中文摘要：

研究荒漠草原区柠条人工林生长过程中土壤一植被系统演变特征，对于揭示柠条人工固沙林对沙化草地生态系统恢复产生的生态效应具有重要的科学意义．以6、15、24和36年生柠条人工林为对象，通过调查每个样地的土壤性质和地表植被特征，分析了荒漠草原区柠条人工林生长过程中土壤．地表植被的变化．结果表明：随着柠条人工林的发育，柠条的冠幅、树高、分枝数和基径极显著增加，土壤粗沙粒和细沙粒含量显著降低，极细沙和粘粉粒含量显著增加，土壤有机碳、全N和全P含量呈现线性增加，而土壤pH值则显著下降；地表植被物种数和密度显著增加，地表植被盖度和高度均表现为24年生〉15年生〉6年生〉36年生林地．相关分析表明，土壤质地、容重、土壤养分与pH值是影响柠条林地地表植被物种数、个体数和盖度分布的主要因素．在荒漠草原区，柠条人工固沙林发育过程有利于土壤条件改善和地表植被恢复，促进沙化草地生态系统的恢复．

英文摘要：

To study the variation characteristics of ground vegetation and soil properties during the growth process of Caragaua iutermedia plantations in desert steppe is of scientific significance in re- vealing the ecological effect of the plantations on the restoration of desertified grassland ecosystem. In this paper, an investigation was conducted on the ground vegetation and soil properties in 6-, 15-, 24-, and 36-yr artificial sand-fixing C. intermedia plantations in desert steppe of Ningxia, Northwest China, with the variation characteristics of the ground vegetation and soil properties dur- ing the growth process of the C. iutermedia plantations analyzed. With the growth and development of the plantations, the shrub crown width, height, sprout number, and basal diameter all increased significantly, the contents of soil coarse sand and fine sand had significant decrease while those of very fine sand and clay silt were in adverse, the soil organic carbon, total N, and total P contents increased linearly, and the soil pH decreased significantly. During the growth process of the planta- tions, the species number and individual number of ground vegetation increased significantly, and the vegetation coverage and height presented the order of 24- 〉 15- 〉 6- 〉 36-yr plantation. The soil texture, bulk density, nutrient contents, and pH value were the main factors affecting the spe- cies and individual number as well as the coverage of ground vegetation in C. intermedia planta- tions. It was suggested that in desert steppe, the growth process of artificial sand-fixing C. interme- dia plantation benefited the improvement of soil conditions and the recovery of ground vegetation, and promoted the restoration of degraded grassland ecosystem in desert steppe.