A STUDY ON THE EFFECT OF THE SHELTER-FOREST COMMUNITY ON THE OF SANDS OF THE MIDDLE AND LOWER REACHES OF YANGTZE RIVER ON THE DISTRIBUTION OF ONUCOMELANIA HUPENSIS

The Schistosomiasis has special harm to health.Oncomelannia hupensis is the only intermediate host of Schistosome,and the weakest link in the life cycle of Schistosome.Killing Oncomelannia hupensis can properly control Schistosomiasis,protect wetland and water resource.There are four Shelter-forest communities on the sands of the middle and lower reaches of the Yangtze River:the Pterocarya stenoptera community,the Populus canadensis community,the Salix mastsudana community and the Phragmites commuis community.Taking five sample plots(20m?0m) in every forest,and setting five quadrats(1m?m) in every sample plot,calculating the species of plants in the bottom of the forest and coverage,measuring sunlight and soil humidity in every sample plot.At the same time,setting a sample lattice with the size of one square foot(0.11m2) in every quadrat randomly,so as to investigate the number of Oncomelania in the earth surface and calculate its death rate.By investigation and statistics,the result showed that:(1) The reliable scope of disparity in the density(single/0.11m2) of Oncomelania among the Pterocarya stenoptera community and the Populus canadensis community,the Salix mastsudana community,the Phragmites commuis community on the beaches of the Yangtze River was 8.2809-18.2390,-0.7622-1.6462 and 5.3190-13.3809,respectively;(2) There were 9 species familiar plants under the Pterocarya stenoptera community,and Leonurus artemisia,Humlus scandens,Perilla frutescens,Nerium indicum,Artemisia selengensis were representing negative correlationship and with allelopathy on the Oncomelannia hupensis,and Phalaris arundinacea,Oenanthe javanica,Paederia scandens,Equisetum hiemole were taking on positive correlationship;(3) The range of the most suitable to live in for Oncomelania was that the insolation was 5?00-15?00lx,the soil moisture was 20%-40% and the vegetation cover under the forest was 40%-70% between the ecological factors of the Pterocarya stenoptera community and Oncomelania;(4) The experiments indoor disclosed that the effect of killing-Oncomelania of 0.5% water-living leaves was 84%,which was superior to the same density water-dad leaves of 42.7%.The result in research before may be provided as reference basis in order to improve the structure of community and to raise the effect of killing-Oncomelania of the pterocarya stenoptera community.At present,the plant ecology research of extinguishing O.hupensis is a hotspot in the international research of extinguishing O.hupensis.Our present work just focuses on this aspect.But only the laboratory work is by far insufficient,we need carry out more investigations in the open air and more researches of increasing and decreasing rule of O.hupensis and its mechanisms in artificial phytocenosis against O.hupensis.Only from carefully binding these two ways,can we truly implement them and benefit the humanity.