黄土丘陵区人工林土壤微生物PLFA标记多样性分析

Soil microbial community structure and functional diversity in typical plantations marked by PLFA in hilly loess region

为研究不同植被下土壤微生物群落结构多样性的差异,采用磷脂脂肪酸(PLFA)生物标记法,对山西吉县黄土丘陵区典型人工林刺槐、油松以及荒草地的土壤微生物群落结构多样性进行分析研究。结果表明:不同植被下土壤微生物PLFA标记含量存在显著差异,刺槐人工林的土壤微生物PLFA总量最大,细菌、真菌、放线菌的PLFA含量均大于油松人工林和荒草地;细菌PLFA含量在3种样地中的差异显著;2种人工林的真菌PLFA含量接近,而与荒草地差异显著,与荒草地相比,人工林的种植可明显提高土壤中真菌的比例;革兰氏阳性菌与革兰氏阴性菌呈现相同的变化趋势,油松人工林与荒草地2种菌群的PLFA含量接近,而与刺槐人工林差异显著。通过相关性分析发现,不同植被下土壤细菌、真菌、革兰氏阳性菌与革兰氏阴性菌各总PLFA与土壤养分因子之间密切相关;不同植被下土壤微生物群落多样性差异显著,刺槐人工林更为丰富,且各个菌群分布更为均匀,油松人工林土壤的微生物群落多样性及菌群分布均匀度与刺槐人工林土壤较为接近,荒草地土壤微生物群落多样性和均匀程度较2种人工林明显偏低。因此从微生物群落结构多样性的角度看,人工林的种植能够明显改善微生物群落结构,改善土壤质量;刺槐人工林是黄土丘陵区人工植被恢复的较好选择。

This study was aimed to discover the effects of different types of plantations on soil microbial community structure and functional diversity in hilly loess region. The study area is located in Jixian County, Shanxi Province of northern China. Two typical plantations （Robinia pseudoacacia and Pinus tabuliformis） were chosen and a grassland was set as control. Soil samples in the vertical layers （0 -20 cm） were collected in August 2014, and soil microbial community structure was analyzed by phospholipid fatty acid （PLFA） analytical method. Results showed that the PLFA amounts of soil bacteria, fungi, actinomyces and Gram negative bacteria and Gram positive bacteria under the Robinia pseudoacacia plantation were all the highest in the three kinds of sample plots. Biomass of bacteria in three plots was significantly different, while that of fungi was roughly the same in the two plantations and significantly different with the grassland. Plantation improved the proportion of fungi. The phospholipid fatty acid structure of the two typical plantations was significantly different with the grassland. The correlation analysis showed that the amounts of the PLFAs were closely correlated to the soil fertility factors. Microbial community structure was correlated to plants： functional diversity was higher under the Robinia pseudoacacia plantation, followed by that under Pinus tabuliformis plantation, and grassland was theleast. Therefore, for the microbial community, the two typical plantations can improve the microbial community structure and the soil quality as well, and Robinia pseudoacacia plantation was better.