Composition and structure of soil fauna communities and their relationships with environmental factors in copper mine waste rock after re-vegetation

The re-vegetation of acid mine waste rock from the Dexing copper (Cu) mine in Shuilong mountain has been conducted for more than 10 years. However, few studies have assessed the composition of soil fauna communities in this restored ecosystem. Here, we investigated the relationship between the soil fauna communities and soil environmental factors in this area using two re-vegetation restoration types (shrub-dominated and herb-dominated vegetation types) and in one area without re-vegetation (control) and modified Tullgren and Baermann methods. The 3558 soil fauna individuals collected belonged to five classes, 13 orders, three suborders, and 29 families. The number of individuals and taxa of small- and medium-sized soil fauna were significantly influenced by the different re-vegetation types (P < 0.05). Soil temperature, organic carbon, total nitrogen, carbon-nitrogen ratio, total phosphorus, available phosphorus, as well as the number of individuals and taxa of soil fauna were higher in the shrub-dominated re-vegetated plots than in the herb-dominated re-vegetated plots. The number of taxa was significantly and positively correlated with soil available phosphorus (P < 0.05), and the number of taxa, diversity, and richness of the soil fauna were significantly and positively correlated with the content of cadmium (Cd) in the soil (P < 0.05). Redundancy analysis revealed that the effects exerted by soil temperature, total nitrogen, and carbon-nitrogen ratio on the main taxa of soil fauna were the most important (P < 0.05). Among the various heavy metals in the soil, Cd, lead, zinc, and Cu exerted the most significant effects on the main soil fauna taxa (P < 0.05). Our results showed that the re-vegetation types significantly influenced the community composition and diversity of soil fauna in the waste rock dump of the Dexing Cu mine in Shuilong mountain, and that soil properties and soil heavy metal content influenced soil fauna community structure.