Soil microbial community composition in four nothotsuga longibracteata forests in Southern China

Abstract

Soil microbial communities play a vital role in soil carbon and carbon sequestration in forest ecosystems. In this study, soils were sampled in Tianbaoyan National Nature Reserve in southeastern China from four Nothotsuga longibracteata forests, including a pure N. longibracteata forest (NF), N. longibracteata + hardwood mixed forest (NHF), N. longibracteata + Rhododendron simiarum mixed forest (NRF), and N. longibracteata + Phyllostachys pubescens mixed forest (NPF). Our objective was to precisely quantify soil physicochemical properties, microbial biomass, microbial communities, and to evaluate their interrelationships. We used biochemical measurements, a fumigation-extraction method, and phospholipid fatty acid (PLFA) analysis method to show that – except for pH and soil bulk density (SBD) – soil physicochemical properties differed markedly among the forest types. Microbial biomass carbon (MBC) and nitrogen (MBN) were highest in NHF soils, while the ratio of microbial biomass carbon to nitrogen (MBC:MBN) was highest in NRF and NPF soils. Moreover, the microbial communities of the four forest types exhibited distinct profiles: the highest total PLFA content and content of Gram-positive bacteria (Gram(+)), Gram-negative bacteria(Gram(-)), and fungi were found in NRF. Additionally, NHF soil exhibited the highest actinomycetes content, while the highest protozoal content was found in NF soil. The analysis of individual PLFAs using principal component analysis (PCA) demonstrated a clear association of distinct soil PFLA characteristics for each forest type. In conclusion, the soil microbial community structure can be significantly influenced by changes in soil organic carbon (SOC) and MBN. Comparing soil microbial properties in different N. longibracteata forests can help us understand the influence of forest types on the structure of microbiota within a system.