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落叶松球蚜(Adelges laricis Uall)是辽宁省落叶松林中的一种主要害虫。为了做好防虫预报,1987年5月,我们对落叶松球蚜的若虫进行了空间分布型和抽样技术的初步研究。现将研究结果报道如下。1 材料与方法在辽宁省清原县大孤家林场落叶松种子园内,选择4块标准地,每块标准地中的落叶松不少于100株。在每株树的中下部,分东、南、西、北4个方向各选取50厘米长的标准枝,调查其上的落叶松球蚜若虫数,同时记载该树的位置(行、株)。然后按50厘米枝长为基本样方单位,列出频次分布表,用聚集度指标判断其是随机分布还是聚集分布。若是聚集分布,再用聚集分布的几种理论频数公式进行拟合,决定其属于哪种聚集分布。然后再用种群群集均数判断聚集原因。最后根据林木定置图,在每块标准地上进行各种抽样方法的比较分析,确定最适抽样方法和合适的抽样数量。
Adelges laricis Uall is a major pest in the larch forest in Liaoning Province. In order to do a good job of pest forecasting, in May 1987, we conducted a preliminary study on the spatial distribution and sampling techniques of the larch aphid nymphs. The research results are reported below. 1 Materials and Methods In Larch Garden, Daguerjia Forestry Center, Qingyuan County, Liaoning Province, 4 standard plots of no less than 100 larch in each standard were selected. In the middle and lower part of each tree, select the standard branch of 50 cm in the east, south, west and north directions, and check the number of larch aphid nymphs, and record the location of the tree (row, strain) . Then according to 50 cm branch length as the basic sample unit, lists the frequency distribution table, with the degree of aggregation index to determine whether it is random distribution or aggregation distribution. If the aggregate distribution, and then aggregate distribution of several theoretical formula to fit the frequency, to determine their belonging to what kind of aggregation distribution. Then use the average number of clusters to determine the aggregation reason. Finally, according to the forest plan, comparative analysis of various sampling methods is carried out on each standard ground to determine the optimum sampling method and the appropriate number of samples.