落叶松八齿小蠹在落叶松火烧木上的垂直分布

VERTCAL DISTRIBUTION OF LARCH BARK BEETLE ON BURNED TREES OF LARCH

落叶松八齿小蠹(Ips subelongatus Matsch.)是大兴安岭火烧迹地蛀干害虫的优势种之一。该虫在落叶松火烧木上、中、下三部位均可侵害,其中以胸高处(1—2m)虫口密度最大。在中、高密度情况下,侵害高度通常较树高低1.5—2.0m。虫害木最小被害树径及树皮厚度分别为5.0cm(3.5—8.0cm)和0.15cm(0.1—0.2cm)。根据调查数据分析,建立了胸高处虫口密度与平均虫口密度的回归关系式。

The larch bark beetle (Ips subelongatus Motsch.) is one of the most dominant stem-pests in burned areas of Great Xingan Mountains. The larch trunk can be attacked from the base to the top, The highest attacking density is at B. H. position of burned trees. Under mid-or high density conditions, the attacked height is about 1.5—2.0m lower than the height of trees. The average diameter and average bark thickness of the attacked trunks are 5.0 cm (3.5—8.0cm) and 0.5cm (0.1—0.2cm) respectively. According to investigating and analysing data, we have got a useful regression equation:Y=1.73+0.48X; r=0.94, Y—average,density (attacks/1000cm^2); X—density at B. H.position (attacks/1000cm^2)