SSHCZO -- Soil Gas, Soil Moisture -- Garner Run and Shale Hills -- (2015-2016)

Shale and sandstone are the most common lithologies of the forested ridges throughout the Appalachian Mountains. The overall goal of this thesis was to determine whether these two rock types impart distinct biogeochemical properties to soils and plants. The effects of rock type (lithology) on soil gas concentration, nutrient concentration and nutrient limitation were studied in the Ridge and Valley province of central Pennsylvania. To increase understanding of lithological controls on soil gases (Chapter 1), we monitored the depth distribution of soil CO2 and O2 concentrations in central Pennsylvania in two watersheds on different lithologies. We deployed gas monitoring instrumentation on two catena transects that included four topographical positions, one located on sandstone and the other on shale. As expected, with increasing soil depth O2 concentrations decreased while pCO2 increased. CO2 and O2 concentrations varied more with topographical position than with lithology, as the valley floor positions in both catenas had the highest pCO2 for a given depth. Both manual sampling from gas access tubes throughout the soil profile and continuous sampling by buried sensors documented these patterns.