Stoichiometry of carbon, nitrogen, and phosphorus released from the leaf litter of various temperate tree species

Abstract

Dissolved organic matter and inorganic nutrients released from forest leaf litter through leaching are the important energy and nutrient sources that support the production of aquatic food webs. Litter leachate-derived dissolved organic carbon (DOC) is a critical energy source for aquatic heterotrophic microbes, and inorganic nitrogen and phosphorus can enhance primary production. In this study, we experimentally measured the release efficiencies and amounts of dissolved organic DOC, total dissolved nitrogen (TDN) and total dissolved phosphorus (TDP) of the leaf litter from 11 temperate tree species by soaking the leaf litter in water for 28 days. We found that the maximal release efficiency (% of element released per estimated mass of the element) was the highest for P and lowest for N. These efficiencies were species-specific. Additionally, the DOC:TDP and TDN:TDP ratios varied among the leachates of different leaf litter species and were considerably lower than the C:P and N:P ratios in leaf litter biomass; the DOC:TDN ratio was higher than the C:N ratio in leaf litter biomass. These results suggested that the ratios of organic carbon to nutrients dissolved into water cannot be fully elucidated using the elemental ratios of leaf litter mass. Based on these findings, we concluded that changes in the vegetations with different leaf litter stoichiometry can alter the relative importance of detrital and grazing food chains in aquatic ecosystems.