海南岛桉树人工林土壤微生物功能多样性特征

Soil microbial functional diversity of Eucalyptus plantation in Hainan Island

运用Biolog-ECO微平板技术,对海南岛4龄桉树人工林不同土层深度的土壤微生物群落功能多样性的动态变化进行分析。结果表明：随着培养时间的延长,土壤微生物平均AWCD逐渐增大,代谢活性逐渐增强,300h时AWCD值下层土〉中层土〉上层土;不同土层微生物对胺类碳源利用率最高,酚酸类、氨基酸类和多聚物类次之,碳水化合物和羧酸类最低;随着土层深度增加Shannon多样性指数（H）逐渐增大,20~30cmMc Intosh丰富度指数（U）和Simpson优势度指数（D）明显高于其他土层,而Mc Intosh均匀度指数（E）又显著较低,0~10cm土层的Shannon多样性指数（H）、Simpson优势度指数（D）和Mc Intosh丰富度指数（U）均较低,即桉树人工林表层土壤的微生物活性受到不同程度的抑制;主成分分析（PCA）表明,在31种碳源中提取的2个主成分因子分别可以解释所有变量方差的41.65%和32.51%,对PC1和PC2起分异作用的主要碳源为碳水化合物、氨基酸及其衍生物类和胺类;土壤微生物功能多样性还受土壤性状的综合调控,尤其与土壤有机质、土壤容重和土壤碱解氮含量相关性最明显。

As one of the most important components in soil ecosystem,soil microbes have irreplaceable effects on nutrient and energy cycling. In the research,the changes of functional diversity of soil microbial community were analyzed by using the method of Biolog-ECO microplate culture in different soil depths of 4-year Eucalyptus plantation in western Hainan Island. The results showed that the average well color development （AWCD） increased with incubation time,and there were significant differences among different soil layers,varying from 0.85,0.97 and 1.00（cultured for 300 hours） for 0-10 cm,10-20 cm and 20-30 cm soil layer. The microbial communities in different soil layers had similar carbon sources utilization mode; it found that amine was the highest availability of carbon sources,followed by Phenolic acids,amino acids,polymer,and carbohydrates,and carboxylic acids had the lowest utilization rate. However,the carbon utilization efficiency increased with the soil depth,the values of Shannon-Wiener index （H）,Simpson index （D） and Mc Intosh index （U） all increased with layer increasing; itsuggested that soil microbial activity in the surface layer of Eucalyptus plantation was restrained in different degrees. Principal component analysis（ PCA） indicated that 2 principal components possessed 41.65% and 32.51% explained variance to carbon sources. Carbohydrates,amino acids and amine were the 3 main carbon sources separating the 2 principal component factors. The significant relationships were observed between the metabolic diversity of microbial communities and soil physical and chemical properties,through correlation analysis,soil organic carbon,soil bulk density and soil available nitrogen were important factors determining the rate of metabolism of carbon substrates in soil.