中文摘要：

采用Bremner氮素分级方法,研究冻融交替对高寒草甸土壤微生物量氮和有机氮组分的影响.结果表明：随着冻融时间的变化,微生物量氮含量先减少后增加,在冻融1 d后达到最小值,4℃、-4℃、-4～4℃和-20～4℃处理下分别下降了50.37%、57.47%、37.79%和37.51%;氨基酸氮和氨基糖氮变化趋势相同,先增加后减少,均在冻融1 d后达到最大值,各处理氨基酸氮含量分别为处理前的1.6倍、1.47倍、1.44倍和1.5倍,氨基糖分别为处理前的1.66倍、1.58倍、1.65倍和1.91倍;氨态氮含量先增加后减少,-20～4℃处理在冻融1 d后为处理前的1.25倍,其余3个处理在冻融3 d后达到最大值;各处理酸解未知氮的变化趋势大体相同,在冻融25 d后达到最小值.研究表明冻融时间对微生物量氮和有机氮组分影响显著,微生物量氮含量是有机氮组分变化的主要原因.

英文摘要：

The effects of freezing and thawing cycles on microbial biomass nitrogen and organic nitrogen in the alpine meadow soil were investigated by the Bremner nitrogen classification method.The results indicated that with the change of the freezing and thawing cycles,microbial biomass nitrogen of all the treatments decreased first and reached the minimum after one cycle,and then increased a little.Microbial biomass nitrogen of treatments 4 ℃,-4 ℃,-4～4 ℃ and-20～4 ℃ declined by 50.37%,57.47%,37.79% and 37.51%,respectively.However,amino acid nitrogen and amino sugar nitrogen increased first and then decreased,which all peaked after one cycle.The contents of amino acid nitrogen of each treatment were 1.6 times,1.47 times,1.44 times and 1.5 times higher than those in the initial days respectively.The contents of amino sugar nitrogen were 1.66 times,1.58 times,1.65 times and 1.91 times than those in the initial days respectively.Contents of ammonium nitrogen rose up first and then declined,-20～4 ℃ treatment was 1.25 times higher than that in the initial days,while the other three treatments peaked after three cycles.Unidentified hydrolizable nitrogen of each treatment varied as the same in general,which all reached the minimum after 25 cycles.The results showed that the effects of freezing and thawing time were obvious on microbial biomass nitrogen and organic nitrogen,and content of microbial biomass nitrogen was the main reason for organic nitrogen change.