气候变化对草甸草原土壤氮素矿化作用影响的实验研究

 用盖顶PVC管法，将锡林河流域中1469m高海拔处的草甸草原原状土柱分别移植到海拔1187m、960m的低海拔处培养，用以研究温度变化对土壤氮素的净氨化速率、净硝化速率和净矿化速率的可能影响。经过一个生长季培养后的测定结果表明：从高海拔到低海拔，实验所选择的3个地点的年均气温分别为-0.5℃、2.2℃和4.4℃，受此不同气温的影响，移植到这3个地点的草甸草原土壤氮素的净氨化速率分别为0.05 mgN·kg-1·m-1，0.13mgN·kg-1·m-1和1.09mgN·kg-1·m-1；净硝化速率分别为0.05mgN·kg-1·m-1，0.76mgN·kg-1·m-1和0.26mgN·kg-1N·m-1；净矿化速率分别为0.10mgN·kg-1·m-1，0.89mgN·kg-1·m-1和1.35mgN·kg-1·m-1。由此可推断未来气候变化将促进草甸草原土壤氮素的净矿化作用。

FIELD EXPERIMENTAL STUDIES ON THE EFFECTS OF CLIMATE CHANGE ON NITROGEN MINERALIZATION OF MEADOW STEPPE SOIL

We assessed the potential impact of global warming on rates of net ammonification, net nitrification and net mineralization of soil nitrogen by transferring intact soil cores (0-15 cm) from 1469 m higher-elevation meadow steppe to 1187 m and 960 m lower-elevation sites respectively in the Xilin River Basin of Inner Mongolia. After incubation for one growing season, ammonium nitrogen and nitrate nitrogen (including nitrite nitrogen) of the soil samples were determined. The annual mean air temperature at the three selected study sites during the field study was, from higher-to lower-elevation, -0.5℃, 2.2℃ and 4.4℃ respectively. Affected by these different air temperature regimes, the net ammonification rate was 0.05 mgN·kg-1·m-1, 0.13 mgN·kg-1·m-1, 1.09mgN·kg-1·m-1. Correspondingly,the net nitrification rate was respectively 0.05mgN·kg-1·m-1, 0.76 mgN·kg-1·m-1 and 0.26mgN·kg-1·m-1,and the net mineralization rate was 0.10mgN·kg-1·m-1, 0.89mgN ·kg-1·m-1 and 1.35 mg N·kg-1·m-1 in the soil transferred to the three sites. Hence we conclude that increasing air temperature will enhance soil N mineralization.