Influence of Water Levels on Subsidence of Organic Soils in the Upper St. Johns River Basin

摘要

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 Upper St. Johns River Basin (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 Beta glucosidase enzyme activities. The objectives of this study were to: Review current extent of literature on the subject of soil subsidence with special focus on organic soils; Determine relative proportion of labile, moderately labile, and refractory pools in soils of BCM; Determine soil organic matter loss rates as a function of water level relative to soil surface; Determine the influence of inundation frequency on soil organic matter decomposition; Determine the influence of dominant vegetation type, temperature, and soil nutrient levels on soil organic matter decomposition.