Spatial chaos of metapopulation incurred by Allee effect,overcrowding effect and predation effect Effects of crowding signals on population growth of two Brachionus rotifer species Multi-scale analysis of landscape characteristics in coastal wetlands in Yancheng, Jiangsu, based on the weighted Ripley‘s K-function method Effect of Straw Returning and Reduced Tillage on Interspecific Competition and Complementation in Wheat/Maize Intercropping System