See more from this Session: Soil Carbon Dynamics in Forest Soils
The primary measure of system effectiveness has been the ability of the system to sequester carbon, measured by assessing survival and growth response of plants within the CCWESTRS project. Additionally, site soils and subsurface materials are being evaluated for their effectiveness at treating the irrigation water for various pollutants. As early as three years after the initial field planting, American sycamore biomass had increased significantly as a function of greater mulch depth and total irrigation. Sweet gums have not exhibited a similar response. Below-ground carbon stocks decreased initially primarily due to the conversion from grasses and forbs to trees, but this trend has slowly reversed. The greatest changes in soil chemistry across the site have been due to the use of FGD gypsum mulch and ash pond irrigation water which has resulted in higher levels of calcium and sulfur with depth. Although boron levels in the irrigation water have reached concentrations as high as 8 mg/l and some leaf tissue concentrations have exceeded 250 ppm, very little toxicity symptoms have appeared in either tree species.