Turkish Journal of Zoology Turk J Zool (2019) 43: 379-387 http://journals.tubitak.gov.tr/zoology/ © TÜBİTAK Research Article doi:10.3906/zoo-1812-9 Structural characteristics of the soil fauna community in beach wetlands of the Poyang Lake region 1 1 1 2 3, 1 4 Ping LU , Nianhua DAI , Guohua ZHANG , Meiwen ZHANG , Derong XU *, Zhuorong LIU , Zhiqiang HUANG 1 Institute of Biological Resources, Jiangxi Academy of Sciences, Nanchang, P.R. China 2 Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, P.R. China 3 Institute of Translational Medicine, Nanchang University, Nanchang, P.R. China 4 Jiangxi Provincial Management Bureau of Wild Fauna and Flora Conservation, Nanchang, P.R. China Received: 04.12.2018 Accepted/Published Online: 30.05.2019 Final Version: 01.07.2019 Abstract: We examined the soil fauna community composition and structure of Poyang Lake beach wetlands using the modified Tullgren and Baermann methods during September and December 2015. A total of 3755 individuals were obtained from 2 samplings, which were found to belong to 7 classes, 8 orders, 3 suborders, and 17 families. Among these, the Oribatida, Prostigmata, Nematoda, and Onychiuridae were dominant. The functional groups of soil animals included omnivores, saprozoics, predators, and phytophages. Analysis results of the soil fauna composition and diversity showed that the soil animals were mainly concentrated at the 0–10 cm depth, presenting as a significant surface convergence phenomenon. The numbers of individual soil animals differed significantly between sampling sites (P < 0.05), with the beach wetland in Lianhu Township having the highest numbers of individuals and groups. The effect of water level variability on numbers of soil animals was not significant (P > 0.05). Habitat type and sampling time both had highly significant effects on diversity and evenness (P < 0.01), and significant effects on species richness (P < 0.05). During water level changes in Poyang Lake, the individual number, group number, and diversity of the soil animals were closely linked to the sampling site. These results provide basic data for further studies on soil fauna ecology in Poyang Lake beach wetlands. Key words: Community structure, distribution pattern, functional group, Poyang Lake region 1. Introduction processes of degradation and restoration (Liu et al., 2014), Wetland ecosystems have characteristics of both terrestrial acting as indicators for the maintenance of biodiversity and aquatic ecosystems. Their complex structure enables and ecological balance (Zhang et al., 2013; Chen et al., them to provide a variety of habitats for the growth of 2014). animals and plants (Keddy, 2010). Poyang Lake is the Previously, research on the Poyang Lake wetlands largest river-linking lake in the Yangtze River Basin and focused mostly on vegetation (Wang et al., 2014; Feng et the largest freshwater lake in China (Wang et al., 2016). al., 2016) and birds (Wu et al., 2014; Yang et al., 2016); As an important freshwater resource pool in China, it is there are only a few reports on soil fauna. The objectives of an ecological conservation library of global significance this study were to investigate the composition, abundance, (Hui et al., 2008). The Poyang Lake wetlands change with distribution, and diversity of soil fauna in typical wetlands seasonal variations in flood levels, and various types of of Poyang Lake; to analyze the structure and diversity habitats form during the process (Liu et al., 2011). These of various habitats; and to provide basic data for soil have developed a variety of wetland soils with abundant biodiversity for further studies in the lake. biodiversity (Liu et al., 2011; Wu et al., 2012; Zhang et al., 2012; Liang et al., 2015; Yang et al., 2015). 2. Materials and methods Soil animals are an important component of wetland 2.1. Overview of the research area ecosystems and are a food source for migratory birds (Wu Poyang Lake is China’s largest freshwater lake, located in et al., 2009). They also participate in the material cycles northern Jiangxi province on the south bank of the middle of wetland ecosystems (Keddy, 2010). Their dynamics and lower Yangtze River (28°24′N to 29°46′N, 115°49′E to can reflect changes in ecological functions during the 116°46′E) in a classic subtropical monsoon climate zone. * Correspondence: [email protected] 379 This work is licensed under a Creative Commons Attribution 4.0 International License. LU et al. / Turk J Zool Poyang Lake varies in size dramatically with seasonal water suspension (1:2.5 v:v) was measured with a digital rainfall: during the summer April–September wet season, pH meter, and soil organic carbon (SOC) content was its largest river-linking surface area is 4078 km2, while in determined via dichromate oxidation. Additionally, the