SPATIAL PATTERN OF SEMISULCOSPIRA LIBERTINA POPULATION IN SMALL WATERSHED IN WESTERN ZHEJIANG

Semisulcospira libertina is a dominant superior species of snails dwelling in the reservoir basin in mountains in western Zhejiang. Specimens were qualitatively collected from 9 sampling sites in different environmental conditions, and they were calculated and analyzed by Taylors Power Law, Iwao's Patch Regression and Morisition Index, respectively. The result showed that the difference of S. libertina population densities was quite significant in river basin. The spatial layout of population theoretically belonged to clumpy and negative binomial distribution, which was mainly caused by environmental pollution and features of the river basin' s bed. Fig 2 , Tab 3 , Ref 10