Research On The Space Quantitative Relationship Between Distribution Of Oncomelania Vegetation And Factors

Schistosomiasis distribution has strict locality.It is related with thegeographical distribution of snails.While snail is the only intermediate hostof schistosomiasis, in order to control and elimilate schistosomiasis,we needto study the geographical conditions of breeding schistosomiasis andsnails.Their distribution and breeding environmente is closely related tonatural factors. For example, latitude, temperature, soil temperature,elevation, water, soil and vegetation,etc. Among numerous factors the studyof micro geographical factors with the relationship of snail distribution tocontrol snail and schistosomiasis prevention has important significance.We conducted an area of50*50m area experiment in Henghumarshland at Poyang Lake, in November,2013.So we got snail distributiondata, vegetation height and vegetation cover data. The snail density spatialdistribution data was divided into three levels, numbered in0,1-20,21. Ashingcarex coverage （HhtcC）and Miscanthus coverage （WjmC）were dividedinto10grades. Ashing carex height（HhtcH）and Miscanthus height（WjmH）were divided into7grades.Analysis the weight of evidence of threelevels of Bayesian snail density and finally get multi-weights of evidenceBayesian probability three levels of snail density.According to the studying of Poyang lake marshland’s snails andvegetation coverage–height shows that: the snail density of0in every box’sweight value’s58.5%of the area is concentrated on70%of these geographyobjects, the snail density of1-20in every box’s weight value’s55%of thearea is concentrated80%on these geography objects, the snail density ofmore than21in every box’s weights value’s25%is concentrated on80%of these geography objects.The presence of snails is closely related to vegetation height and vegetation. It issuccessful to applicated the model “vegetation height-cover "geographical combination of factors to found “snail density at0per box”,"snail density at1-20per box","snail density at21or more" to found the presence of snails.Due to the scope of, experiment is small, the geographical factors mainlyrefers to ashing carex and miscanthus. It is lack of the study of therelationship betweend the other vegetation with snail distribution. The studyof vegetation coverage found that some columns of the grid coverage wassignificantly higher than the surrounding vegetation cover grid, because ofsome human factors.There are some of the vegetation coveragemeasurement bias. The method adopted by the weight of evidence of humanfactors is relatively small, and relatively objective. The geographical factor indetermining weights reduces subjectivity too. The geographical factor datafrom field surveys is calculated from first-hand data. And the disadvantage ofit is over-reliance on data.