连栽杨树林对土壤微生物的影响

为研究杨树长期栽植对土壤微生物造成的影响,对江苏省宿迁市泗洪县陈圩4块杨树林地土壤进行调查.使用常规土壤化学分析手段分析了样品的主要理化性质,分别测定了样品的微生物生物量,并对微生物三大菌群以及与氮元素转化密切相关的几种微生物类群进行了计数.实验结果表明:长期栽植杨树会使林地土壤的pH逐渐升高,栽植杨树14 a后林地土壤pH约比对照土壤上升1.5;林地土壤的养分元素氮、磷含量随着林龄增长而降低,而有机质的含量随着林龄增长而增加,但是明显低于对照.土壤微生物中真菌的数量随着栽植时间而逐渐下降,而细菌总数、放线菌总数,以及微生物生物量表现出与土壤有机质含量相一致的变化规律.对参与氮素循环的土壤微生物类群进行计数,发现反硝化细菌的数量随着林龄的增大而明显增加,而硝化细菌(铵氧化细菌与硝酸细菌)的数量则有所下降.

Effects of Replanting Poplar on Soil Microorganisms

To investigate the effects of replanting poplar on soil microorganism, four soil samples were collected from Chenwei poplar forestry center of Sihong county, Jiangsu Province. The physical and chemical properties of soil were analyzed and the concerned microorganisms in them were counted. The results showed that long-term plantating of poplar increase of pH as high as 1. 5 after 14 years of plantation. The contents of N, P in soil decreased as years advanced while the contents of organic matter increased gradually. The amount of bacteria, actinomycete as well as the microbial biomass changed in accordance with that of the organic matter. On the other hand, the amount of fungi improved along the expansion of time. Concerning microbe involved in the cycling of N, the amount of denitrate bacteria was demonstrated to drop obviously as the time of planting advanced, while that of nitrobacteria increased to some extent.