Including Microbial Processes is Important for Modelling Carbon and Nitrogen Dynamics During Wood Decay

Dead wood plays a potentially underappreciated role cycling nutrients through temperate and boreal forests, especially over the course of forest succession. The decay of carbon-rich, nitrogen-poor dead wood is primarily carried out by fungal and bacterial communities. This microbial community typically has a low carbon to nitrogen ratio (C:N ~10), when compared to coarse woody litter (250-500+), creating a potential stoichiometric imbalance and high demand for N. The rate at which N is released from dead wood and the fraction of woody carbon that is lost to respiration is strongly tied to microbial efficiency. Despite the strong microbial influence on carbon and nitrogen dynamics during wood decomposition, many ecosystem models still lack microbial stoichiometric controls on wood decay. Here we developed a model of wood decay to assess the influence of various parameters and mechanisms on carbon and nitrogen fluxes from dead wood. We applied this model to a forested watershed in the northeastern United States (Hubbard Brook Experimental Forest) and found that including microbial stoichiometric controls on wood decay reduced the quantity of nitrogen immobilized in dead wood pools and drastically reduced the fraction of carbon routed to microbial biomass and long-term soil organic matter pools.