Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/10/2015
Publication Date: N/A
Technical Abstract: Basic information on the ecological understanding and the responses of systems to water regime change is essential for maintaining ecosystems environmental integrity and productivity. Flooding of formerly drained areas is common practice in wetland restoration. Such practice could profoundly affect microbial and chemical processes underlying nutrient transformations, especially pathways for soil organic carbon (SOC) formation and accumulation. There is a major need to understand the historical condition and chemical/biological functions of the ecosystems following a conversion of wetlands to agricultural functions. To better understand SOC dynamics during reconversion of former beef cattle pastures to wetland, soil core samples were collected from both systems in the southeast area of Florida, United States of America. This region has a long history of beef cattle production on formerly wetland soils. Soil core (0-20; 20-40; 40-60 and 60-100 centimeter(cm) samples were collected from 11 locations in the beef cattle pasture and four locations in the adjoining natural wetland with a hydraulic sinker drill sampler. The total SOC in the upper meter of soil under a wet condition (164 milligram per kilogram (mg/kg) was significantly higher than the total SOC in soil under dry condition (45 mg/kg). Over 50 years, we found that draining these natural wetlands to sustain grazed pastures resulted in very pronounced reduction of SOC from 180.1 to 5.4 gram per kilogram. The concentration of SOC was reduced by 96% over the periods of land use conversion. It appeared that conversion of wetland was proceeding toward a soil condition/composition similar to that of mineral soils. The concentration of SOC was seven-fold higher in wet condition than in dry condition in the surface soil, but there were no differences below the 20-cm soil depth. Concentrations of SOC for both the wet and dry conditions generally decreased with soil depth. These results are important in establishing baseline information on soil properties in pasture and wetland prior to restoring and reconverting pasture back to wetland conditions. The results further suggest that changes in SOC due to changing land use and hydrologic conditions could provide long lasting information affecting ecosystem productivity.