The Diversity Of Soil Collembolan Community And Its Responses To Disturbance From Exogenous Carbon And Nitrogen In Black Soil Area

Collembolan (Hexapoda: Collembola) are among the most widespread and abundantterrestrial arthropods. They play an important role in accelerating the rate of decomposition ofsoil organic matter, improving the potential soil carbon sequestration and soil fertility, and soon. The abundance and diversity of soil collembolan could be affected, directly or indirectly, byexternal disturbance, such as inputting exogenous carbon and nitrogen to soil. This couldundermine their functional role in the soil ecosystem, and further affect the ecosystemfunctions associated with soil collembolan. Therefore, a study of the dynamic changes in soilcollembolan community richness and diversity and their response to exogenous carbon andnitrogen has great significance in revealing the functional role of soil collembolan in theprocess of decomposition and mineralization of soil organic matter.In this paper, dynamic changes in the richness and diversity of soil collembolancommunities and their response to disturbance with exogenous carbon and nitrogen werestudied in a field experiment in the black soil area; thereafter greenhouse pot experiments wereconducted to investigate the relationship among soil collembolan community diversity, soilmicrobial community structure and soil properties in response to disturbance by exogenouscarbon and nitrogen. The main results were as follows:1. In the field experiment, the methods of modified Tullgren and Baermann were used tosurvey the composition and structure of soil collembolan as affected by exogenous carbon andnitrogen in2011and2012. A total of270soil samples and42634soil collembolan individualswere collected and sorted into12families.The effects of exogenous carbon and nitrogen and sampling time on soil collembolancommunity diversity were significant. The number of soil collembolan individuals subjected todisturbance by exogenous carbon was higher than the number subjected to disturbance ofexogenous nitrogen. In2011, the number of soil collembolan individuals rose from May to August and declined in September; in2012, the number of soil collembolan individualsdeclined from May to September. A principal component analysis (PCA) showed that thecomposition of soil collembolan was related to sampling time and type of exogenousdisturbance.Soil properties, such as temperature, moisture, pH, organic carbon, total nitrogen and thecarbon to nitrogen ratio, were influenced by exogenous carbon and nitrogen. Compared to acontrol treatment (CK), soil temperature, moisture, carbon and soil total nitrogen increased by6.59%~9.16%,1.16%~6.26%,9.43%~26.37%and7.93%~21.01%, respectively. Soil fertilitywas improved with disturbance by exogenous carbon. The soil carbon-nitrogen ratio wasreduced and the rate of decomposition of organic matter was accelerated with disturbance byexogenous nitrogen, which was not conducive to the accumulation of organic material.Soil collembolan community diversity was influenced by the changed soil properties. Aredundancy analysis (RDA) showed that soil collembolan communities were affectedsignificantly by soil temperature, soil moisture, soil organic carbon and total nitrogen (p<0.05),the influence of soil moisture was greatest.2. In the greenhouse pot experiments, the method of denaturing gradient gelelectrophoresis was used for the first time to survey the diversity of soil collembolancommunity. The results showed that the richness of soil collembolan communities wasinfluenced significantly by exogenous carbon and nitrogen and sampling time (p<0.01). Further,the richness of soil collembolan communities varied over season. The richness in May wasdifferent significantly with that in June, July and August (p<0.05); and the richness in N1.5wassignificantly different from that in the control treatment (CK)(p<0.05).Using the method of phospholipid fatty acids to survey the composition and structure ofsoil microbial community as affected by exogenous carbon and nitrogen, the results showedthat the total PLFAs was increased in the treatments of exogenous carbon, decreased in thetreatments of exogenous nitrogen, and influenced significantly by exogenous substances andsampling time (p<0.01). And the results of Pearson correlation analysis showed that the total PLFAs was correlated significantly with soil total nitrogen (p<0.05). The bacterial PLFAs,fungal PLFAs, arbuscular mycorrhizal fungi PLFAs, gram-positive bacterial PLFAs andgram-negative bacterial PLFAs were also increased in the treatments of exogenous carbon anddecreased in the treatments of exogenous nitrogen. The soil microbial communities weresignificantly influenced by soil moisture, temperature and pH (p<0.05), and the influence ofpH was greatest (p<0.01).The influences of exogenous substances, soil properties, and soil microbial on soilcollembolan community were different. A redundancy analysis (RDA) showed that theinfluence of soil microbial on the soil collembolan community was the largest (p<0.01), whichwas24%, and the genetic diversity of soil collembolan was most influenced significantly bythe interaction between the soil properties and the soil microbial (p<0.01), which was38%.In summary, the impact of exogenous carbon on soil collembolan community was higherthan that of the exogenous nitrogen. Soil properties could be changed in the decompositionprocess of exogenous carbon and nitrogen, such as soil organic carbon and total nitrogen, andsoil microbial biomass could be increased under disturbances by the exogenous carbon. Soilcollembolan community structure and soil microbial community structure could be changedwith a change of soil properties, and then soil collembolan community could be furtherinfluenced by soil microbial. These conclusions have important scientific significance andprovide basic information for reinforcing soil management, increasing soil biodiversity,improving soil nutrition and creating a better soil ecological environment for plant and crop.