Soil organic matter stability and microbial community in relation to different plant cover: A focus on forests characterizing Mediterranean area

In this study, soil organic matter (SOM), as well as the structure and function of soil microbial communities in three forest systems (holm oak, black pine and beech) widely distributed in the Mediterranean area, were analyzed to assess the effects of different canopies on microbial community. Fourier transform infrared (FTIR) spectroscopy, combined with Thermal analyses, was used to characterize SOM, in order to obtain information on its quality and stability. Soil microbial communities were analyzed through the phospholipid fatty acid (PLFA) profile, ergosterol, hydrolase, laccase and peroxidase activities, fungal and bacterial growth. Soil under pine and beech contained more recalcitrant SOM, in respect to the soil under holm oak, characterized by more labile SOM. The PLFA analysis showed a different structure of the edaphic microbial community of the three forests. Soils under pine was characterized by the greatest abundance of fungal biomass and high peroxidase activity likely in relation to the presence in this soil of more recalcitrant compounds, mainly decomposed by fungi. Overall, pine and beech forests represent important carbon sinks with larger amounts of recalcitrant organic matter in their soils.