关键词: 塔克拉玛干沙漠, 咸水灌溉, 人工绿地, 土壤酶活性

Abstract: Artificial plantation had been set up by irrigating saline water(salt content is 4~5 g·L^-1) for 4 years in the extremely arid region,the center of Taklimakan Desert.The plant included Tamarix,Haloxylon,Calligonum,many vegetables and flowers etc.The soil characters of artificial plantation fields have been changed greatly compared to the characters of the original soils,and soil enzyme activities have been changed too.The soil enzyme activities correlated highly with the soil fertility,and it can be regarded as one of the important index of soil formation and fertility level.This article analyzed several soil enzyme activities-sucrase,protease,urease,neutral phosphcrease,alkaline phosphcrease and H₂O₂ enzyme activities,which are important to the circulation and transformation of Carban,Nitrogen,Phosphoms in soil,in order to find out the relationship between environment and soil enzyme activities during the desert reformation,to deduce the development direction and level of soil fertility,to evaluate the reformation effect of artificial plantation,and to provide scientific basis for using desert rationally.The authors selected 10 representative fields to take samples,which included different plant ages,species and managing patterns,and the depth of taking samples is 0~10 cm and 10~50 cm.After analyzing the soil enzyme activities of these samples,the result shows:1.Because of the absence of plant and the unstability of ground,the original soil enzyme activities are very low.After artificial plantation had been set up,plant,soil microorganisms and soil nutrient content all increased greatly.The soil enzyme is from the tree root,soil microorganisms and the remains of plants and animals,so the soil enzyme activities in artificial plantation fields were higer than that in the original soils,and increased with plant age.Because of the differences of soil fertility in different sample fields,the soil enzyme activities varied in the sample fields of different vegetation and managing patterns of the same plant age.Such as,planted for one year,the soil enzyme activities in flower field were higher than that in grassland and in growing seedlings field;and planted for three years,the soil enzyme activities in vegetable field were higher than that in growing seedlings field and in afforestation field.2.The soil enzyme activities were higher in topsoil layers than in subsoil layers,because the soil nutrient content,tree roots and soil microorganisms reduced with the depth of soil horizon drops.3.Apart from H₂O₂ enzyme,all kinds of soil enzyme activities were highly correlated with the soil organic matter,nitrogen,phosphorus and the amount of soil microorganisms.Protease,urease,phosphcrease activities showed highly significant correlation(at 1% level) with organic matter(at 5% level);total phosphorus showed no correlation with these enzyme activities,but highly significant correlation was found with solute phosphorous.Protease,urease activities showed significant correlation with total nitrogen and solute nitrogen;phosphcrease activity showed significant correlation with solute nitrogen and highly significant correlation with total nitrogen.Besides H₂O₂ enzyme activity showed significant correlation with soil microorganism,all kinds of other soil enzyme activities showed highly significant correlation with soil microorganisms.4.These soil enzyme activities in Taklimakan Desert sand dunes are lower than that in semi arid and semi humid region deserts of China.The circumstance in Taklimakan Desert is more bitter than that in other regions.There is short of water and vegetation more seriously,and the artificial plantation had been set up for short time,the level of soil formation is in original stage and the level of soil fertility is very low.

Key words: Taklimakan Desert, irrigating by saline water, artificial plantation, soil enzyme activity