| The accumulation of the characteristic organic soils of the Upper St. Johns River Basin (USJRB) has taken several thousand years. The stability of these soils is highly dependent on hydrology as their formation is due to the historically extended hydroperiod of the USJRB floodplain wetlands. In some regions of the USJRB, the hydrology of the floodplain has been dramatically altered, resulting in substantial loss of organic soil. Knowledge of the critical water depth at which accelerated soil loss occurs is needed to refine estimates of marsh water levels which are protective of the soils of the region. The main goal of this research was to determine the minimum water levels in wetlands needed to prevent net loss of organic soils that eventually leads to subsidence of soils in the Blue Cypress Marsh (BCM) of USRB. This was achieved by investigating the effect of water drawdown on soils with different vegetation type, temperature and nutrient levels. The effect was determined by measuring microbial activities such as aerobic and anaerobic respiration, CH4 production, phenol oxidase activity and β glucosidase enzyme activities. |
