Ecological stoichiometric characteristics of Carbon (C), Nitrogen (N) and Phosphorus (P) in leaf, root, stem, and soil in four wetland plants communities in Shengjin Lake, China.

Ecological stoichiometric should be incorporated into management and nutrient impacted ecosystems dynamic to understand the status of ecosystems and ecological interaction. The present study focused on ecological stoichiometric characteristics of soil, and leaves, stems, and roots of different macrophytes after the banning of seine fishing in Shengjin Lake. For C, N, and P analysis from leaves, stems, roots, and soil to explore their stoichiometric ratio and deriving environmental forces, four dominant plant communities (Vallisneria natans, Zizania latifolia, Trapa natans and Carex schmidtii) were collected. The concentration of C, N, P and C: N: P ratio in leaves, stems, roots, and soil among the plant communities varied significantly. Along the depth gradient high C: N was measured in C.schmidtii soil (7.08±1.504) but not vary significantly (P >0.05). High C: P result was found in T.natans (81.14±43.88) and in V.natans soil (81.40±42.57) respectively with no significant difference (p>0.05). Besides, N: P ratio measured high in V. natans (13.7±4.05) and showed significant variation (P<0.05). High leaf C: N and N: P ratio was measured in C. schmidtii and V. natans respectively. Nevertheless, high leaf C: P ratio was measured in Z. latifolia. From the three studied organs, leaf C: N and N: P ratio showed high values compared to root and stems. The correlation analysis result showed that at 0-10cm depth soil organic carbon (SOC) correlated negatively with stem total phosphorus (STP), and root total nitrogen (RTN) (P<0.05) but positively strongly with leaf total phosphorus (LTP) and leaf total nitrogen (LTN) (P<0.01) respectively. Soil total nitrogen (STN) at 0-10cm strongly positively correlated with leaf total phosphorus (LTP) (P<0.01) and positively with RN: P and leaf total carbon (LTC) (P<0.05). Soil basic properties such as soil moisture content (SMC), bulky density (BD) and pH positively correlated with soil ecological stoichiometric characteristics. Redundancy analysis (RDA) result showed available nitrogen (AN), soil total nitrogen (STN), and available phosphorus (AP) were the potential determinants variables on plants stoichiometric characteristics.

Temporal and spatial variations in zooplankton communities in relation to environmental factors in four floodplain lakes located in the middle reach of the Yangtze River, China.

A comparative limnological study of the zooplankton communities and their relationship with environmental factors was conducted to test the temporal and spatial changes among lake groups. In our study of four lakes, the lowest gamma (γ) diversity was recorded in January 2017, with a total of 25 zooplankton taxa. The highest γ diversity was recorded in May 2016, with a total of 55 zooplankton taxa. Species turnover in space (ß) were from 14.98 to 25.81. Markedly temporal and spatial variations were observed in the zooplankton community. The higher mean cladocera density (57.70 ind. L-1 and 39.85 ind. L-1) was observed in May and August, then decreased gradually with the lowest in January. The mean copepoda density ranged from 8.71 ind. L-1 in January 2017 to 32.04 ind. L-1 in August 2016. The mean rotifera density was significantly higher than that of the other two crustacean zooplankton (p < 0.01), within the range of 89.36-1139.2 ind. L-1. We also observed that zooplankton density exhibited significant seasonal changes from NMDS (Nonmetric multidimensional scaling analysis). Redundancy analysis revealed that environmental factors, such as water temperature and transparency, have significantly influenced the zooplankton community structure.