Nitrogen Cycling in Forest Floors – Do We Really Understand It?.

Foliar litter has long been accepted as an important source of nutrients in forest ecosystems. But is it really this simple? Decomposition of foliar litter in forests progresses within a matrix of carbon pools - annual fresh litter fall, old leaf litter, roots, root exudates, and downed wood. Within this carbon-rich matrix, there seems little opportunity at least for nitrogen to become ‘released’ from litter and plant-available. Instead, litter N may be rapidly re-immobilized into microbial biomass using another pool of carbon. In fact, nitrogen may be locked in a re-immobilization cycle for as long as adequate carbon sources are present. Literature and actual data from pine and hardwood forests are used to show that the fate of nitrogen released from decomposing foliar litter has not been adequately accounted for in litter decomposition studies, and the term nitrogen release may be misleading. The results suggest that we may have to rethink how we view and describe nitrogen cycling in forest floors.