中文摘要：

为了解巨桉人工林对土壤生态过程的影响，研究了1～10a生巨桉人工林林下土壤微生物数量及其生物量。结果显示，土壤细菌在土壤微生物类群中占绝对优势，放线菌次之、真菌数量最低，土壤细菌、放线菌、真菌、及微生物总数随土层加深而降低，偶尔出现逆向分布；各微生物类群及微生物数量呈现1～4a降低，而后显著增加。土壤微生物多样性指数，Pielou和Shannon-wiener指数轮伐期前（i～3或4a）有波动的增加，而后随林龄逐渐减小；Simpson指数呈相反趋势。

英文摘要：

In order to clearly understand the effects of eucalypt （Eucalyptus grandis） on soil eco- logical processes, soil microbial counts and microbial biomass were investigated in the Eucalyptus grandis plantations with a range of ages from 1 to 10 years. Bacteria quantitatively dominated the soil microbe community in eucalypt plantations regardless of plantation ages, followed by actino- mycete and fungi. Microbial counts decreased with soil depths except for the converse distribution in certain stands. The microbial counts decreased in eucalypt plantations from 1 to 4 years, and then increased with the increase of plantation age. Shannon-wiener index and Pielou index in- creased in the first 3 or 4 years and then decrease with the increase of plantation age, but Simpson index showed an opposite trend.