Abstract: By using resin core method, the intact soil in a high altitude montane evergreen broadleaved forest in Ailao Mountains was transferred to and incubated in the medium altitude secondary forest and low altitude artificial forest in the Mountains, respectively, aimed to study the altitudinal effect of soil nitrogen transformation. Altitude had significant effects on the net mineralization rate, net nitrification rate, and leached amount of soil nitrogen (P<0.01), being most obvious in early rain season. At high altitude, the soil nitrogen net mineralization and net nitrification rates were -5.81 and -4.18 mg N·kg^-1·60 d^-1,respectively; while at medium and low altitudes, they were 20.92 and 44.15 mg N·kg^-1·60 d^-1, and 17.07 and 20.38 mg N·kg^-1·60 d^-1, and the amount of leached nitrogen was increased by 0.37 and 2.77 times, respectively.Due to the increase of soil denitrification in mid and late rain seasons,the soil nitrogen net mineralization and net nitrification rates decreased, with the net mineralization rate peaked in mid rain season and decreased in late rain season. It was deduced that the future climate warming could accelerate the soil nitrogen transformation rate and cause the gaseous nitrogen losses in the montane evergreen broadleaved forest of Ailao Mountains.

Key words: Township agroecosystems, Structure and function, Cluster analysis, Correlation analysis