第类，高虫口密度、高被害株率、中拥挤度。
High insect density, high attacked trees rate, middle crowded degree.
木质部中的单宁、黄酮及总酚含量与被害株率也不存在相关关系。
Tannin, phenol and flavone contents in the xylem showed no significant correlation with the damaged trees rate.
本文采用平均虫口密度、拥挤度和被害株率作为标准地的指标，对杨树蛀干害虫的危害状况作动态分析。
Dynamic analysis of poplar stem borer was done with population density, crowded level and percentage of damaged trees on sample plots.
结果表明，不同杨树品系间韧皮部单宁含量差异极显著，木质部单宁含量差异不显著；杨树各品系的单宁含量与杨树的被害株率关系不紧密。
Results showed that a significant difference in tannin content was found in phloem of different poplar strains, while the difference in xylem was not obvious.
结果表明，不同杨树品系间韧皮部单宁含量差异极显著，木质部单宁含量差异不显著；杨树各品系的单宁含量与杨树的被害株率关系不紧密。
Results showed that a significant difference in tannin content was found in phloem of different poplar strains, while the difference in xylem was not obvious.
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