藏北高寒草地土壤有机质化学组成对土壤蛋白酶和脲酶活性的影响

土壤酶作为生态系统的生物催化剂, 是土壤有机体的代谢驱动力, 在土壤物质循环和能量转化过程中起着重要作用。该研究以藏北5种不同类型高寒草地(高寒草甸、高寒草原、高寒草甸草原、高寒荒漠草原和高寒荒漠)为研究对象, 利用热裂解气质联用技术(Py-GC/MS)分析不同类型草地土壤有机质化学组成, 并建立其与土壤蛋白酶和脲酶活性之间的相互关系。结果表明, 5种高寒草地土壤(0-15 cm)的酶活性表现出一定差异性, 高寒荒漠草原土壤的脲酶活性显著高于蛋白酶活性, 而其余类型高寒草地的脲酶和蛋白酶活性之间的差异未达到显著水平; 蛋白酶活性在5种高寒草地土壤之间的差异显著, 而脲酶活性在5种草地土壤之间的差异未达到显著水平。相关分析发现, 土壤蛋白酶活性与土壤有机质烷烃、烯烃和芳香烃的相对丰度和糠醛:吡咯的值密切相关, 土壤脲酶活性与土壤有机质化学组成之间相关性未达到显著水平。综上所述, 高寒草地类型和土壤有机质化学组成是影响高寒草地土壤蛋白酶活性的重要因素, 而对土壤脲酶活性的影响均未达到显著水平, 其影响因素有待进一步深入的研究。

Effect of soil organic matter chemical compositions on soil protease and urease activity in alpine grassland soils in Northern Xizang,China

Aims Soil enzymes play an important role in the process of soil nutrient transformation. The main purpose of this study is to explore the chemical composition of soil organic matter and its effect on soil protease and urease activity in alpine grasslands in Northern Xizang, China.Methods The pyrolysis Gas Chromatograph/Mass Spectrometer (Py-GC/MS) was used to obtain the chemical compositions of soil organic matter, and to analyze the relationships between soil chemical compositions and soil enzyme activity in five alpine grasslands, including alpine meadow, alpine steppe, alpine meadow steppe, alpine desert steppe and alpine desert ecosystems.Important findings The results showed that the enzyme activities among five alpine grassland soils (0-15 cm) were different. Soil urease activity was significantly higher than soil protease activity in the alpine desert steppe, while the difference between the urease and protease activities was not significant in other types of alpine grasslands. Soil protease activity was significantly different among five alpine grassland types, but soil urease activity was not. The correlation analysis showed that soil protease activity was closely related to the relative abundance of alkanes, alkenes and aromatics in soil organic matter and the ratio of furfural to pyrrole. However, the correlation relationships between urease activity and soil organic matter chemical compositions were not significant. The results indicated that alpine grassland type and soil organic matter chemistry were the key factors affecting soil protease activity, but their effects on soil urease activity was non-significant, which calls for further study on the influencing factors on soil urease activity.