湖沼型血吸虫病流行区钉螺空间分布格局的样点尺寸效应

Sample unit size effects of spatial pattern of Oncomelania hupensis population in marshland schistosomiasis epidemic areas

目的探讨钉螺空间分布格局的样点尺寸效应。方法对江西省鄱阳湖区的试验样地进行"推扫式"钉螺调查,获得试验样地以0.33 m×0.33 m为基本单元大小的连续覆盖钉螺调查数据。以不同格点数目组合为不同的假想样点尺寸,运用聚集度指标、回归分析和聚集因子指数进行钉螺空间格局测定。结果钉螺种群空间格局为聚集分布,样点尺寸越小越能反映出钉螺种群的空间聚集;回归结果表明钉螺主要以个体群形式分布,且相互吸引,聚集强度与钉螺密度有关;种群聚集均数表明,钉螺的空间聚集与钉螺习性和环境因素或钉螺自身的聚集行为等有关,其中由生物习性导致的聚集行为用小样点尺寸可以得到更好的测定。结论湖沼型血吸虫病流行区钉螺空间分布格局为聚集分布,样点尺寸不同会影响到生物指标的测定结果。

Objective To explore the sample unit size effects of spatial pattern of Oncomelania hupensis population in the marshland schistosomiasis epidemic areas.Methods The push-broom method was performed to survey the snails in the study site in a basic unit size of 0.33 m×0.33 m in Poyang Lake region of Jiangxi Province.After combining different amount of survey cells,the aggregation indicators,regression models and aggregating factor index were employed to study the spatial distribution pattern.Results The snail population was in aggregation pattern and the smaller sampling unit could produce higher degrees of aggregation.The regression models showed that the snails distributed in the form of individual groups with attraction with each other and the aggregation was related with the snail density.The clustering factor index demonstrated that the aggregation was introduced by aggregating behavior habit of the snails and environmental factors,or only by snail habit itself,and the aggregating habit of snails could be expressed better by the smaller sampling unit.Conclusion The spatial pattern of O.hupensis population in the marshland schistosomiasis epidemic areas is in aggregation pattern,and the sample unit size can affect the calculation results of the related biological indices.