Response of litter carbon, nitrogen and phosphorus to simulated leaching

Abstract

Leaf litter is the main input of organic carbon and nutrients to terrestrial and freshwater ecosystems. The decomposition of leaf litter is crucial to the regulation of ecosystem carbon and nutrient dynamics. Abiotic leaching, i.e., water extraction of soluble elements from litter, is an important mechanism for release of carbon and nutrients from litter, providing easily accessible energy and nutrient source for microbes. However, relatively few studies have quantified the response of different litter species to leaching. In addition, it remains largely unclear that whether different elements in litter differ in solubility and whether the response of elements to leaching can be predicted by initial litter traits. In order to fill these knowledge gaps, recently senesced leaf litter of 15 subtropical broad-leaved tree species were leached in de-ionized water over 6 h in lab. Litter mass loss, carbon, nitrogen and phosphorus release after leaching were quantified. In addition, for each litter species, we measured 11 litter traits, including leaf thickness and toughness, maximum and standardized water holding capacity, contents of carbon, nitrogen, phosphorus, lignin and cellulose, specific leaf area and leaf dry matter content, and tested the influence of these litter traits on elements release patterns. After leaching, there were significant variation in litter mass loss, carbon, nitrogen and phosphorus release among different litter species ( P P P <0.001). The response of elements to leaching could be predicted by initial litter traits. The maximum water holding capacity of litter was the best predictor of carbon release, while the specific leaf area was the best predictor for both nitrogen and phosphorus release after leaching. We concluded that, despite the short duration of leaching, a considerable amount of nutrient release can occur, which influence litter chemistry and then probably affect subsequent microbial decomposition process. However, elements in litter have differential solubility so that different elements cannot be treated equally. Like microbe-mediated decomposition, trait-based approach can be used to predict the response of litter to leaching.