The standing dead phase is an important stage in the decomposition of emergent vegetation
in marsh wetlands, yet few studies have examined how intrinsic litter traits
constrain rates of standing litter decomposition or fungal colonization across plant
tissue types or species. To address broad constraints on the decomposition of standing
dead litter, we conducted a systematic survey of emergent standing dead decomposition
studies that measured decay rates and/or fungal biomass, and litter % lignin,
carbon:nitrogen (C:N) and/or carbon:phosphorus (C:P). Across 52 datasets, litter
of low C:N and C:P ratios exhibited increased decomposition rates (r = −0.737 and
−0.645, respectively), whereas % lignin was not significantly correlated with decomposition
rates (r = 0.149). Mixed-effects models for litter decomposition rates indicated
significant effects of litter molar C:N and C:N + lignin as an additive model,
with the former providing marginally better support. Litter % lignin, however, was
strongly negatively correlated with fungal biomass (r = −0.669), indicating greater
fungal colonization of low-lignin litter, and not correlated with C:N (r = −0.337) and
C:P (r = −0.456) ratios. The best-supported model predicting fungal biomass was litter
molar C:N, with the C:N + lignin additive model also showing significant effects.
Fungal carbon-use efficiency (CUE) also had a strong negative correlation with % lignin
(r = −0.604), molar C:N (r = −0.323) and C:P (r = −0.632) across datasets. Our
study demonstrates the constraining effects that litter stoichiometry and % lignin elicit
on decomposition of standing dead litter and fungal colonization, respectively. These
findings improve our understanding of biogeochemical cycling and prediction of the
fates of C and nutrients in wetlands.

Literature data collation. See manuscript for details.

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