Diversity Characteristics Of Soil Macrofauna Community In The Disaster Area Of Iron Tailings Dam Failure In Xiangfen

Soil macrofauna have unique functions and roles in soil organic matter decomposition and nutrient cycling.They also can be used as an important indicator of soil health and environment changes in mining areas.In order to explore the structure and diversity of soil macrofauna community during the recovery process of the dam break area,this paper selects the zone affected by the tail collapse in Xiangfen as the study area.The research method was combined with field survey sampling and indoor sample identification analysis.In July 2017,eight habitats were selected for macro-soil fauna research,including dam-breaking areas（three habitats）,natural abandoned land（two habitats）,and control areas（three habitats）.Analysis of the differences in the structure of soil macrofauna community,as well as the diversity index of soil macrofauna,and relationship between soil macrofauna and soil properties.The results of this paper are as follows:（1）Among the eight habitats,50 groups and 568 individuals were obtained,belonging to 4 phyla,9 classes,23 orders and 47 families.Among them,the average density of soil fauna in the dam-breaking areas,natural abandoned land,and control areas were 108.44 ind·m^-2,309.33 ind·m^-2,190.22 ind·m^-2,and the number of groups was 23,40,29,respectively.The average density and the groups in the natural abandoned land were highest,and the lowest in the dam-breaking area.On the whole,formicidae,mycetophilidae,miridae,carabidae,Oonopidae are widely distributed in all habitats and are the main groups of research.（2）The horizontal distribution of different habitats shows that the densities and groups in habitat 5 are the largest,and the densities of habitat 3 and the groups in habitat 1 are the least.Analysis of variance showed that there were significant differences in the densities and groups of soil fauna in eight habitats.There were significant differences in the groups among dam-breaking areas,natural abandoned land,and control areas.There was a significant difference in the densities between dam-breaking areas and natural abandoned land,but there was no significant difference in the densities when control areas is compared with the dam-breaking areas and the natural abandoned land.（3）The densities and groups of soil fauna are basically 0-10cm larger than10-20cm,and they have the characteristics of surface aggregation.Among them,surface aggregation of the natural abandoned land is more pronounced than dam-breaing areas and control areas.Similarity results show that the Sorenson coefficients of different habitats are mostly between 0.25 and 0.5,and they are not similar in medium.The Morisita-Horn coefficient of each habitat fluctuates more than the Sorenson coefficient,indicating that the ecological groups have different ecological functions in different habitats.（4）The diversity analysis showed that the shannon-wiener index,pielou index and margalef index of the control areas are all higher,the corresponding densities of soil fauna is higher,and the stability of the soil fauna community is higher.Natural abandoned land have higher shannon-wiener index,lower pielou index and higtest margalef index,and the corresponding soil fauna have the highest density,but the stability of the soil fauna community is poor.Shannon-wiener index,pielou index and margalef index of the dam-breaking areas are all low,the corresponding density of soil fauna is also low,and the stability of the soil fauna community is worst.The shannon-wiener index,pielou index and margalef index of the control area are mostly higher than that the zone affected by the tail collapse,while the shannon-wiener index and margalef index of the natural abandoned land are higher than those in the dam-breaking area.（5）There was a significant positive correlation between the groups of soil macrofauna and total potassium（p<0.05）,and the correlation between the groups and densities of soil fauna and the other physical and chemical properties were not significant（p>0.05）.Soil water content was significantly positively correlated with soil fauna shannon-wiener index and negatively correlated with soil fauna simpson index（p<0.05）.There was a significant positive correlation between soil available potassium and soil fauna pielou index（p<0.05）.There was a significant positive correlation between soil total potassium and soil fauna margalef index（p<0.05）.There was a significant positive correlation between soil total nitrogen and soil fauna shannon-wiener index and margalef index（p<0.05）.There was no significant correlation between other soil properties and diversity index（p>0.05）.The diversity of soil fauna community in the area affected by the iron tailings dam failure is obviously different from that in the control area,and the quantity structure of the soil fauna community in the natural abandoned land is better than that dam-breaking areas.It shows that the natural recovery is more conducive to the development of soil fauna communities after the environment is disturbed.Therefore,the soil fauna community in the ecosystem restoration of the area affected by the iron tailings dam failure also has its own unique features,which are different from other mining areas.