以贵州省喀斯特山地的干香柏（Cupressus duclouxiana Hichel）纯林、刺槐（Robinia pseudoacacia Linn.）纯林和干香柏-刺槐混交林3种人工林为研究样地，并以未造林地为对照样地，采用植物群落调查法和收获法研究了各样地林下灌木层和草本层植物的物种组成、多样性特征及地上部生物量，并分析了林下地上部生物量与植物多样性的相关性。结果显示：在3种人工林和未造林地中共包含林下植物49科84属92种，其中，干香柏-刺槐混交林的物种最丰富。3种人工林和未造林地灌木层和草本层的优势种类存在一定差异，但齿叶冬青（Ilex crenata Thunb.）和小果蔷薇（Rosa cymosa Tratt.）是3种人工林灌木层共有的优势种，且小果蔷薇也是未造林地的优势种；而青绿薹草（Carex breviculmis R. Br.）则是3种人工林草本层共有的优势种。3种人工林灌木层和草本层的Margalef丰富度指数、Simpson优势度指数和Shannon-Wiener多样性指数均高于未造林地，且总体上以干香柏-刺槐混交林为最高，并与未造林地存在显著（P＜0.05）差异；而供试4个样地间灌木层和草本层的Pielou均匀度指数总体上无显著差异。3种人工林灌木层地上部生物量均高于草本层，占地上部总生物量的55.58%～68.04%；而未造林地灌木层地上部生物量低于草本层，仅占地上部总生物量的26.81%。干香柏-刺槐混交林的灌木层地上部生物量、草本层地上部生物量和地上部总生物量均显著高于未造林地。3种人工林和未造林地灌木层和草本层的地上部生物量和地上部总生物量仅与少数多样性指数有显著或极显著（P＜0.01）相关性，但无明显规律性。综合分析结果表明：人工林林下植物的物种组成、多样性特征和地上部生物量不同程度优于未造林地，且林下地上部生物量与植物多样性的关系存在一定差异，环境异质性差异和生物学特性复杂性是其主要致因；总体上，营造干香柏-刺槐混交林有利于提升林下植物多样性和地上部生物量，建议在喀斯特退化山地人工植被恢复中采用针阔混交林种植方式。

 Taking 3 plantations of pure forest of Cupressus duclouxiana Hichel， pure forest of Robinia pseudoacacia Linn. and mixed forest of C. duclouxiana-R. pseudoacacia in karst mountainous region of Guizhou Province as the research plots， and unforested land as the control plot, the species composition， diversity characteristics and above-ground biomass of plants of undergrowth shrub and herb layers in each plot were studied by plant community survey and harvest methods， and the correlation between undergrowth above-ground biomass and plant diversity was analyzed. The results show that there are 92 species in 84 genera of 49 families of undergrowth plants in 3 plantations and unforested land， in which， the species of mixed forest of C. duclouxiana-R. pseudoacacia is the most abundant. There are some differences of dominant species of shrub and herb layer of 3 plantations and unforested land, but Ilex crenata Thunb. and Rosa cymosa Tratt. are the common dominant species in shrub layer of 3 plantations, meanwhile R. cymose is also one of the dominant species in unforested land; while Carex breviculmis R. Br. is the common dominant species of herb layer of 3 plantations. The Margalef richness index， Simpson dominance index and Shannon-Wiener diversity index of shrub and herb layers of 3 plantations are higher than those of unforested land， and those of mixed forest of C. duclouxiana-R. pseudoacacia are the highest in general， and are significantly （P＜0.05） different from unforested land； but there is no significant difference in Pielou evenness index of shrub and herb layers among 4 test plots in general. The above-ground biomass of shrub layer of 3 plantations is higher than that of herb layer， accounting for 55.58%-68.04% of the total above-ground biomass； while the above-ground biomass of shrub layer of unforested land is lower than that of herb layer， only accounting for 26.81% of the total above-ground biomass. The above-ground biomass of shrub layer， above-ground biomass of herb layer and total above-ground biomass of mixed forest of C. duclouxiana-R. pseudoacacia are significantly higher than those of unforested land. The above-ground biomasses of shrub and herb layers and total above-ground biomasses of 3 plantations and unforested land only have significant or extremely significant （P＜0.01） correlation with a few diversity indexes， but there is no obvious regularity. The comprehensive analysis result shows that the species composition， diversity characteristics and above-ground biomass of undergrowth plants in plantation are better than those in unforested land to different extents， and there are some differences in relationship between undergrowth above-ground biomass and plant diversity， which is mainly caused by difference in environmental heterogeneity and complexity of biological characteristics； in general， the construction of mixed forest of C. duclouxiana-R. pseudoacacia is beneficial to the elevation of diversity and above-ground biomass of undergrowth plants， therefore, it is suggested that planting pattern of coniferous and broad-leaved mixed forest can be used in the restoration of artificial vegetation in karst degraded mountainous region.