Carbon metabolism of soil microbial communities of restored forests in Southern China

The structure and dynamics of carbon metabolic process of the soil microbial community in restored forests were dependent on the methods employed in reforestation and subsequent management. To find an appropriate method to restore degraded forests and to assess the ecological benefits of restorations, we studied community level physiological profiles of soil microbial communities in forests in Southern China that were restored by three different methods. Community level physiological profiles of soil microbial communities in restored introduced slash pine (Pinus elliottii) plantation, restored native Masson pine (Pinus massoniana) plantation, and natural secondary forest in Southern China were studied based on outcomes of the Biolog(TM) Ecoplates incubation. For each type of restored forest, 15 experimental plots were randomly selected in Southern China. In each plot, three composite samples of 0 to 10 cm depth were obtained from three subplots for the analyses. It was found that the soil microbial communities of three types of restored forests were capable of metabolizing all 31 preselected carbon substrates on Biolog(TM) Ecoplates. However, the soil microbial community of the natural secondary forest was more diverse in structure of carbon metabolism, and more efficient in utilizing the carbon substrates than those of the Masson pine and slash pine plantations that had to acclimate and adopt different biochemical pathways to metabolize some of the carbon substrates. Soil available N content, moisture content, organic C content, microbial biomass C content, pH, clay content, and Shannon-Wiener diversity index of tree layer were factors contributing to the carbon source utilization structure of the soil microbial communities for the three types of restored forests. The soil microbial communities of all three types of restored forests would provide the same ecological services in metabolizing carbon sources in the forest soils. The microbial community of the natural secondary forest was consistently more efficient in carbon utilization than those of the Masson pine and slash pine plantation and often the Masson pine plantations were more efficient than that of the slash pine plantations. The natural secondary forest had a more diverse and stable soil microbial ecosystem and would be more adaptable to and respond more rapidly to environmental changes.