The relationship between variable hydroperiod, production allocation, and belowground organic turnover in forested wetlands
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Belowground processes in forested wetland ecosystems are exceptionally important, yet most attention seems to focus on surface flooding regimes and other aboveground features of these systems. Field studies in the Dismal Swamp and several manipulative experiments examined belowground dynamics in relation to a flood intensity gradient. Generally, more extensive flooding results in less production allocation belowground. Erroneous conclusions regarding wetland production are reached if aboveground parameters alone are considered. Root decomposition rates are slowest where the duration of soil saturation is the longest. Organic accumulation rates in wetlands are determined by the amount of production of particular biomass types (eg., leaves vs. roots) and the rate at which they decompose. Biomass allocation patterns seem to change in response to a flooding gradient. This represents a major implication for wetland ecosystem functions, as carbon allocation patterns determine the array of litter types that affect decomposition rates and thus nutrient availability. The hydroperiod data from the Dismal Swamp demonstrate the highly variable nature of flooding in forested wetlands, especially during the growing season. The data suggest that it is unwise to rely on hydroperiod as a direct criterion for identifying a jurisdictional wetland.
Key Wordsallocation belowground forested wetland hydrology hydroperiod production
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