黑龙江省不同纬度梯度农田大型土壤动物群落分布特征

沿着由高到低的纬度梯度,分别在塔河、带岭、帽儿山的农田生境选择研究样地,采用手捡法调查不同纬度农田生态系统大型土壤动物的群落组成、水平结构、垂直结构和多样性特征,并运用双变量相关分析及典范对应分析阐明土壤动物群落和环境因子的相互关系,旨在揭示黑龙江省不同纬度梯度农田大型土壤动物群落分布特征及其影响因素。调查共捕获大型土壤动物35类2339只,隶属于2门6纲14目35科。其中线蚓科(Enchytraeidae)、正蚓科(Lumbricidae)、步甲科(Carabida)、隐翅虫科(Staphylinidae)为优势类群,其个体数占总个体数的58.84%;常见类群为蚁科(Formicidae)、蜘蛛目(Araneida)和地蜈蚣目(Geophilomorpha)等8类,其个体数占总个体数的32.79%。结果表明:(1)水平分布上:大型土壤动物个体密度和丰富度(即类群数)的水平分布均表现为帽儿山带岭塔河,单因素方差分析表明大型土壤动物的个体密度和丰富度在不同纬度地区无显著差异。Shannon-wiener多样性指数(H')和Pielou均匀度指数(E)均为帽儿山带岭塔河;Simpson优势度指数(C)表现为塔河和带岭最高,帽儿山最少;Margalef丰富度指数(D)则是塔河最多,其次为帽儿山和带岭。(2)垂直分布上:3个不同纬度样地的农田土壤动物个体密度和丰富度在同垂直层次间不存在明显差异(P0.05)。除帽儿山5—10 cm土层土壤动物类群数量较表层增加之外,其他样地大型土壤动物个体密度和丰富度均随土层深度的增加而逐渐降低,表聚性明显。(3)与土壤环境因子关系上:双变量相关分析表明,不同纬度农田大型土壤动物的类群数、个体密度、多样性指数、均匀度指数和优势度指数与土壤p H值、有机质、全氮、全磷和速效磷均没有显著的相关性;典范对应分析(CCA)进一步表明,优势类群和常见类群对环境因子具有较强的适应能力,广泛的分布在3个样地内。研究表明,农田生态系统大型土壤动物的类群数、个体密度和多样性指数随纬度梯度的增加先增加后减少,但不同纬度间均无显著性差异。不同土壤动物类群受到环境变量的影响程度不同,在局地尺度环境因子对土壤动物的影响不容忽视。研究为区域尺度农田生态系统土壤动物空间格局和生物多样性维持机制研究奠定基础。

Distribution characteristics of soil macro-faunal communities along a latitudinal gradient in farmland of Heilongjiang Province

Spatial patterns of soil faunal communities at a regional scale are important foundations for the maintenance and protection of belowground biodiversity. Although many studies have addressed the spatial patterns of soil animal communities in different habitats, few have focused on the spatial patterns along latitudinal gradients. In this study, we determined the composition, horizontal structure, vertical structure, and diversity characteristics of soil macrofaunal communities in farmland systems along a latitudinal gradient. We selected three representative mountain areas along the latitudinal gradient:the Maoer Mountains (Maoer Mountain ecosystem station, 45°20''-45°25''N, 127°30''-127°34''E), the Xiaoxing''an Mountains (Dailing,47°10''-47°14''N, 128°53''-128°55''E), and the Da Hinggan Mountains (Tahe, 52°09''-53°23''N,123°19''-125°48''E). In each study area, three farmlands at least 50 m apart with similar conditions were randomly selected. In each farmland, four plots (5 m×5 m) were randomly delineated. In each plot, four soil profiles (50 cm×50 cm) were randomly collected and divided equally into three 5 cm strata to survey the soil macrofaunal communities. The hand picking method of separation was used to determine the soil macrofaunal communities. Fieldwork was conducted in August 2011. Using bivariate related analysis and canonical correspondence analysis, we assessed the relationships between soil animal communities and environmental factors. In total, 2339 individuals from 35 groups of soil animals were collected, which belonged to 2 phyla, 6 classes, 14 orders, and 35 families. Enchytraeidae, Lumbricidae, Carabidae, and Staphylinidae were dominant families, accounting for 58.84% of the total number of individuals. Formicidae, Araneidae, and Geophilomorpha were common groups, accounting for 32.79% of the total number of individuals. The results showed that:(1) In terms of horizontal distribution, individual density and richness (i.e. numbers of groups) at sites followed the order Maoer Mountain > Dailing > Tahe. Results of the one-way ANOVA revealed there were no significant differences in individual density or richness in the soil macrofaunal communities at different latitudes. The Shannon-Wiener diversity index (H) and Pielou evenness index (E) for sites followed the order Maoer Mountain > Dailing > Tahe. The Simpson dominance index (C) of Tahe and Dailing were higher than that of the Maoer Mountains, and the Margalef richness index (D) was greatest in Tahe, followed by the Maoer Mountains and Dailing. (2) In terms of vertical distribution, no significant differences were detected among the three different latitudinal areas for individual density or richness at the same vertical level (P < 0.05). Individual density and richness in soil macrofaunal communities decreased with increasing soil depth, except for soil macrofaunal communities from the Maoer Mountains at 5-10 cm, indicating an obvious surface aggregation. (3) Regarding the relationships between soil macrofaunal communities and soil environmental factors, the bivariate correlation analysis showed there were no significant correlations among richness, individual densities, diversity indices, evenness indices, richness indices, pH values, organic matter, total nitrogen, total phosphorus, and available phosphorus. Results of canonical correspondence analysis further indicated that the dominant and common groups were highly adaptable to environmental factors and the dominant and common groups were widely distributed in the three latitudinal areas. This study showed that the numbers of groups, individual densities, and diversity indices of the soil macrofaunal communities from the farmland ecosystem changed along a latitudinal gradient, but no significant changes were found in this study. Different soil animal groups at different latitudes are affected by environment variables. At the local scale, the influence of environmental factors on soil macrofauna should not be ignored. The results of the study create a foundation for researching spatial patterns and mechanisms of biodiversity maintenance at regional scales.