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以小兴安岭湿地土壤为研究对象,基于室内分析和冻融实验,分析了冻融作用下不同年代排水造林湿地土壤微生物量、酶活性以及有机碳密度的变化趋势,探讨了不同年代排水造林湿地土壤微生物活性与有机碳密度之间的相关关系,以期为深入认识冻融期间高寒高纬度地区土壤碳循环过程提供参考依据。结果表明:(1)冻融次数对土壤微生物量碳、氮含量影响显著(P<0.05),经历9次冻融循环后,土壤微生物量碳、氮含量比冻融前明显减少;在三种不同年代排水造林的湿地中,排水时间越短,土壤微生物量碳、氮含量下降幅度越大,表明长时间的反复冻融交替可能导致土壤微生物量的进一步减少。(2)冻融前后,土壤蔗糖酶和淀粉酶活性均表现为下降趋势,且多次冻融交替后,-25~5℃冻融处理比-5~5℃冻融处理酶活性更低,表明较大的冻融温差更能降低土壤酶的活性度。(3)随着冻融次数和冻融温度的变化,四种湿地的土壤有机碳密度基本保持稳定,但其与土壤微生物量、酶活性却存在着高度的正相关性,通过探究微生物活性所调控的土壤过程,可以直接或间接了解土壤有机碳密度的变化趋势,便于从本质上验证其响应机制。
Taking Xiaoxing’anling wetland soil as the research object, the change trend of soil microbial biomass, enzyme activity and organic carbon density in different years of wetland-wetland wetland was analyzed based on indoor analysis and freeze-thaw experiment. The effects of different ages on soil microbial Activity and organic carbon density in order to provide a reference for in-depth understanding of soil carbon cycling in high-cold and latitude regions during freezing and thawing. The results showed that: (1) The number of freeze-thaw cycles had a significant effect on soil microbial biomass C and N (P <0.05). After 9 freeze-thaw cycles, the soil microbial biomass carbon and nitrogen contents decreased significantly compared with those before freeze- In the wetland with different times of drainage and afforestation, the shorter the drainage time is, the greater the declining rate of soil microbial biomass carbon and nitrogen is, which indicates that prolonged repeated freeze-thaw cycles may result in the further reduction of soil microbial biomass. (2) The activities of soil invertase and amylase showed a decreasing trend before and after freezing and thawing, and after multiple freeze-thaw cycles, the activities of freezing and thawing at -25 ~ 5 ℃ were lower than those at -5 ~ 5 ℃, Show that the larger the temperature difference between freezing and thawing can reduce the activity of soil enzymes. (3) With the change of freeze-thaw times and freeze-thaw temperature, the soil organic carbon density in four wetlands basically remained stable, but there was a highly positive correlation with soil microbial biomass and enzyme activity. By investigating the activity of microorganisms The controlled soil processes can directly or indirectly understand the trend of soil organic carbon density and facilitate the verification of its response mechanism in essence.