Title: Greenhouse Gas Emissions in Contrasting Soil Moisture Regimes from an Ozark Highlands Tallgrass Prairie

Authors: Will Dockery, Tyler Buchanan, Diego Della Lunga, and Kristofor R. Brye

An uncommon and distinct biophysical transition zone from the relatively dry grasslands of western North America to the humid forests of the southeast is the Ozark Highlands ecoregion. Before the 20th century a sizable portion of the Highlands was native tallgrass prairie interspersed with oak (Quecus spp.) savannah. However, most of the tallgrass prairies in the region have now been converted into pasture, upland row crops, and urban areas. Quantifying greenhouse gas (GHG) emissions, namely carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), by natural, undisturbed ecosystems is critical to understanding atmospheric warming and climate-change implications. To date, most studies on prairie soils and GHG production have been limited to the north and central Great Plains and only measured CO₂ fluxes. The objective of this study is to simultaneously evaluate CO₂, CH₄, and N₂O emissions in an aquic and udic soil moisture regime in the intermound position in a native tallgrass prairie remnant in the Ozark Highlands region of northwest Arkansas. Gas fluxes were measured weekly throughout Summer 2024 (mid-May through September) using a field-portable, GHG analyzer system. Gas emissions varied between udic and aquic soil moisture conditions over time. Greenhouse gas emissions from native tallgrass prairie remnants can provide insight into expected baseline GHG emissions and potentially provide a target for agricultural production and prairie restoration activities.