砂质潮土施用改良剂对土壤动物群落特征的影响

Effects of Amendments on Soil Fauna Community Characteristics in a Fluvo-Aquic Sandy Soil

【目的】土壤动物是陆地生态系统中重要组成部分。研究土壤动物与农田施用有机、无机改良剂的关系,有助于揭示改良剂对土壤动物的影响机制。【方法】2016—2019年,在小麦玉米轮作区土壤中设施用有机改良剂15 t·hm^(-2)(YJ)、无机改良剂2.25 t·hm^(-2)(WJ)、有机改良剂15 t·hm^(-2)+无机改良剂2.25 t·hm^(-2)(YW)和未施改良剂(CK)4个处理,研究其对0—20 cm表层土壤动物群落组成与多样性的影响。【结果】研究时段,共采集到土壤动物4351只,隶属8纲20目41科44类。其中,大型土壤动物28类,食虫虻科和切叶蚁亚科为优势类群,占所捕获大型土壤动物总数的62.9%;中小型土壤动物14类,螨和甲螨亚目为优势类群,占所捕获中小型土壤动物总数的93.0%。土壤动物营养功能类群以腐食性和杂食性为主。数据显示,WJ处理土壤动物个体数和类群数最多,YJ处理的最少。与CK相比,施用改良剂后土壤中幺蚰科、绥螨科、蛱科等的数量减少且丰富度指数降低,而蜱螨类动物数量增大而优势度指数偏高。不同年度间,土壤中小型动物群落的个体数量和多样性指数存在显著差异(P<0.05),且个体数呈现逐渐上升的趋势。不同处理间,Jaccard指数(q)均小于0.50,大型土壤动物群落相似性均低于中小型土壤动物群落的相似性。改良剂干扰下螨、甲螨亚目和棘跳科等中小型土壤动物生态位宽度偏高,切叶蚁亚科等大型土壤动物生态位宽度普遍较小,但生态位重叠指数均大于0.97,显示施用改良剂后土壤动物共有资源增加。非度量多维尺度法(NMDS)分析显示,2018年小麦季土壤动物群落与其他年份之间差异显著,玉米季2016年与2018、2019年间有差异。冗余分析(RDA)分析发现,小麦季土壤全氮、有效钾是影响土壤螨类、甲螨亚目、棘跳科、奇蝽科、步甲科数量的主要因子(P<0.05);玉米季土壤有机质、pH是影响土壤螨类、奇蝽科、尖眼覃蚊科、食虫虻科的主要因子(P<0.05)。主效应曲线(PRC)分析表明,有机改良剂处理下,尾足螨科的相对多度在2017年10月达到峰值,食虫虻科和切叶蚁亚科的相对多度在2016年10月达到峰值;有机无机改良剂配施处理下,棘跳科、螨和甲螨亚目的相对多度在2016年10月达到峰值,管蓟马科和奇蝽科在2019年出现并在2019年10月达到峰值,显示土壤动物类群对改良剂的响应不一致。【结论】改良剂对土壤动物的影响低于年度间变化,且主要通过影响土壤pH、有机质和全氮含量,从而影响砂质潮土中动物群落特征。

【Objective】Soil fauna is an important component of terrestrial ecosystem,therefore,the studying of the relationship between soil fauna and amendments will help reveal the mechanism of amendments to soil fauna.【Method】During 2016-2019,the characteristics of the soil fauna community in the soil surface layer(0-20 cm)of wheat and maize rotation area with different amendments were investigated.There were four treatments,including no amendment(CK),organic amendment 15 t·hm^(-2)(YJ),inorganic amendment 2.25 t·hm^(-2)(WJ)and organic amendment 15 t·hm^(-2)+inorganic amendment 2.25 t·hm^(-2)(YW).【Result】During the study period,4351 soil fauna belonging to 8 classes,20 orders,41 families,and 44 classes were collected,of which 28 families were macrofauna,and the dominant groups were Asilidae and Myrmicinae,accounting for 62.9%of the total captured soil macrofauna.In another,14 families soil meso-and micro-fauna were collected,and the dominant groups were Acarid and Oribatida,accounting for 93.0%of the total captured soil meso-and micro-fauna.Soil fauna mainly belonged to saprozoic and omnivores.The data indicated that the total number and taxa of soil fauna collected during the experiment was the highest under WJ,and the lowest under YJ.The number of Scutigerellidae,Sejidae and Japygidae decreased and their richness index decreased,while the mites increased,and the dominance index was high under amendments comparing with CK.There were significant differences in individual number and diversity index of small and medium animal communities among different years(P<0.05),and the number of individuals showed a gradually increasing trend;but the Jaccard index(q)of soil fauna was less than 0.50 among all treatments,and the similarity of macrofauna community was lower than that of meso-and micro-community.The ecological niche widths of mesoand micro-soil fauna,such as Acarid,Oribatida,and Onychiuridae,were higher than those of macrofauna,such as Myrmicinae.However,the niche overlap index was higher than 0.97,indicating that the application of amendments increased the common resources of soil fauna.The NMDS analysis showed that the soil animal community in wheat season 2018 was significantly different from that in other years,whereas,in maize season of 2016,2018,and 2019,there were different.The results of RDA indicated that soil TN and AK were significantly correlated with Acarid,Oribatida,Onychiuridae,Enicocephalidae,Carabidaein wheat season(P<0.05);the soil organic matter and pH were main factors influencing Acarid,Enicocephalidae,Sciaridae,and Asilidae in maize season(P<0.05).The PRC analysis showed that the relative abundance of Uropodidae peaked in October 2017,and that of Asilidae and Myrmicinae peaked in October 2016 under YJ.The relative abundance of Onychiuridae,Acarid,and Oribatida reached a peak in October 2016 under the combined application of organic and inorganic amendments,and that of Phlaeothripidae and Enicocephalidae appeared in 2019 and peaked in October 2019,demonstrating the incongruity of soil fauna groups to the amendments.【Conclusion】The variation of soil fauna community and diversity in different years were much more profound than amendments,and the amendments modified soil fauna community and diversity mainly by changing soil pH,SOM,and TN in a fluvo-aquic sandy soil.