A Global Synthesis Reveals Litter Stoichiometry and Lignin Constrain Fungal Colonization and Decomposition Across Standing Dead Macrophytes

The standing dead phase is an important stage of decomposition of emergent vegetation in wetlands, yet few studies have examined how intrinsic litter traits constrain standing dead decomposition or fungal colonization across plant tissue types or species. In addition to previous decomposition studies conducted by my research group, in which I quantified C:N, C:P, and % lignin, I conducted a global survey of emergent standing dead decomposition studies that measured decay rates and/or fungal biomass, and carbon:nitrogen (C:N), carbon:phosphorus (C:P), and/or % lignin. Across 49 datasets, low C:N (r = -0.728, Pr = -0.645, Pr = 0.129, P = 0.520) was weakly correlated to decomposition rates. Mixed-effects models indicated a C:N + lignin additive model (AICc = 53.62, P \u3c 0.001) provides the best-fit based on Akaike Information Criteria (AICC). Low % lignin (r = -0.777, P = 0.001), however, was strongly negatively correlated with fungal biomass, indicating greater fungal colonization of low-lignin litter, and weakly correlated with C:N (r = -0.076, P = 0.730) and C:P (r = -0.238, P = 0.326) ratios. The AICc best-fit is only % lignin (AICc = 38.10, P \u3c 0.001) based on the mixed-effects model. My study shows the constraining effect litter stoichiometry and % lignin have on fungal colonization and decomposition. This study improves understanding of global biogeochemical cycling and prediction of the fates of C and nutrients in standing dead wetland vegetation