小型表栖节肢动物群落对高寒湿地退化的响应

为查明小型表栖节肢动物群落对高寒湿地退化的响应,2014年7月和9月利用吸虫器法对若尔盖高寒湿地的沼泽草甸、草原草甸、中度退化草甸3种生境的小型表栖节肢动物群落进行调查。结果为:共采集到小型表栖节肢动物18661只,隶属于3纲15目85类(科或属),优势类群为球圆跳属(Sphaeridia)、长跳属(Entomobrya)和莓螨科(Rhagidiidae),其中长跳属仅出现在草原草甸。小型表栖节肢动物群落结构在不同生境间差异明显,主成分分析(PCA)结果表明影响群落结构的主要类群是长跳属(Entomobrya)、球圆跳属(Sphaeridia)、齿步甲螨属(Odontocepheus)、瘤蚜科(Pemphigidae)和叶蝉科(Jassidae),但不同月份间存在差异。小型表栖节肢动物的群落密度及类群数均以草原草甸最高,中度退化草甸最低,3种生境间有显著差异(P0.01)。3种生境的小型表栖节肢动物群落密度均是7月显著低于9月(P0.01),Shannon-Wiener指数和Simpson优势度指数则是7月显著高于9月(P0.01);类群数在沼泽草甸中7月显著低于9月(P0.05),在草原草甸和中度退化草甸则是7月显著高于9月(P0.05)。典范对应分析(CCA)及多元回归分析结果表明植物种类、生物量、土壤有机质含量是影响小型表栖节肢动物群落组成结构、密度及多样性的主要因子。研究结果表明高寒湿地退化能够显著影响小型表栖节肢动物群落的组成结构、密度和多样性及其季节动态。

Responses of epigeic microarthropods to alpine wetland degradation

Three typical habitat types, swampy meadow, grassland meadow, and moderately degraded meadow, were selected in Zoigê wetland and epigeic microarthropods were investigated using motor-sucking machine in July and September 2014. The aim of this study was to reveal the responses of epigeic microarthropods to the degradation of alpine wetland. A total of 18661 epigeic microarthropod specimens were collected during the research periods and classified into 3 classes, 15 orders, and 85 taxonomic groups (families or genus). The results showed that Sphaeridia, Entomobrya, and Rhagidiidae were the dominant taxonomic groups, and that Entomobrya were only present in grassland meadow. The structural composition of epigeic microarthropod communities differed markedly among the three different degradation stages. Principal component analysis results showed that the community structure was determined by Entomobrya, Sphaeridia, Odontocepheus, Pemphigidae and Jassidae. Maximum values of abundances and taxonomic richness were obtained for the grassland meadow, and minimum values were recorded in the moderately degraded meadow. Significant differences were detected among the abundances and taxonomic richness of the three habitats (P < 0.01). The monthly dynamics in taxonomic richness of the epigeic microarthropod communities also differed among the three habitats (P < 0.01). For all three habitats, microarthropods were significantly more abundant in July than in September. Shannon-Wiener and Simpson dominant indices were higher in July than in September, although the differences were not significant (P < 0.01). The number of taxonomic groups of epigeic microarthropods was significantly lower in July than in September in the swampy meadow (P < 0.05), whereas it was significantly higher in July for the grassland and moderately degraded meadows (P < 0.05). The results of canonical correspondence and multiple regression analyses showed that the composition, abundances, and diversity of epigeic microarthropod communities were affected by the factors of species richness, biomass of plant communities, and contents of soil organic matter. The results indicated that in addition to changes in seasonal patterns, the degradation of alpine wetland has had significant effects on the composition, abundance, and diversity of the epigeic microarthropod communities.