Litter Decomposition of Spartina alterniflora and Juncus roemerianus: Implications of Climate Change in Salt Marshes

Decomposition of plant litter in salt marshes plays an important role in coastal trophodynamics, nutrient cycling, sediment trapping, and short-term carbon storage, all of which are likely to be affected by climate change and accelerated sea-level rise. Warmer temperatures, altered precipitation patterns, longer and more frequent inundation, and saltwater intrusion will all interact to affect decomposition of plant litter in a complex way. A combination of field experiments and model selection techniques was applied to study how these environmental factors affected litter decomposition of two dominant salt marsh species, Spartina alterniflora and Juncus roemerianus, along the northern Gulf of Mexico. The results from summer field experiments conducted between June and August of 2013 showed that S. alterniflora in the low marsh had higher litter losses (0.286 +/- 0.0883 g d(-1), mean standard deviation) and decomposition coefficients (0.0115 +/- 0.00416 d(-1)) than J. roemerianus in the midmarsh locations (0.0963 +/- 0.0480 g 0.00416 +/- 0.00223 d(-1)). Modeling results showed that the interaction between temperature and salinity significantly affected decomposition coefficients of both species positively during this experiment. This study suggests that accelerated leaf litter decomposition due to rising temperature and increased salinity will occur under climate change and sea-level rise, and this will potentially lead to important ecological consequences for salt marshes.