青藏高原典型高寒草地土壤化学性质和酶活性特征OA

[Objective]To investigate the distribution patterns of soil enzyme activities and their influencing factors in different alpine grassland types on the Tibetan Plateau.[Methods]Three typical alpine grasslands widely distributed on the Tibetan Plateau were selected as research subjects:alpine swamp meadow(ASM),alpine meadow(AM)and alpine steppe(AS).The activities of four enzymes were measured in the 0-100 cm soil profiles,and the effects of soil chemical properties on enzyme activities in different alpine grassland types were analyzed.[Results]1)The mass fractions of soil organic carbon,total nitrogen,total phosphorus,total potassium,and ammonium nitrogen followed the order:ASM>AM>AS(p<0.05).The mass fraction of nitrate nitrogen was highest in AS(0.83 mg/g).The soil of all three alpine grassland types exhibited slightly alkaline pH conditions.As soil depth increased,soil nutrient contents gradually decreased,while pH gradually increased.2)The soil sucrase activity in ASM was significantly higher than that in AM and AS,increasing by 4.51%and 83.18%,respectively(p<0.05).The activities of soil urease,alkaline phosphatase,and catalase followed the order:AM>ASM>AS(p<0.05).All four soil enzyme activities decreased with increasing soil depth.3)Soil organic carbon had the most significant influence on soil enzyme activities in ASM and AM,with contribution rates of 96.60%and 89.20%,respectively(p<0.05).The main environmental factors influencing soil enzyme activities in AS were soil nitrate nitrogen and pH,with contribution rates of 55.30%and 24.90%,respectively(p<0.05).[Conclusion]Soil enzyme activities were significantly different among different types of alpine grassland,and organic carbon,nitrate nitrogen and pH were the important regulatory factors.The results can provide scientific references for revealing the mechanisms of soil enzyme activity variations and their responses to climate warming in alpine grassland ecosystem,as well as a scientific basis for understanding nutrient cycling patterns in alpine grassland soil and formulating grassland management strategies.