洞庭湖区钉螺空间格局的动态分析

目的探索洞庭湖区湖北钉螺空间格局的动态变化,为钉螺生态学及螺口动力学研究提供基础信息。方法选择湖南省岳阳市君山区洞庭湖的一块草滩为现场,在2007年10月～2008年5月洞庭湖未涨水期间进行系统抽样查螺;分框计数,压螺鉴定死活。对部分汇总数据进行对数转换,计算扩散系数C、众生指标I、平均拥挤度M^＊、La指标等聚集度指标;拟合Taylor模型LgS^2-Lgm,Iwao模型M^＊-m、兰星平的La-m模型,C-S2模型等对空间格局的分布进行检验。结果不不同时间点扩散系数C、众生指数I、平均拥挤度M^＊、La指标都有统计学意义,取值与界限值相比均使得S2-M〉0及S2/M〉1;Taylor对数线性模型,M＊-m、La-m、C-S2等线性模型均有统计学意义,参数取值组合也均使得S2-M〉0及S2/M〉1;聚集度指标随均值同方向变化。结论钉螺空间分布格局动态成聚集分布,聚集度指标随均值同方向变化。

Analysis of dynamic spatial pattern of the Oncomelania hupensis in Dongting Lake District Wang

Objective To understand dynamic change of spatial pattern of Oncomelania hupensis in Dongting Lake district so as to provide information for research on Oncomelania hupensis ecology and popu- lation dynamic. Methods A marshland close to Junshan Park in Yueyang City Hunan Province was selected as the pilot. O. hupensis snails were investigated by systematic sampling method in the water withdrawal period between October 2007 and may 2008, and the number of the snails were surveyed and the survival status were identified by dissection method. Part of the data was transferred with logarithm method, aggregation indices such as C,I,M^＊,La,etc and regression models such as Taylor＇s LgS^2-Lgm,Iwao＇s M^＊-m,Lan xing- ping＇s La-m,C-S2 etc were analyzed to examine the type of spatial pattern in different time. Results The aggregation indices such as C, I, M^＊, La are all significant and make the expression S2-M〉0 and S^2/M〉I true by comparing them with according criteria; Taylor model,lwao model,La-m model ,C-S^2 model are all significant and the goodness-of-fit is reasonable, which also make the expression S^2-M〉0 and S^2/M〉I true by comparing the parameter estimate with according criteria; the aggregation indices change with the mean in the same direction. Conclusion The spatial pattern in different time is aggregation distribution basically; the aggregation indices go the same way with the mean density.