Effects of Litter Evenness, Nitrogen Enrichment and Temperature on Short-Term Litter Decomposition in Freshwater Marshes of Northeast China

Abstract

Knowledge about the effects of global change factors on litter decomposition is critical for accurate prediction of future carbon (C) and nutrient cycles in terrestrial ecosystems. Here, we collected Deyeuxia angustifolia and Carex lasiocarpa litters from freshwater marshes in Northeast China, and conducted an incubation study to examine the effects of nitrogen (N) enrichment (0 and 25 mg N g−1 litter), temperature (5, 15, and 25 °C), and litter evenness on litter mixing effect and decomposition. Non-additive effects were more common than additive effects during decomposition of litter mixtures, and synergistic effect was detected in two thirds of the litter mixtures. Moreover, litter mixing effects on decomposition varied with N enrichment, incubation temperature, and litter evenness. Both increased proportions of D. angustifolia in litter assemblages and elevated temperature generally accelerated litter decomposition. However, N enrichment slowed litter decomposition at 5 and 15 °C, but had positive or neutral effect at 25 °C. Our results highlight the importance of the interactive effects of N enrichment, temperature, and plant community structure on litter mixing effects during decomposition, and suggest that accelerated litter decomposition induced by climate warming and altered vegetation community would be modulated by N enrichment in freshwater marshes of Northeast China.