the winter dry season from October to March, the average total N (TN) content was measured with an ultraviolet surface area is 1290 km2 (Shao et al., 2014). Hot, humid, spectrophotometer following Kjeldahl digestion (Liu at al., southerly winds prevail during summer and dry, cold, 1996). northerly winds prevail in winter. The average annual 2.4. Data analysis temperature is 17.6 °C, ranging from a mean of 5.1 °C in Group number level is expressed as the relative abundance January to 29.5 °C in July. About 1450–1550 mm of rain of soil animal groups (Lu et al., 2013). A group whose falls annually, mostly between April and June (Dong et number of individual animals accounted for more than al., 2014). During winter, the water subsides and beaches 10% of the total catch was defined as a dominant group, emerge, forming a large number of shallow depressions those accounting for 1%–10% were defined as common 2 and strands. This area of 2698 km accounts for 82% of groups, those consisting of 0.1%–1% were defined as rare the total normal water level area of the lake (Wang et al., groups, and those below 0.1% of the total were defined 2011; Dong et al., 2014); it is an important habitat for as very rare groups. Here, we classified dominant and global winter migratory birds and plays a critical role in common groups as the main groups and rare and very rare maintaining biodiversity (Zhao et al., 2007). groups as other groups. In this study, we selected beaches with the same For community diversity, we used the Shannon–Wiener elevation and habitat but different soil properties at diversity index (H’), Pielou index (Js), and Margalef index Poyang Lake and the grass shoals located at the Henghu (D) (Ma, 1994) as follows: Reclamation Farm in the Xinjian district of Nanchang city in Jiangxi province (HH); Jiangxi Poyang Lake Nanji (1) Wetland National Natural Reserve in Nanji township (NJ); Js = H′/LnS (2) and Lianhu township in Shangrao city in Jiangxi province D = (S - 1)/Ln(S) (3) (LH) (Figure 1; Tables 1 and 2). The three beach sites have where Pi is the ratio of the number of individuals to the similar flood regimes. The soil types are all meadow soil. total number of individuals in the community for the The main dominant plants in the beaches are sedges (Carex number of i species, S is the number of groups, and N is spp.), reeds (Phragmites australis), and triarrhena grass the number of individuals observed. (Triarrhena lutarioriparia). The beaches were flooded in The differences in soil fauna between different wetland summer, but in winter the waters subsided and the beaches communities were analyzed using one-way ANOVA, and were exposed. Soil fauna surveys were conducted during each taxon was analyzed separately. Tukey’s LSD test was the dry season in September and December 2015, when used to compare the significance of differences between the corresponding lake water levels at Xingzi were 13.73 m soil fauna and groups of different wetland communities. and 13.07 m, respectively. All statistical analyses were conducted using Excel 2010, 2.2. Soil fauna sampling and identification SPPSS 19.0, and CANOCA 4.5 software. Fixed sampling plots of 20 × 20 m were marked on the lake beaches or shoals, with three sampling quadrats evenly 3. Results distributed within each sampling plot. Two depth layers 3.1. Composition and characteristics of soil animals in were defined in each quadrat as 0–10 cm and 10–20 cm. Poyang Lake beach wetlands In the first quadrat of 20 × 20 cm, fauna was removed During the study period, 3755 soil animals including manually. In the second quadrat of 10 × 10 cm, fauna was 1 unidentifiable specimen were collected, belonging to removed using a modified Tullgren approach. In the third 7 classes, 8 orders, 3 suborders, and 17 families (Table quadrat of 10 × 10 cm, a 100-mL foil sampler was used 3). A total of 24 species of soil fauna were identified in to remove fauna as per Baermann’s method. Collected soil the Poyang Lake beach wetlands, among which the 4 animals were stored in 70%–75% ethanol. dominant types belonged to the order Oribatida, the Soil animal specimens were all identified to family level suborder Prostigmata, the phylum Nematoda, and the except for members of Nematoda, Araneida, and Acarina family Onychiuridae. Together, these accounted for (Yin, 1998). Functional groups were categorized based on 90.74% of the total individuals. A common group was the their feeding habits and their roles in food decomposition order Mesostigmata, accounting for 6.15% of individuals. (Xu et al., 2013). Rare and very rare species accounted for 3.11% of the total 2.3. Soil property analysis number. Soil moisture was determined by oven-drying fresh The four functional groupings of soil animals included soil at 105 °C to a constant weight.