Soil Enzyme Activities Under Plant Communities in Saline-sodic Grassland in Songnen Plain

Field sampling and lab testing method were used to study the alkaline phosphatase,urease,sucrase activities and the vertical distribution of these soil enzyme activities in Leymus chinensis,Phragmite communis,Chloris virgat,Puccinellia tenuiflor,Suaeda glauca plant communities and the saline-sodic wasteland and to analyze the correlation of the three soil enzyme activities and the soil physical and chemical properties.The results showed that the alkaline phosphatase,urease and sucrase activities in the Leymus chinensis community were the highest,which were higher in the Phragmite communis and Chloris virgata communities,soil enzyme activities in the Suaeda glauca community were the lowest,which was close to these in the saline-sodic wasteland.The soil enzyme activities were decreased with the soil depth increased,soil enzyme activities in the surface layer was the largest in all root layers,which accounted for about 50% of the total soil enzyme in the root layers.Soil enzyme activities had negative correlation with electrical conductivity(EC) and pH value but had positive correlation with soil nutrients.The EC and pH values had great influences of the soil enzyme activities,the correlation of urease activity and soil nutrients were significant,but was not obvious between sucrase activity and soil nutrients.