<正>对自日本引进的赤松（Pinus densiflora）27个抗病家系进行人工抗病性测定，结果发现抗病各家系对3个不同来源的松材线虫（Bursaphelenchus xylophilus）虫株都表现出不同程度的抗病性，且差异明显。综合3次接种试验结果发现，引进赤松中有13个家系（1、4、5、6、7、8、13、14、15、17、20、23和25号）抗病表现较好。对5号抗病家系接种松材线虫后，分别按时间进程（4、8、12、24、36、48、72、96、120h）进行茎段取样，组织病理学观察发现松材线虫在引进的抗病赤松体内的迁移速度较普通赤松慢，且松树茎内木射线细胞和树脂道泌脂细胞周围的薄壁细胞出现病变较普通赤松晚，病变程度也比普通赤松轻。

C4.5 algorithm is a classic decision-tree-based data-mining algorithm, It classifies and analyzes data based on information entropy theory. It mainly includes such following steps as pre-procession of data, creation of decision-tree, pruning of decision-tree, rules extraction from decision-tree. C4.5 algorithm is introduced in this paper, and it is applied in a data analysis on second stage investigation of forestry resources. The promising prospect of data mining in investigation and data analysis of forestry resources has been proved.