The oil shale dump in Maoming, Guangdong, has been a great social problem on environmental pollution and destruction so that great attention has been paid to its ecological restoration and reconstruction. The objective of this study was to investigate the species composition of soil fauna and its diversity in oil shale dump after the application of different ecological restoration approaches in the past in order to understand the biological effect of different ecological restoration approaches. Three plots were set on oil shale dump near Maoming city: “North plot" was a newlyplanted mixed young forest with various tree species, “south plot" was a 20-year-old Acacia auriculaeformis forest, and the “control plot" was a 20-year-old naturally-recovering grassland. Soil animals, mainly including macro-meso groups, were collected by methods of hand-sorting and Tullgren funnel extraction and were identified into family or genus level, with only a small portion into order (e.g. Chllopoda) level or into species (e.g. Isopoda) level. The total number of samples obtained in the present study was 11,164 individuals, which belonged to 27 orders and 110 families or genera. Shannon index (H′), DGs (based on species) and DGg (based on groups) were used to analyze the diversity difference of soil animals between different plots. The major results were:
(1)North plot: 33 families or genera belonging to 9 orders were found in this plot. The main Group was Caritermes, accounting for 63.4% of total; next was Tetramorrium, 21.3%; Hymenoptera, mainly Formicidae, has more genera than others, accounting for 80% of the whole genera in this group. Diversity of soil animal in this plot was very low because that H′ index was only 1.2 and the DGs index and DGg index were 4.0 and 1.3, respectively.
(2)South plot: 61 families or genera belonging to 23 orders found in this plot; and Malmcoangelia and Tetramorium were the main groups, accounting for 60.3% and 10.2%, respectively. Two genera of Annelda and two genera of Isopoda, only accounted for 2.6% and 1.9%, but they were considered to be major groups due to their large body sizes and distinct habitat characteristics. Acarina has more number of individuals and families or genera, with its individual number accounting for 67.5% of the total; and the number of families or genera of this group accounting for 70% in this plot. The diversity indexes (H′, DGs and DGg) in this plot were significantly higher than those in north plot, they were 1.65, 16.7 and 7.75, respectively.
(3)Control plot: 67 families or genera of soil animals belonged to 23 orders. The main Groups were Tetramorium、Lasius、Bothriomymex of Formicidae and Malmcoangelia of oribatid mites which accounted for 20.0%, 17.1%, 13.8% and 14.5%, respectively. Formicidae of Hymenoptera was the group with the maximum number of individuals, accounted for 51.0%; and Diplopoda was the group with the most families or genera. The H′ index and DGs index, being 2.54 and 17.7, were higher than those in south plot, while DGg index with 7.20 was lower that that in south plot.
Results showed that the species composition and diversity indexes were higher in “south plot" than those in “north plot" and “control plot", which demonstrated that using Acacia auriculaeformis forest to restore the oil shale dump was an effective approach in terms of soil biodiversity.