LAUSR

AimsPlant roots control many important interactions in the wetland anoxic zone such as carbon deposition, gas exchange, and nutrient dynamics, yet few studies document the vertical depth distribution of fine roots which mediates these interactions.MethodsExcavated root systems of a wetland sedge and shrub were scanned. Utilizing Root System Analyzer, normalized root length per 5 cm depth interval were quantified for 10 samples of each species. Utilizing bootstrapping, root length per depth interval for each root class was fitted to a density distribution function and matched to water table depth.ResultsVertical root length distributions varied by root class, with shrub fine roots constrained to a narrow depth range. Between 1999 and 2010, the interface with the anoxic zone can vary by a factor of four between wet and dry years.ConclusionsCompared to estimates of root vertical distribution based on biomass, this study indicates a considerably higher portion of the fine roots occur in anoxic soil. Accurately quantifying the spatial distribution of the fine roots, root tips, and other sites associated with exudation is crucial for determining the strength of root-methanogen interactions.