不同林龄华北落叶松白桦混交林土壤微生物量碳氮含量研究

Research on Soil Microbial Biomass Carbon and Nitrogen in Larch-Betula platylla Mixed Forests of Different Ages

以山西太岳山15a,20a和25a华北落叶松白桦混交林为研究对象,研究其土壤微生物量、土壤理化性质及其相关关系,探讨不同林龄混交林土壤特征及微生物学特性,以期为华北落叶松林合理经营提供理论依据。研究结果表明:土壤有机碳、全氮、微生物量及微生物熵均随着土层深度的加深逐渐减小;土壤微生物量碳氮、有机碳、全氮含量均表现为随林龄增加而先减小后增加的趋势,且土壤碳氮比在25a混交林内显著低于其他两种林龄,土壤由"真菌型"向"细菌型"转变。随混交林林龄的增加,表层土壤微生物熵逐渐增大,土壤有机碳活性较大,碳库稳定性较差。相关分析表明,不同林龄的华北落叶松白桦混交林下,土壤微生物量碳氮含量与土壤有机碳、全氮、p H、微生物碳熵和氮熵均有极显著的相关关系。因此,土壤微生物可以敏感地指示土壤肥力的变化。

To study soil microbial biomass in Larch-Betula platylla mixed forests of different ages,this paper analyzed the content and correlation of soil microbial biomass carbon and nitrogen,soil physicochemical properties and the ratio of soil microbial carbon and nitrogen,aiming to explore the characteristics of soil and soil microorganisms.The results showed that soil organic carbon,total nitrogen,soil microbial biomass and soil microbial entropy gradually decreased with soil depth.All of them represented a trend of decreasing firstly and then increasing as forest ages increased,and soil turned from“fungal type”to“bacteria type”.The ratio of soil organic carbon and total nitrogen in the age of 25 was extremely lower than both of other two ages.In forest floor,soil microbial entropy was greater with the forest age increase,with the higher activities of soil organic carbon,and the instability of soil carbon pool.The correlation analysis showed that there was a significant relationship among soil microbial biomass carbon and nitrogen and soil organic carbon,total nitrogen,the value of pH,microbial entropy.Thus,soil microorganism presented the variation of the soil fertility as a sensitive indicator.