<正>参照国际上有害生物风险性分析（PestRiskAnalysis，简称PRA）方法，从有害生物的国内分布、潜在的经济和生态环境危害性、定殖与扩散的可能性、风险管理难度以及毛竹的经济、生态、社会重要性等几个方面进行定性和定量分析，对毛竹枯梢病病原菌竹喙球菌的风险性作了综合评价。结果表明，竹喙球菌是接近于高度危险的林业有害生物，对我国竹林资源与竹业发展具有潜在的严重。威胁，应加强风险性管理力度。

Genetic variations on traeheid microfibril angle of 55 Chinese fir clones were investigated. The results revealed that microfibri[ angle had a highly significant difference among clones. The broad sense heritability estimates of clones varied between 0. 734 and 0. 867,indicating the microfibril angle was under strong genetic control. The average genetic gains were 19. 51% for the microfihril angle if 10% of the best clones was selected. The microfibril angle decreased with increase of growth ring age and the microfibril angle at the 10th ring was about 32. 1% less than that at the 1St ring. The microfibril angle showed a highly significant difference among different rings. The correlations coefficients of microfibril angle between different tree ages since 3rd growth ring were very significant indicating that early selection for the microfibril angle would be efficient.