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采用生物种群空间分布型测定方法,对池州沿江低丘的钉螺空间分布型进行了研究。结果表明:(1)钉螺平均密度为每0.11m2 0.77只,密度分布规律为河滩﹥沟渠﹥水田﹥荒地﹥旱地﹥滩地杨树林地,河滩与其他5种土地利用类型的钉螺密度间存在极显著差异;另外,钉螺分布的变异系数(CV)大小规律为滩地杨树林地﹥旱地﹥荒地﹥水田﹥沟渠﹥河滩。(2)滩地杨树林地、河滩、荒地和沟渠中的钉螺空间分布型为聚集分布,旱地和水田则分别为均匀分布和随机分布,而钉螺在整个研究区域呈聚集分布中的负二项分布,其公共K值为2.1964。(3)钉螺聚集的原因主要是由于某些环境因素所引起,且个体间相互排斥,密度(m)为每0.11 m2 2.8505只可以作为判别钉螺聚集原因的临界值。(4)建立了允许误差分别为0.1、0.2及0.3时的Iwao理论抽样数模型和估计种群密度的零频率模型。
Based on the spatial distribution of biological populations, the spatial distribution patterns of Oncomelania snails in the low hills of Chizhou were studied. The results showed that: (1) The average density of Oncomelania snails was 0.77 per 0.11 m2, and the density distribution of the snail density was river beach> ditch> paddy field> wasteland> dry land> poplar woodland, beaches and other five land use types, In addition, the variation of coefficient of variation (CV) of Oncomelania snail distributed in poplar forest land> dry land> wasteland> paddy field> ditch> river beach. (2) The spatial distribution patterns of Oncomelania snails on poplar woodlands, floodplains, wasteland and ditches of beachland are aggregated distribution, dryland and paddy field are evenly distributed and randomly distributed, while Oncomelania snails distribute negative binomial distribution in the whole study area , Its public K value is 2.1964. (3) The reason for the aggregation of Oncomelania snails is mainly caused by some environmental factors and the mutual exclusion of individuals. The density (m) is 2.8505 per 0.11 m2, which can be used as the critical value for judging the causes of snail aggregation. (4) The Iwao theoretical sampling number model and the zero-frequency model for estimating the population density with the allowable errors of 0.1, 0.2 and 0.3 respectively are established.