库布齐沙地两种植被恢复类型根际土壤微生物群落功能多样性研究

为研究库布齐沙地生态恢复过程中不同植被恢复类型对土壤微生物群落功能多样性的影响,采用Biolog-ECO微平板检测法,对库布齐沙地自然恢复19年的油蒿群落、人工种植19年的中间锦鸡儿群落土壤微生物群落功能多样性进行研究。结果表明:1)土壤微生物群落利用全部碳源的代谢活性和土壤微生物功能多样性指数均表现为两种植被恢复类型显著高于流沙对照,其中,自然恢复的油蒿群落根际、非根际土壤分别高于人工种植的中间锦鸡儿群落根际和非根际土壤;2)随着植被恢复,从流沙对照土壤微生物以氨基酸类、胺类和芳香类为主要碳源,转为主要利用糖类、羧酸类、多聚物类碳源。不同植被恢复类型对碳源的利用不同,油蒿群落以糖类、羧酸类、多聚物类为主要利用碳源,中间锦鸡儿群落以羧酸类、氨基酸类和胺类为主要利用碳源;3)主成分分析表明,不同植被恢复类型土壤微生物碳源利用特征出现分异,在主成分分离中主要贡献者是糖类碳源;4)土壤氮素含量与土壤微生物群落功能多样性密切相关。冗余分析表明,土壤有机质、全氮、速效钾、速效氮、pH和全磷是土壤微生物群落利用碳源的主要控制因子。综合分析认为,植被恢复改变了沙地土壤微生物群落结构和功能多样性,自然恢复的油蒿群落更有利于增加利用多类碳源的微生物种群,在提高微生物利用碳源的整体代谢活性方面具有显著优势。

Rhizosphere microbial functional diversity affected by vegetation restoration in the Hobq Sand Land,Inner Mongolia,China

Soil microbial functional diversity is an important indicator of the condition and function of soil micro-bial communities and is also a useful indicator in the process of ecological restoration.We sought to study the effects of different vegetation restoration techniques on microbial functional diversity during ecological restora-tion in the Hobq Sand Land.Two types of vegetation restoration were compared;natural restoration of Arte-misia ordosica and reintroduction of Caragana intermedia ,which began in 1995,using a Biolog micro-plate technique with untreated sandy soil as the control.The results demonstrated that:1 )compared to untreated land,vegetation restoration resulted in increases in the rate of soil microbial carbon source utilization and com-munity metabolic diversity.Between the two restoration types,both soil microbial carbon source utilization rate and community metabolic diversity in the rhizosphere and non-rhizosphere soils were higher in sites re-stored with A.ordosica than in sites restored with C.intermedia.2)The carbon sources predominantly used by soil microbes in untreated soil were amino acids,amines,and phenolic acids;these were replaced by carbo-hydrates,carboxylic acids,and polymers as vegetation recovered;these differences were significant.3)Princi-pal component analysis demonstrated that there were differences in soil microbial metabolic activity among dif-ferent vegetation restoration systems,in particular,carbohydrates.4)Soil nitrogen (N)was strongly correla-ted with microbial functional diversity.Redundancy analysis (RDA)of microbial communities constrained by different soil factors showed that soil organic matter,total N,available K,available N,pH,and total P were important factors determining the rate of metabolism of carbon substrates.It was concluded that natural resto-ration of the A.ordosica community was better at fostering soil microbial communities capable of using differ-ent carbon sources with enhanced microbial metabolic activity than reintroduction of the C.intermedia and the untreated approach.