Soil microbial community structure of monoculture and mixed plantation stands of native tree species in south subtropical China

The effects of three plantation stands,Erythrophleum fordii( EF),Pinus massoniana( PM),and their mixed plantation( MP),on soil microbial biomass and microbial community structure in south subtropical China were studied by the method of phospholipid fatty acids( PLFAs) analysis. The results showed that the amounts of microbial total PLFAs and PLFAs of each microbial group in these three plantation stand soils were significantly higher in dry season than in rainy season. In dry season,the amounts of microbial total PLFAs,bacteria PLFAs,fungi PLFAs,and actinomycetes PLFAs were the highest in the PM soil,moderate in the MP soil,and the lowest in the EF soil. But in rainy season,the amounts of microbial total PLFAs,bacteria PLFAs,fungi PLFAs,and arbuscular mycorrhizal fungi( AMF) PLFAs in the EF soil were higher than in the MP soil,and were significantly higher than in the PM soil. Principal component analysis( PCA) indicated that the variations in soil microbial community structure composition were affected by both plantation types and seasons. Redundancy analysis( RDA) of soil microbial community structure and environmental factors showed that soil temperature and moisture,pH,total nitrogen content,and ammonium nitrogen content had significant correlations with PLFA signatures. In addition,the ratio of fungi PLFAs to bacteria PLFAs in the MP soil was the highest among the three stand soils within the whole year,indicating that mixed plantation stands could facilitate the stability of the soil ecosystem.