黄土高原沟壑区人工沙棘林生长年限对土壤微生物组成的影响

为了认识土壤微生物在不同生长年限沙棘林中的地位和作用，利用“平板培养法”和常规方法，研究了不同生长年限人工沙棘林土壤微生物三大类群组成和土壤养分的变化情况，并以系统聚类及主成分分析（PCA）等方法进行数据分析。土壤微生物总数量及三大类群数量以7 a 林最高（493．87×105 cfu?g －1干土），10 a 林（358．77×105 cfu?g －1干土）和15 a 林（321．69×105 cfu?g －1干土）最低且相互之间无显著性变化（P＜0．05）；土壤微生物三大类群中，土壤放线菌数量对 Shannon －Wiener 指数的大小变化起着较大作用；依据可培养微生物组成，4组样地可划分为3个类群，生长年限对土壤微生物组成的作用明显，且人工沙棘林生长年限超过10 a ，其土壤微生物数量已接近于撂荒地。土壤微生物组成与人工沙棘林生长年限关系密切且具有其独特的规律及变化原因。

Effects of different aged artificial seabuckthorn forests on soil microbial-composition in the gully region loess plateau, China

To further understand the status and effects of different aged artificial sea buckthorn forests on soil microbial-composition, three major groups of soil microorganisms were investigated by plate cultivation. Meanwhile, the data in the study were analyzed using the hierarchical cluster as well as the principal component analysis (PCA). The results showed that, for the total quantity of the soil microorganisms among all three major microbial groups, 7a forest had the highest, whereas 10 a and 15 a contained less and there was no significant difference between them. Additionally, the group of actinomycetes, though smaller in quantity, played a more important role in influencing the variations of Shannon-Wiener index. Four kinds of different aged sea buckthorn forests were classified into three classes according to the composition of culturable soil microorganisms through the analyses of hierarchical cluster and the principal component analysis (PCA). Forest age played extremely significant roles in affecting the soil micro-composition. Furthermore, in this study, the results also indicated that the microbial-composition in sea buckthorn forests more than 10 years old was similar to that in the abandon land. In conclusion, it was suggested that there was a particular rule and causes for the variations in soil microorganism composition under different aged sea buckthorn forests, which offered reference and theoretical basis to the sustainable development of economic vegetation in the gully region of loess plateau.