巨桉连栽对土壤微生物生物量和数量的影响

为探讨巨桉连栽对土壤微生物生物量和数量的影响,采用时空互换法,研究了马尾松(Pinus massoniana)林和不同连栽代次的巨桉(Eucalyptus grandis)人工林的微生物生物量、数量与土壤理化性质的关系。结果表明,巨桉一代林的土壤微生物生物量碳、生物量氮和土壤真菌、细菌数量与马尾松林的差异不显著,放线菌数量则显著增加。随巨桉连栽代次增加,土壤微生物生物量碳、生物量氮和土壤细菌、放线菌、真菌数量均递减。回归分析表明,土壤全磷能独立解释微生物生物量氮、细菌和真菌数量71.7%、86.1%和63.0%的变异,与总孔隙度共同解释微生物生物量碳87.9%的变异,与全氮共同解释放线菌数量89.6%的变异。可见,土壤全磷较大程度解释了微生物的变化。

Effect of Continuous Planting of Eucalyptus grandis on Biomass and Number of Soil Microbes

In order to understand the effect of continuous planting of Eucalyptus grandis on biomass and number of soil microbes, the relationships between soil microbial biomass, number of major microbial groups with soil physicochemical properties in Pinus massoniana forest and E. grandis plantations at different rotations were studied by using space-time interchange method. The results showed that the soil microbial biomass carbon, biomass nitrogen and number of bacteria and fungi in the first rotation plantations of E. grandis had not significant difference from those in P. massoniana forest, but the number of actinomycetes significantly increased. However, with the increasing rotation of Eucalyptus grandis continuous plantations, the soil microbial biomass carbon, biomass nitrogen and the number of bacteria, actinomycetes and fungi decreased. Stepwise regression analysis showed that soil total phosphorus could independently explain 71.7%, 86.1% and 63.0% variation of the microbial biomass nitrogen, the number of bacteria and fungi, respectively. Soil total phosphorus together with total porosity could explain 87.9% variation of microbial biomass carbon, and 89.6% variation of the number of actinomycetes together with total nitrogen. So, it could be concluded that soil total phosphorus well explained the variation of soil microbial characteristics in E. grandis plantations.