**5. Wetlands and hydric soils in the study area**

We define wetlands as soilscapes transitional between terrestrial and aquatic systems that support hydrophytes and possess an undrained substratum having anoxic conditions, typically having a water table for some portion of the time when the soil temperature is above biologic zero. In our study area, a large-scale drainage management system has been implemented to produce agriculture lands; however, the ancestral wetlands would have been classified as southern deepwater swamps and riparian forested wetlands [4]. Hydric soils are defined as "soil that is saturated, flooded or ponded long enough during the growing season to develop anaerobic conditions in the upper part" [5]. Prolonged anaerobic conditions promote selected biogeochemical soil processes that modify the soil morphology, such as (i) organic matter accumulation, (ii) iron and manganese oxyhydroxide transformations/depletions/accumulations, (iii) sulfate-sulfide transitions, nitrogen transformations, and (iv) biogeochemical nutrient cycle alterations. These indicators are used to delineate hydric soils; however, in the USA the indicator criteria may vary among the major land resource areas. Wetland delineation in the USA is based on the presence of hydric soils, the local hydrology, and wetland indicator plants.
