三江源区不同建植年限对人工草地土壤微生物功能多样性的影响

Effects of cultivation duration on soil microbial functional diversity of artificial grassland in the Three-River Headwater Region

明确三江源区不同建植年限人工草地土壤微生物功能多样性的变化规律,探索高寒地区人工草地恢复措施,可以为退化高寒草甸恢复治理提供理论依据。试验于2014年8月在青海省果洛州选择建植4年、8年和12年的多年生禾本科人工草地为试验样地,利用常规实验室分析和Biolog-ECO生态板法对土壤养分和土壤微生物功能多样性进行分析。结果表明:在0~10 cm土层,土壤pH与TN含量在建植4年显著高于其他建植年限;TK和速效养分含量随建植年限增加而升高;在10~20 cm土层,土壤pH在建植4年显著大于其他年限;TK含量在建植12年时显著小于其他年限,AN和AK则呈现建植8年>12年>4年;AWCD值在0~10 cm土层表现为建植8年>12年>4年,而在10~20 cm土层随建植年限的增加而增加;在0~10 cm土层,Shannon指数和Pielou指数均是建植12年显著小于建植4年和8年;在10~20 cm土层,Mc Intosh指数表现出建植12年>8年>4年,且差异显著,而Shannon指数和Pielou指数则表现出建植4年显著小于8年和12年。主成分分析表明,氨基酸类和酯类是土壤微生物利用的主要碳源类型。冗余分析表明,有机碳、速效钾、速效氮、全钾和pH是影响不同建植年限人工草地土壤微生物功能多样性和代谢活性的主要因子。不同建植年限人工草地土壤微生物功能多样性存在差异,随着建植年限的增加,土壤养分状况、微生物群落稳定性和生态环境得到改善。

The objective of the current study is to reveal the changes of soil microbial functional diversity in the artificial grassland with different cultivation periods in the Three-River Headwater Region, so as to provide evidence to ameliorate the degraded alpine meadow based on the efforts of planting artificial grassland. Three artificial grasslands with cultivation durations of 4, 8 and 12 years were selected. Soil nutrients and microbial functional diversity were determined using con- ventional laboratory analysis and the Biolog-ECO microplate method. In the 0-10 cm soil layer, soil pH and total nitrogen （TN） content were significantly greater with 4 cultivation years than with the other euhivation years, while total potassium （TK） and available nutrients increased with increasing cultivation years （P〈0.05）. In the 10-20 em soil layer, soil pH was significantly higher in 4-year grassland than in the other grasslands, while TK in 12-year grassland was signifi- cantly lower than in the other grasslands （P〈0.05）. Additionally, available nitrogen （AN） and available potassium （AK） showed the following pattern： 8 years 〉 12 years 〉 4 years. In the 0-10 cm soil layer, average well color development （AWCD） value showed 8 years 〉 12 years 〉 4 years. But AWCD value increased with increasing cultivation years in the 10-20 cm soil layer. Soil microbial functional diversity showed that Shannon and Pielou index in 0-10 cm soil layer of the 12-year grassland were lowest, while in the 10-20 cm soil layer the least values were found in the 4-year grassland. McIntosh index increased with increasing cultivation years in the 10-20 cm soil layer. Principal component analysis （PCA） showed that amino acids were the main car- bon source for maintaining soil microbial community. Redundancy analysis （RDA） indicated that soil organic carbon （SOC）, TK, AN, AK and pH were the main factors influencing the metabo- lic rate of soil microbial community and microbial functional diversity. In summary, there were differences among soil microbial functional diversity in the artificial grasslands of different cultiva- tion durations. Soil nutrient content, soil microbial community stability and ecological environ- ment improved with increasing cultivation years.