环境因子对甘南高寒草甸地表大型节肢动物多样性的影响

Characteristic of Ground-Dwelling Macroarthropods Community in Alpine Meadow of Gannan Region

地表节肢动物是生态系统的重要生物指示物,研究甘南高寒草甸地表节肢动物群落多样性与环境因子的关系,有助于揭示其分布格局对高寒草甸生态环境变化的响应。2018年5至9月,采用陷阱法调查甘南高寒草甸4种典型类型生境,即沼泽湿地、沼泽化草甸、草甸和成熟草甸地表大型节肢动物群落组成与多样性。研究时段共采集地表大型节肢动物2545头,属于3纲9目29科30属,以狼蛛属(Lycosa)、弓背蚁属(Camponotus)和蚁属(Formica)为优势类群。营养功能群以捕食类和植食类为主。研究结果显示,成熟草甸生境大型节肢动物类群数明显高于沼泽化草甸和草甸生境的类群数(P<0.05);沼泽湿地生境Pielou均匀度指数(Js)明显大于草甸和成熟草甸生境的Pielou均匀度指数(P<0.05);Shannon-Wiener多样性指数(H′)差异不显著(P>0.05);4种生境之间地表大型节肢动物群落相似性指数较低。研究时段基于物种“出现-不出现”C-score、V-ratio、SES与Pianka生态重叠指数的实测值与预测值的差异均没有规律性,显示研究区域地表大型节肢动物群落随机性与竞争性格局共存,受随机扩散与生态过滤共同影响。置换多元方差分析(Per MANOVA)表明,研究区域生境特征(R^(2)=0.6364,P<0.001)比研究时间(R^(2)=0.1573,P<0.001)能更多地解释地表大型节肢动物群落变化。土壤主要理化性质显著地影响了地表大型节肢动物群落特征,其中,土壤温度和土壤含水量对地表大型节肢动物群落影响最大。基于距离的冗余分析(db-RDA)结果表明,土壤理化性质与地上生物量仅共同解释了地表大型节肢动物群落变异的29.88%,其他70.12%的变异没有得到解释,显示地表大型节肢动物群落形成的复杂性。

[Objectives]Ground-dwelling macroarthropods are important indicators of soil ecosystem.Studying the characteristics of community of ground-dwelling macroarthropods in alpine meadows is helpful to reveal the response of its distribution pattern to the change of alpine meadow ecological factors.[Methods]From May to September 2018,we investigated ground-dwelling macroarthropods community composition and diversity by pitfall traps at four typical alpine meadow habitats(swamp wetland,swamp meadow,meadow and mature meadow).The principal coordinate analysis(PCoA)was used to explain the similarities or differences in ground-dwelling macroarthropods community from different habitats.Permutational multivariate analysis of variance(PerMANOVA)tests the significance of community distinctions among habitats and sampling time.Variance partitioning analysis(VPA)was used to evaluate the soil environmental factors,above ground biomass and sampling time on ground-dwelling maroarthropods community.The influence of specific soil environmental factors on the dynamics of ground-dwelling maroarthropods community structure was analyzed by distance-based redundancy analysis(db-RDA).[Results]A total of 2545 individual ground-dwelling macroarthropods were collected from May to September 2018,belonged to 30 genera of 29 families,9 orders,3 classes.The dominant groups were Lycosa,Camponotus and Formica,and predators and herbivores were dominant in trophic groups(Table 2).The number of ground-dwelling macroarthropod groups in habitat of mature meadow was significantly higher than that of habitats of swamp meadow and meadow(P<0.05);the Pielou evenness index(Js)of habitat of swamp wetland was significantly higher than that of habitats of meadow and mature meadow(P<0.05);Shannon-Wiener diversity index(H′)had no significant difference(P>0.05)among habitats,and the similarity index of ground-dwelling macroarthropod communities between habitats was low(Table 3).Among the Checkerboard score of the matrix(C-score),variance ratio(V-ratio),standardized effect size based on binary data,the Pianka niche overlap,the difference between the observed and simulated values have not regularity,suggesting that the ground-dwelling macroarthropods community assemblage was randomness and competition coexist,and that is structured simultaneously by both random diffusion and ecological filtering(Table 5).PerMANOVA analysis showed that the habitat characteristics of the study area(R^(2)=0.6364,P<0.001)could more explain the changes of the ground-dwelling macroarthropods community characteristics than seasons(R^(2)=0.1573,P<0.001).The characteristics of the ground-dwelling macroarthropods community was affected significantly by soil physicochemical properties,of which soil temperature and soil moisture content have the greatest impacts(Fig.2).The distance based on redundancy analysis(db-RDA)showed that the soil physicochemical properties and aboveground biomass explained 29.88%of the variation of the ground-dwelling macroarthropods community,while the other 70.12%of the variation was not explained,indicating the complexity of the formation of the ground-dwelling macroarthropods community(Fig.3).[Conclusion]The result showed that the ground-dwelling macroarthropods community changed with different habitats and seasons.The effects of habitats on ground-dwelling macroarthropods composition were much greater than those of seasons.