中文摘要：

以黑龙江省哈尔滨市林业局丹清河林场的针叶林、阔叶林及针阔混交林3种天然次生林为对象，以无干扰模式为对照，研究粗放经营模式和目标树经营模式对植物群落结构及其多样性的影响。结果表明：1）在针叶林、阔叶林、针阔混交林中，相对于粗放经营模式和无干扰模式而言，目标树经营模式中以目标树为主的第1林层断面积值最大，占林分断面积百分比为95．00％，90．00％，87．00％，但第2，3林层断面积最小，形成了合理的林冠结构；2）目标树经营模式的林木平均密度（408—858株·hm-2）显著低于（P〈0．05）粗放经营模式（992～1917株·hm-2），而平均胸高断面积（18．18～46．03m2·hm-2）与粗放经营模式（18．43—39．70m2·hm-2）无显著差异（P（0．05），平均树高（11．8～14．9m）和平均胸径（15．94～27．34cm）均显著高于（P〈0．05）粗放经营模式（分别为7．1～11．0rll和10．18～19．00cm）；3）粗放经营模式和无干扰模式60％以上的林木为小径木（12em以下），目标树经营模式60％以上为中径木（14—18cm）和大径木（20cm以上）；4）粗放经营模式乔木层的多样性高于目标树经营模式；灌木层除阔叶林的多样性与目标树经营模式不可比外，其余林分的多样性均高于目标树经营模式；草本层的多样性则以目标树经营模式为最高；5）粗放经营模式只注重短期经济价值而忽略生态要求，无干扰模式只注重绝对生态保护而忽略人对森林资源的利用需求，二者都不符合人类经营森林的目标。目标树经营模式可改善群落和林冠结构，不仅能够获得较好的经济效益，还能平衡生态功能，符合人类经营森林的目标。

英文摘要：

We studied the different effects of extensive forest management regime and target tree management regime on plant community structure and biodiversity of natural secondary coniferous forest, broad-leaved forest and mixed forest in Danqinghe Forestry Farm which locates in Harbin, Heilongjiang Province, no disturbance forest stand was selected as reference. The results showed that： 1） Compared with extensive forest management regime and no disturbance, the basal area of the first canopy layer under target tree management regime was the highest, proportion of basal area was 95.00% , 90. 00% , 87.00% in coniferous forest, broad-leaved forest and mixed forest respectively. The basal area of the second and third canopy layer under target tree management regime was the lowest. All of these implied that stand under target tree management regime have the best canopy structure. 2） The average stand density under target tree management regime（408 -858 tree· hm-2） was significantly lower than that under extensive forest management regime（992 -1 917 tree·hm-2） （p 〈 O. 05 ）, there was no difference in average basal area. Average tree height（ 11.8 -14.9 m）and DBH （15.94-27.34 cm）under target tree management regime were significantly higher than that under extensive forest management regime（tree height is 7.1 - 11.0 m and DBH is 10. 18 - 19.00 cm） （P 〈0.05）. 3） Above 60% of treesunder extensive forest management regime and no disturbance regime were small-diameter tree（ DBH smaller than 12 cm） , but above 60% of trees under target tree management regime were middle-diameter tree （DBH 14 -18 cm）and large- diameter tree（ DBH above 20 cm）. 4） Diversity in tree layer under extensive forest management regime was higher than that under target tree management regime; exception of broad-leaved forest, diversity in shrub layer under extensive forest management regime was higher than that under target tree management regime; while diversity in herb layer under target tree management