To explore the influence of urban grassland types on soil DOC and its characteristics， this study took the urban green space ecosystem in Beijing as research object. Four treatments were established： bare land， cool-season grassland， warm-season grassland， and urban understory ground cover. The soil DOC content was measured， and the spectral characteristics of soil dissolved organic matter （DOM） were analyzed by using ultraviolet-visible spectroscopy and three-dimensional fluorescence spectroscopy. The results showed that compared to the bare land， the DOC content of the cool-season grassland surface soil was significantly decreased by 30% （P<0.05）， but there was no significant difference from warm-season grassland and urban understory ground. The UV spectra showed there was no significant difference between the aromaticity and the hydrophobicity of the DOM among the treatments. The fluorescence spectra showed that the DOM of urban grasslands had mixed source characteristics. In compared with the bare land， the humization process of the urban grasslands was enhanced but self-source contribution was decreased， with strong microbial activity but weak bio-availability. The results showed that the dynamic of DOC in urban grassland was regulated by vegetation type， management measures and microbial activity. The optimization of fertilization management and the consideration of carbon sequestration type of grass species could enhance the function and stability of urban soil carbon sequestration， which provided theoretical support for the improvement of urban green space ecological function.

Urban lawn  /  Vegetation types  /  Dissolved organic carbon  /  UV-fluorescence absorption characteristic