Fifty-three plots of 20 m×30 m were set up according to stand type and site condition of Betula alnoides in Mountain Daqingshan, Guangxi, and stand structure and site properties were investigated as well as attack of Arbela spp.to reveal status of attack by the pest and the key influencing factors .Partial correlation analysis showed that stand type ( r=-0.361, P=0.008), cover (r=-0.330, P=0.016) and height (r=-0.471, P=0) of understory vegetation, and slope position (r=-0.404, P=0.003) were significantly correlated with the ratio of pest-damaged individuals , these were key factors influen-cing attack of Arbela spp.in B.alnoides plantations .By the variance analysis , the pure plantations and mixed ones with Castanopsis hystrix were attacked the most heavily with the ratios of damaged individuals of 49.35%and 43.55%, respec-tively, obviously higher than those in mixed plantations with Cunninghamia lanceolata ( 17.63%) or Manglietia glauca (14.04%).The plantations with thicker understory vegetation were damaged more slightly .The pest attack on lower slopes was high up to 68%, remarkably higher than that on upper and middle slopes , which was perhaps due to the fact that plan-tations on lower slope were closer to source of the pest .%以广西大青山西南桦（ Betula alnoides）人工林为研究对象，依据林分类型、立地状况设置53块20 m×30 m的典型样地，调查了其立地和林分特征以及拟木蠹蛾（ Arbela spp．）为害状况，揭示了西南桦人工林拟木蠹蛾为害的关键影响因子。偏相关分析表明：林分类型（r＝－0．361，P＝0．008）、林下植被盖度（r＝－0．330，P＝0．016）和高度（r＝－0．471，P＝0）以及坡位（r＝－0．404，P＝0．003）与西南桦林分感虫株率相关显著，是影响西南桦林分拟木蠹蛾为害的关键因子。方差分析显示：西南桦纯林和西南桦×红锥（ Castanopsis hystrix）混交林拟木蠹蛾为害最为严重，其感虫株率分别为49．35％和43．55％，显著高于西南桦×杉木（ Cunninghamia lanceolata）（17．63％）和西南桦×灰木莲（Manglietia glauca）混交林（14．04％）；林下植被茂盛的林分内拟木蠹蛾为害程度较轻；下坡林分感虫株率高达68％，显著高于上坡和中坡（20％以下），可能与下坡林地更靠近虫源有关。
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