative cultivation and the distribution pattern of soil Sarcondina in the small range was investigated based on the ubiquity model and biogeography model. In total 20 genera and 31 species of soil Sarcondina were found in the soil samples, and the Genus Centropyxis andNebela were found to harbor the most species (both 3 species). Among all species,Amoeba sp.,Centropyxis compressa,Difflugia globulosa,D. gramen,Lamtopyxis sp.,Nebela dentistoma,Trinema enchelys andT. lineare were found in four sites. There were distinct differences in soil Sarcondina community composition under different vegetations, there most species (15 species) were observed under evergreen broad-leaved forest in the montane (Sample F) and the least species (9 species) under shrub and grass near to top of mountain (Sample G). There were various abundance distributions of soil Sarcondina communities under different vegetations, the highest abundance of soil Sarcondina was in Site F (29200 ind./g) and the lowest was in Site G (3510 ind./g). The Sarcodina community similarity index was in the level from moderate unsimilarity (0.25 - 0.5) to moderate similarity (0.5 - 0.75). Cluster analysis showed that the highest community similarity was found between the Sample A (evergreen broad leaved forest in valley) and Sample F (evergreen broad-leaved forest in montane), and community similarity between Sample B (evergreen broad-leaved forest in riparian) and Sample G (the shrub and grass near to top of the mountain) was higher, meanwhile the relatively lower community similarity between Sample D (coniferous and broad-leaved mixed forest) and other samples were noticed. Correlation analysis revealed that there was an extremely significant correlation (P<0.01) between soil water content and the abundance of the Sarcodina, and there was a significant correlation between soil NO– 3-N and the abundance of the Sarcodina (P<0.05). The multiple correlation analysis showed that there were correlations between the abundance of the soil Sarcodina and the combinations of soil physic-chemical factors, particularly with soil pH and water content. CCA analysis showed that different soil physical and chemical factors had different affects on different Sarcodina species. The results displayed the distribution of soil Sarcodina in Dinghu Mountain was consistent with Foissner "biogeography model".