Soil fauna community structure in Cryptomeria fortunei artificial stands at different slope elevations in summer

Key words: 
• soil biology /
• Cryptomeria fortunei plantations /
• slope /
• soil fauna /
• community structure

Abstract: Soil fauna, an important component of soil ecosystems, plays an important role in decomposition of biological remains, affects soil properties, and enhances material recycling and energy conversion in the soil. Understanding the impacts of slope elevation on soil fauna is essential to achieve sustainable Cryptomeria fortunei artificial stand management and biodiversity conservation; therefore, an investigation on soil fauna was carried out in Cryptomeria fortunei plantations. Three sample plots were set at three slope elevations （Plot Ⅰ-1 088 m, Plot Ⅱ-987 m, and Plot Ⅲ-830 m）. 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 transported to laboratory for detailed classification to family level. Mesofauna was collected by steel core （r = 5 cm, v =100 cm3） and store in soil fauna sealing black bags. The collected samples then were transported to laboratory within 12 h and subsequently separated by Baermann method （for nematodes） and Tullgren method （for mesofauna） over a period of 48 h, respectively. All collected soil fauna were calculated and classified by microscope, and identified to the family level following Pictorial Keys to Soil Animals of China. Analysis was conducted using the following indexes: Sorenson, Morisita-Horn, Shannon-Wiener, Pielou, Simpson, and Density-groups. Results showed a total of 94 soil fauna orders belonging to 5 phyla and 13 classes with an average density of 3.46 104 individualsm-2. The density and number of groups in Plot Ⅲ at lower elevation are significant higher than that in the rest of two plots （P＜0.05）, and there is no significant difference between the Plots Ⅰ and Ⅱ （P＞0.05）. Compared to Plots Ⅰ and Ⅱ, the soil fauna density in litter layer and 10~15 cm soil layer of Plot Ⅲ is significantly higher than that in Plots Ⅰ and Ⅱ （P＜0.05）. The vertical study showed that more than 43% of the individuals was found in the 0-5 cm layer and more than 72% of the group number was found in the litter layer in each plot. Plot Ⅲ had the highest soil fauna density for Phylum Nematoda, and Classes Insecta, Arachnida, and Diplura. The Sorenson and Morisita-Horn indexes showed that slope elevation had a stronger effect on soil fauna density than soil fauna group type. Also, the highest Shannon-Wiener, Pielou, and Density-groups indexes were found in Plot Ⅲ at the lower elevation. Thus, slope elevation affected distribution and diversity of soil fauna in Cryptomeria fortunei plantations, and to reserve litter layer is the key to keep the soil fauna diversity. ［Ch, 3 fig. 5 tab. 20 ref.］