Community structure of soil fauna in kiwifruit plantation at different slope locations

Soil fauna is an important component of soil ecosystems, which plays a significant role in the decomposition of biological remains, soil properties and the enhancement of material recycling and energy conversion in soils. Slope locations are one of the important topographical factors in mountain environments, which play an important role in driving the reallocation of water and light, and have a significant effecton plant growth, soil moisture, microbes as well as soil fauna. However, how do the slope locations affect soil fauna community is still unknown. Hence, this study focuses on the effects of slope location on the community structure of soil fauna in kiwifruit (Actinidia chinensis) plantation which was planted with the density of 2 500 indiv./hm2 in 2000.Soil fauna at three different slope locations (upper slope, middle slope and lower slope) with four soil layers (herb, 0 5 cm, 5 10 cm and 10 15 cm) in the kiwifruit plantation were studied. Macrofauna samples (n=3) were picked up by hand in each sampled slope with the area of 50 cm×50 cm (0.25 m2). After recording the types of soil fauna, the samples were put into a container with alcohol and were transported to laboratory for detailed classification to family level. Mesofauna samples were collected by steel core (r=5 cm, v=100 cm3) and were stored in soil fauna sealing black bags, then, the collected samples were transported to laboratory within 12 h and were subsequently separated by Tullgren (n=3) and Baermann (n=3) methods over a period of 48 h, respectively. Microscopy for mesofauna was with an interval of 4 h in order to prevent autolysis of Enchytraeidae, then was prolonged. All collected soil faunae were calculated and classified by microscope, and were identified to the order level following Pictorial Keys to Soil Animals of China.The results showed that a total of 2 077 individuals of soil fauna, belonging to five phyla, 13 classes and 29 orders, were collected. The highest density of total species was in upper slope and lowest density was in lower slope. The dominant communities in upper slope were Nematoda and Enchytraeidae, accounting for 22.1% and 56.3% of the individuals, respectively. Acarina, Nematoda and Enchytraeidae were the dominant groups in middle slope, accounting for 12.2%, 14.2% and 58.8% of the individuals, respectively. Collembola, Acarina and Nematoda were the dominant groups in lower slope, accounting for 23.7%, 18.6% and 35.5% of the individuals, respectively. The order of soil fauna density profile distribution was upper > middle > lower, except 5 10 cm layer. The densities of soil fauna in herb and 0 5 cm layer collected by Tullgren method were significantly higher in upper slope than in middle and lower slope (P<0.05), and the densities of soil fauna in 5 10 cm and 10 15 cm layer collected by Baermann method were significantly higher in upper slope than in middle and lower slope (P<0.05). Omnivorous soil fauna had the largest individual number compared with other guild compositions, and the total ratios of omnivorous and saprozoic soil faunae in upper slope, middle slope and lower slope were 68.72%, 76.81% and 81.1%, respectively. Shannon-Wiener index and Pielou index were higher in lower slope than in upper and middle slopes, but Simpson index was lower in lower slope than in upper and middle slopes.In sum, the guild compositions, densities of profile distribution, group numbers and diversity indexes of soil fauna in the kiwifruit plantation have significant responses to slope locations with the highest soil temperature in upper slope and soil water content in lower slope.