Abstract: Facing the global climate change， fine root biomass，growth and turnover，longevity，seasonal dynamics and influence on the biogeochemical cycling in terrestrial ecosystems has gradually become a hot topic. Fine root is the plant root with diameter less than 2 mm and is an important part of the plant roots， as well as the most active part of the plant root system，which determine the growth and development of plants. Its productivity，dynamic and cycle play an important role in terrestrial ecosystem carbon cycle and in nutrient cycling. According to the previous studies，the amount of carbon entering the soil through fine root turnover accounted for about 30% to 50% of the whole ecosystem amount，and plant roots consume about 30% of the global net primary productivity. Therefore，it is of great significance to conduct research of effect of root biomass and turnover on soil carbon pool and the global carbon cycle. Plantation is an important part of the forest and plays an important role in carbon sequestration. Elaeagnus angustifolia L. plantations are common in the western desert region in China. However，there are no researches on the ability of [E. angustifolia] plantations at present. Previous studies mainly focused on natural forest communities，and in this research，plantations are focused. The continuous soil drilling method and fine root bag method was used to investigate the fine root dynamic and fine root turnover of E. angustifolia communities from May to October in 2010 （the whole growing season） at the Sangong River Basin，Changji Prefecture，Xinjiang，China. Fine root biomass of the [E. angustifolia ]shows the significant seasonal change and vertical distribution，the value of fine root biomass increased gradually from May to August，and reached maximum in August，then declined gradually from September to October. Monthly average fine root biomass was 146.24 g/m²，and live fine root biomass and dead fine root biomass were 73% and 27% of total fine root biomass，respectively. Fine root biomass reduced gradually as soil depth increased，and fine root biomass in 0-10 cm soil layer was the largest part，with 44.63% of total fine root biomass. Annual fine root decomposition rate was 58.5%，277 days and 1093 days were needed to reach half decomposition and 95% decomposition，respectively. Fine root net productivity was 151.99 g·m^-2·a^-1，and fine root annual turnover rate was 1.43 times/a. The study proves that the roots of E. angustifolia plantations have higher ability of carbon sequestration than that of the some natural communities，for example，Haloxylon ammodendron community. E. angustifolia plantations could be used widely in west desert region in China．

Key words: Elaeagnus angustifolia L, fine root turnover, biomass, soil organic carbon