红松洼自然保护区土壤螨群落结构对短期围栏封育的响应研究

Soil Mite Community Structure in Response to Short-Term Grazing Exclosure and Characteristics as Indicators of Environmental Quality in Hongsongwa Natural Reserve

草原生态系统中土壤螨是最具优势的土壤动物类群之一,具有很高的生物多样性,因此,在进行土壤环境变化的评价和监测时,应充分考虑土壤螨在物种水平上的多样性和群落结构特性。为了解红松洼自然保护区土壤螨群落结构和多样性特征及其对短期围栏封育的响应,筛选出可用于草原生态系统的监测和评价指标特征,设置固定研究样地进行围栏封育,采用样方法对围栏内封育区和围栏外自由放牧区土壤螨群落结构和多样性进行调查。结果表明围栏内土壤螨种数(41种)比围栏外(21种)多近1倍,其中,无气门、前气门、中气门和甲螨分别由围栏内的6、6、7和22种下降为围栏外的3、2、3和13种;围栏内较围栏外的物种数-样点数量关系曲线更好地拟合了"物种数-样点数量双曲线关系方程",围栏内a/b值(44)是围栏外的(12)近4倍;优势种棘下盾螨(Hypoaspis queerlandicus)的表土层密度围栏内比围栏外高2.9倍,围栏内、外表土、中层、底层垂直密度比分别为44:8:1和3:3:1,表聚垂直分布型发生了明显变化;围栏内中气门和棘下盾螨的雄性密度分别比围栏外高25.7%和6.7%。这些结果说明:物种丰富度、物种数-样点数量关系、优势种棘下盾螨密度垂直分布和捕食螨雄性密度指标特征较敏感,可作为草原生态系统土壤质量的监测和评价指标。本研究首次报道了红松洼自然保护区土壤螨的种类名录和组成结构特征,为进一步的研究和方法的建立奠定了基础。

Soil mites are one of the most dominant and diverse soil mesofauna groups in prairie ecosystems and therefore soil mite diversity and community structure at the species level should be fully considered in assessment and monitoring of the soil environment. An experiment was conducted to determine the response of the soil mite community structure and species diversity characteristics to short-term grazing exclosure in Hongsongwa Natural Reserve by comparing the communities inside and outside the exclosure fence, and their characteristics as bioindicators. Both the exclosed area and the surrounding area with continuous grazing area were studied with the quadrat method. The results showed that the total species number of soil mites inside the fence （41 species） exceeded that outside the fence （21 species） by ca. 50%, and the accumulative curves of “species number vs. sample point number” indicated that the mite species number continuously increased with increasing number of sample points inside the fence, but this was not the case with grazing; the density of the dominant speciesHypoaspis queerlandicus in the soil surface layer （0~5 cm） inside the fence exceeded that outside the fence by 2.9 times, and the density ratios of surface/middle （5~10 cm）/bottom （10~15 cm） layer were 44：8：1 and 3：3：1 respectively for inside and outside the fence. These selected bioindicators were the most sensitive to absence of grazing. Shannon-Wiener diversity index and densities of male Mesostigmata were also higher in the exclosures; total density and densities of groups and species, and male to female ratios of Mesostigmata responded to the grazing exclosure, but their sensitivity was less than the above characteristics. During the two years of exclosure, the bioindicator characteristics of soil mite community diversity showed different levels of sensitivity, suggesting that they could be used for assessment or evaluation of soil quality of prairie ecosystem. The present study reports on soil mite species and their composition in the Hongsongwa Natural Reserve, laying the foundation for further scientific research and methodological studies.