Abstract: [Objective] Wind-sand hazard is considered one of the most serious issues in oasis cities in northwestern China. Tree species, as a key part of city forest, provides a variety of ecological services and functions such as interception of dust, prevention of wind and sand, improvement of urban settlement environment etc. In this paper, Aksu city was taken as a case study, the city is located in an extreme arid zone and a typical oasis city in southern Xinjiang, China. Dust retention of eleven common tree species in roadside greenbelt of Aksu city and their economic value were quantified and valuated. The results will provide a theoretical basis for integrating the selecting criteria of urban greening species, optimizing management scheme of urban green areas and thus improving urban ecological construction and living environment in arid city.[Method] The cumulative dust retention per tree and unit area was estimated, and the difference of dust retention was analyzed based on the results of foliar elution method in May of 2014. Furthermore, the dust retention values of different tree species were calculated by conversion model.[Result] There were significant differences in dust retention per unit leaf area of different tree species. Dust retention capacity of tree species are as follows: Platanus acerifolia> Sophora japonica> Morus alba> Populus alba var. pyramidalis> Ulmus densa> Vitis vinifera> Pyrus×sinkiangensis> Elaeagnus angustifolia> Prunus cerasifera> Fraxinus sogdiana> Salix babylonica. The quantity of dust removed by Platanus acerifolia was the highest while Salix babylonica was the lowest, showing that the dust retention ability of Platanus acerifolia was nearly three times higher than that of Salix babylonica. The average economic value of dust removal by per hectare street greenbelt area in May was 3.28 yuan·hm^-2d^-1, and the estimated values of dust retention of different tree species were ordered as: Populus alba var. pyramidalis> Platanus acerifolia> Morus alba> Ulmus densa> Prunus cerasifera> Sophora japonica> Pyrus×sinkiangensis> Vitis vinifera> Elaeagnus angustifolia> Salix babylonica > Fraxinus sogdiana, with the highest value of 5.35 yuan·hm^-2d^-1 of Populus alba var. pyramidalis, and the lowest value of 2.01 yuan·hm^-2d^-1of Fraxinus sogdiana.[Conclusion] Under the same external environmental conditions, the capacity and economic value of dust retention were primarily determined by the tree species itself, particularly the leaf structure. Within a given period of time, the quantity of dust retention by trees gradually increases over time. Therefore, use of more local tree species with effective dust retention and wind-sand breaking capacities as many as possible would provide a powerful safeguard for urban landscape security, and for improving healthy development of oasis cities in arid area.

Key words: arid area, oasis cities, Aksu city, street green area, greening trees, dust retention, dust retention value