采用群落调查法对内蒙古阿拉善梭梭〔Haloxylon ammodendron (C. A. Mey.) Bunge〕人工林进行植物群落踏查，根据Shannon指数、Levins指数和Pianka指数对梭梭人工林林下灌木层和草本层主要植物的生态位宽度、生态位重叠进行分析，采用方差比率、χ2检验、联结系数分析种间联结性。结果表明：内蒙古阿拉善梭梭人工林林下灌木层植物有25种，草本层植物有25种，其中，灌木层主要植物16种，草本层主要植物14种。梭梭人工林林下红砂〔Reaumuria songarica (Pall.) Maxim.〕、白刺(Nitraria tangutorum Bobrov)、泡泡刺(Nitraria sphaerocarpa Maxim.)、骆驼蓬(Peganum harmala Linn.)、盐生草〔Halogeton glomeratus (M. Bieb.) C. A. Mey.〕、雾冰藜〔Bassia dasyphylla (Fisch. et C. A. Mey.) Freitag et G. Kadereit〕的生态位宽度优势明显。阿拉善梭梭人工林灌木层16个主要植物组成的120个种对中有116个种对的Pianka指数小于0.53，草本层14个主要植物组成的91个种对中有90个种对的Pianka指数小于0.77。灌木层和草本层物种总体生态位重叠较低，总体联结性为显著负联结。χ2检验结果表明:灌木层中正联结种对24个，负联结种对96个；草本层中正联结种对25个，负联结种对66个。联结系数分析结果表明：灌木层正联结种对2个，无联结种对30个，负联结种对88个；草本层中正联结种对1个，无联结种对32个，负联结种对58个。综合研究结果显示：阿拉善梭梭人工林林下群落处于不稳定演替阶段，多数物种对资源利用的相似程度低。生境差异可能是造成林下物种生态位重叠较低，物种间以负联结为主的主要原因。

A plant community survey was conducted on the Haloxylon ammodendron (C. A. Mey.) Bunge plantations in Alxa of Inner Mongolia by using the community survey method, the niche width and niche overlap of the main plants in the shrub and herb layers under H. ammodendron plantations were analyzed based on the Shannon index, Levins index, and Pianka index, and the interspecific associations were analyzed by using variance ratio, χ2 test, and association coefficient. The results show that there are 25 species in the shrub layer and 25 species in the herb layer under H. ammodendron plantations in Alxa of Inner Mongolia, among which, there are 16 main plants in the shrub layer and 14 main plants in the herb layer. Reaumuria songarica (Pall.) Maxim., Nitraria tangutorum Bobrov, Nitraria sphaerocarpa Maxim., Peganum harmala Linn., Halogeton glomeratus (M. Bieb.) C. A. Mey., and Bassia dasyphylla (Fisch. et C. A. Mey.) Freitag et G. Kadereit under H. ammodendron plantations show evident advantages in niche width. In the shrub layer under H. ammodendron plantations in Alxa, 116 out of 120 species pairs composed of 16 main plants have a Pianka index smaller than 0.53, while in the herb layer, 90 out of 91 species pairs composed of 14 main plants have a Pianka index smaller than 0.77. The overall niche overlap of the species in the shrub and herb layers is low, and the overall association is significant negative association. The χ2 test result shows that there are 24 positively associated species pairs and 96 negatively associated species pairs in the shrub layer;  25 positively associated species pairs and 66 negatively associated species pairs in the herb layer. The association coefficient analysis result shows that there are 2 positively associated species pairs, 30 non-associated species pairs, and 88 negatively associated species pairs in the shrub layer, and 1 positively associated species pair, 32 non-associated species pairs, and 58 negatively associated species pairs in the herb layer. The comprehensive research results indicate that the community under H. ammodendron plantations in Alxa is in an unstable succession stage, with a low degree of similarity in resource utilization of most species. Habitat differences may be the main reason for the low niche overlap of the species in the understory and the predominance of negative associations among species.