表栖跳虫和螨类群落对高寒草甸退化的响应

Responses of the epigeic springtails and mites to the degradations of alpine meadow

为查明高寒草甸退化对表栖跳虫和螨类群落组成及多样性的影响,于2018年7月和10月利用吸虫器法对若尔盖湿地的沼泽草甸、草原草甸及中度退化草甸三种生境的表栖跳虫和螨类进行了调查。捕获表栖跳虫13640只,隶属于4目11科23属,优势类群为小圆跳属和德跳属;捕获表栖螨类5069只,隶属于3亚目76科98属(类),优势类群为真足螨科。主成分分析结果表明,表栖跳虫和螨类群落组成在不同生境间存在明显差异。随高寒草甸退化程度加重,表栖跳虫仅群落密度显著增加(P<0.05),而表栖螨类的群落密度和类群数均显著增加(P<0.05)。在3个生境中,表栖跳虫群落密度和Simpson优势度指数均表现为7月显著高于10月(P<0.05),类群数和Shannon指数则是7月显著低于10月(P<0.05);表栖螨类的群落密度和类群数均表现为7月显著高于10月(P<0.05),Shannon指数和Simpson优势度指数无显著季节变化(P>0.05)。冗余分析和多元回归分析结果表明,植物种类、生物量、土壤容重等是影响表栖跳虫和螨类群落结构及多样性的主要因子,但对表栖跳虫和螨类的具体影响存在差异。研究表明,高寒草甸的表栖跳虫和螨类群落组成、密度及多样性存在明显的时空变化,其中表栖跳虫群落密度及多样性对季节变化较敏感,表栖螨类群落密度和类群数对高寒草甸的退化较敏感。

To understand the effects of alpine meadow degradation on the composition and diversity of epigeic springtail and mite communities,we investigated epigeic springtail and mite communities in swampy meadow,grassland meadow,and moderately degraded meadow of Zoige wetland using motor-sucking in July and October 2018.A total of 13640 springtail individuals,belonging to 4 orders,11 families and 23 genera,were collected,with Sminthurinus and Desoria being the dominant taxon.A total of 5069 mite individuals,belonging to 3 suborders,76 families and 98 genera(taxonomic groups),were collected,with Eupodidae as the dominant group.Results of principal component analysis showed that the taxonomic composition of springtail and mite communities differed remarkably among different habitats.With increasing degradation degree,the abundance and taxonomic richness of mites increased(P<0.05),the abundance of springtails increased significantly(P<0.05).The abundance and Simpson index of springtails were significantly higher in July than those in October(P<0.05)across the three habitats,while the opposite patterns were found for the taxonomic richness and Shannon index.Regarding to epigeic mites,the abundance and taxonomic richness were significantly higher in July than those in October(P<0.05),without seasonal variation in Shannon and Simpson dominance index(P>0.05).The results of redundancy analysis and multiple regression analysis showed that the taxonomic composition,abundances and diversity index of epigeic springtails and mites were mainly influenced by the specie richness and biomass of plant communities and soil bulk density,but the effects differed between springtails and mites.Our results demonstrated that degradation and seasonal changes had significant effects on the taxonomic composition,abundance and diversity index of epigeic spring-tail and mite communities.The springtails responded more sensitively to seasonal changes than mites,and the mites were more significantly affected by the degradation of alpine meadows than springtails.