Hydrologic Modeling of Alaskan Bogs: A Synthesis of a Soil Respiration Study in a Coastal Temperate Rainforest
This report examines some preliminary results of a study done in the North American Pacific coastal temperate rainforest (NCTR) and outlines a hydrologic model created to address some critical data gaps. The NCTR runs from northern California to south-central Alaska and is characterized by a cool and perennially humid climate. Recent studies have found that the NCTR contains a globally significant stock of soil organic carbon that is sensitive to soil moisture and temperature changes. While work has been done to investigate the impacts on CO2 export from soils, little has been done to examine other greenhouse gases. This study aims to fill these information gaps and examine methane and nitrous oxide soil emissions, in conjunction with additional carbon dioxide fluxes. We measured the response of the greenhouse gas fluxes to soil moisture and temperature across three systems along a hydrologic gradient: fen, forested wetland, and upland. We found negligible nitrous oxide levels and comparable carbon dioxide levels to previous studies. However, we found large spikes of methane (up to about 2.0 μmoles m-2 s-1) from one fen in particular. This same fen exhibited a much higher water table than we anticipated, causing our soil water measuring devices to reach their maximum value early in data collection. This resulted in major data gaps for soil water table values, which have been shown to be the major driver of methane emissions in waterlogged systems. Therefore, I created a hydrologic model of the system so as to simulate the hydrology and fill in the data gaps that are critical to our analysis of the NCTR greenhouse gas study.
Hydrologic Model; Soil greenhouse gas flux
articledissertation or thesis