Abstract: To ascertain the purification capacity of urban forest soil of different forest types for treating sewage and provide scientific basis for the configuration of waterfront shelter forests, we selected three forest types (Quercus mongolica plantation, Fraxinus mandshurica plantation, Phellodendron amurense plantation) in the demonstration base of urban forest in Harbin as the research object and bare land as the control. The Majiagou sewage was collected for indoor simulated irrigation. The compositions of soil column leachate following irrigation were measured. The results showed that the removal effects of ammonium in the three forest soils were significant (P<0.05). The ammonium absorbed in the soil column was not different among three forest soils, which was also not significant from the control (P>0.05). The concentration of nitrate in leachate from the soil columns in three forest types and the control increased significantly as compared with the sewage without soil column filter (P<0.01), which increased with the water inflow. The quality of nitrate leached from the soil column of three forest types was lower than that of the control, but the difference was not significant (P>0.05). The pH of leachate from the soil columns of three forest types and the control was significantly lower than that without soil column filter. The dissolved oxygen in leachate from the soil columns of each forest type was higher than that without soil column filter, but the difference was not significant. Except for the Q. mongolica plantation, the redox potential, electrical conductivity, and total dissolved solids in the leachates from soil columns of other two forest types and the control increased significantly compared with the sewage without filtered soil column.

Key words: competitiveness, brassinolide, nitrogen fertilization, biomass allocation