【摘要】 干旱半干旱区灌木、半灌木等木本植物的分布面积持续增加(灌丛化)显著改变了原有植被景观及生态过程，但缺乏对长期封育过程中灌木物种取代草本物种进而影响草地群落组成、结构和功能的研究。为揭示长期封育措施下典型草原灌丛化特征及地上/地下植物群落的响应规律，研究通过对宁夏云雾山典型草原同一封育草地不同时间(2010年、2016年、2021年)植物群落(物种重要值、丰富度、多样性和生物量)和土壤特性(土壤容重、土壤水分及储水量、养分、pH)的定点观测，探讨了长期封育过程中灌木物种矮脚锦鸡儿(Caragana brachypoda)驱动的植被和土壤特性变化。结果表明，(1)灌木矮脚锦鸡儿已经取代草本植物成为封育草地的优势种，群落中灌木生物量、总生物量以及盖度、高度显著增加，但对植物密度的影响较小；(2)灌丛化过程中草地群落Patrick丰富度指数、Simpson优势度指数和Shannon-Wiener多样性指数显著降低，而Pielou均匀度指数显著增加；(3)灌丛化引起土壤深层(60-100 cm)容重显著增大，土层储水量随土层深度的增加呈先减少后增加的趋势；(4)灌丛化使得土壤有机碳含量在浅层(0-60 cm)显著增大；土壤全氮含量在深层(60-100 cm)显著增大；土壤全磷含量在各土层都显著增加。研究发现，草地灌丛化改变了群落地上-地下过程，且植被和土壤的响应可能存在不同步性。研究结果可为群落演替和草地稳态理论以及灌丛化草地的适应性和可持续管理提供一定的理论和实践支撑。更多还原

【Abstract】 The distribution area of shrubs or subshrubs continues to increase in arid and semi-arid areas(shrub encroachment),which could significantly change the original vegetation landscape and ecological process, but there was a lack of research on shrub species replacing herbaceous species in the long-term enclosure process, which affected the composition, structure and function of grassland communities. In order to reveal the response characteristics of enclosed grassland vegetation and soil to shrub encroachment, authors investigated the response of long-term enclosed grassland vegetation and soil characteristics to Caragana brachypoda encroachment by site observation of plant community(species importance value, richness, diversity and biomass) and soil characteristics(soil moisture, nutrients, pH) at different times(2010, 2016 and 2021) in the same enclosed grassland in semi-arid loess area. The results showed that,(1) Caragana brachypoda had replaced herbaceous plants as the dominant species of enclosed grassland. The shrub biomass and total biomass and the coverage and height increased significantly, while the community density was less affected.(2) The Patrick richness index, Simpson diversity index and Shannon-Wiener diversity index of grassland community were significantly decreased, while the Pielou evenness index was significantly increased due to the encroachment of Caragana brachypoda.(3) Shrub encroachment caused a significant increase in soil bulk density in the deep layer(60-100 cm), and the soil water storage showed a trend of first decreasing and then increasing with the increase of soil depth.(4) Shrub encroachment significantly increased the soil organic carbon content in the shallow layer(0-60 cm); the total nitrogen content had a significant increase in the deep layer(60-100 cm); and the total phosphorus content in each soil layer was significantly increased. The results showed that shrub encroachment changed the aboveground-underground process of grassland community, and the response of vegetation and soil might be inconsistent. This research results could provide theoretical and practical support for community succession and grassland steady-state theory, as well as the adaptability and sustainable management of shrub-encroached grasslands.更多还原