The Hidden Role of Forest Tree Species in Driving Soil Organic Carbon Dynamics

The role of soil organic carbon (SOC) dynamics in forest carbon (C) balance has been widely recognized. The processes that mediate the relationships between forest tree species composition and the formation, turnover, and stabilization of SOC are not sufficiently understood. This paper aimed to compile the state of knowledge on the involvement of tree species composition in the regulation of SOC dynamics through litter quality, root properties, root exudates, microbial-mediated processes, and soil mineral interactions. A greater emphasis is given to the role of the SOC pool subdivision into active (labile) and passive (non-labile) fractions. These fractions turn over at a significantly different rate and have also been proven to be considerably different in terms of long-term stability. The properties of the trees and soil in the rhizosphere influence the rate of short-term and chemical conversion of plant material into the persistent or passive fraction of soil C through the mediating process of microorganisms. Evidence confirmed that the functional interactions between the mix of tree species increase the rate of SOC stabilization through an increase in the rate of active to passive fraction transition. This synthesis presents a trait-based approach for considering and addressing the dynamics of SOC in the environment.