CARBON STORAGE AND NITROUS OXIDE AND METHANE EMISSIONS IN MANAGED AND UNMANAGED URBAN LAWNS AND FORESTS

Urban lawns may be beneficial for the uptake of organic carbon (OC) to mitigate excess carbon dioxide in the atmosphere. However, lawn maintenance may also contribute to atmospheric greenhouse gas emissions. This study looks at OC stocks and GHG flux rates from urban forest soils and both managed and unmanaged urban lawns in Cincinnati, OH to evaluate and quantify the amount of carbon that is being sequestered over time, and to measure the emission and uptake of GHG in the different kinds of soils in relation to overall emissions of GHG. OC stocks were measured by collecting transects from lawns of varying ages to develop a chronosequence to determine the amount that the soils can store over time. Both forest soils and lawns can sequester CO₂, but it appears that unmanaged and forest soils have higher carbon stocks than managed lawns, and the ability of a managed lawn to sequester OC has a cap between 20 to 30 years. Flux data was collected following USDA-ARS chamber-based protocols, using static chambers placed randomly at sites. It was hypothesized that the urban lawns, both managed and unmanaged, would have a lessened ability to uptake GHG relative to the urban forest soil. Although preliminary data upholds this hypothesis, further data are needed to study the relationship between lawn maintenance and the inherent capacity of a lawn to uptake GHG.