Studies On Nitrogen Mineralization And Enzymatic Activities Of Forest Soil In Xishan Of Beijing

In this study,the upper soil samples(0-10cm) were collected from four different types of plantation (Pinus tabulaeformis,Platycladus orientalis,Acertruncatum,Cotinuscoggygria) to evaluate the variation of soil nitrogen mineralization.Variation in ammonium nitrogen,nitrate nitrogen and N mineralization was investigated using the Closed-Top Tube Incubation method,the activity of soil enzymes under different vegetation types were studied by lab analyzing,this essay discussed the relationship between forest soil N mineralization,soil nutrients and enzymes activities,as well as the relations among the different types of soil enzymes.This research is benefit for the inspection of mountainous region soil quality system in Xishan of Beijing,simultaneously,the result also provide the basis to the rational use of forest land resources.The results showed that:(l) the highest rate of N mineralization under different plantations appears in August,the soil N mineralization in Acertruncatum is higher than other types,the rate of N mineralization in Platycladus orientalis and Pinus tabulaeformis is lower than others.The soil NH4-N is higher than NO₃-N under Acertruncatum and Cotinuscoggygria in differert seasons.(2) The activity of different soil enzymes in Platycladus orientalis is the lowest,and the highest rate showed in Acertruncatum.The activity of urease,protease,β-glucosidase,acid phosphatase and alkaline phosphatase is higher than other months.The activity of alkaline phosphatase is higher than acid phosphatase under Acertruncatum and Cotinuscoggygria in every months.(3) The soil N mineralization is positive correlation to urease and protease.Alkaline phosphatase,β-glucosidase is positive correlation to soil N mineralization except Cotinuscoggygria.(4) Principal component analysis showed that the first principal components is positive correlation to all the enzymes,the seconed principal components is positive correlation to urease and protease,and negative correlation toβ -glucosidase,acid phosphatase and alkaline phosphatase(5) The protease is positive correlation to alkaline phosphatase,β-glucosidase is positive correlation to acid phosphatase in all types of plantations.This research determined the seasonal variation of soil N mineralization in differert plantations and discussed the relations among the soil N mineralization and different types of enzymes in Xishan of Beijing for the first time.