Peatland Volume Mapping Over Resistive Substrates With Airborne Electromagnetic Technology

Despite the importance of peatlands as carbon reservoirs, a reliable methodology for the detection of peat volumes at regional scale is still missing. In this study we explore for the first time the use of airborne electromagnetic (AEM) to detect and quantify peat thickness and extension of two bogs located in Norway, where peat lays over resistive bedrock. Our results show that when calibrated using a small amount of field measurements, AEM can successfully detect peat volume even in less ideal conditions, that is, relatively resistive peat over resistive substrata. We expect the performance of AEM to increase significantly in presence of a conductive substratum without need of calibration with field data. The organic carbon content retrieved from field surveys and laboratory analyses combined with the 3‐D model of the peat extracted from AEM allowed us to quantify the total organic carbon of the selected bogs, hence assessing the carbon pool. Plain Language Summary Wetlands hide a secret. We may know them for their beauty and valuable ecological services, but the real treasure of these environments is hidden underground. It is the carbon pool that these ecosystems build every day, inch by inch, subtracting carbon dioxide from the atmosphere and storing it underground. This process forms a dark soil extremely rich in organic matter that we call “peat.” Peatlands around the world store almost the same amount of carbon that is present in the atmosphere. The problem is that, spoiling peat, the carbon is released as carbon dioxide and we have less carbon stored underground and more greenhouse gasses in atmosphere. The first step we should take in order to protect peatlands is to find effective methodologies to map them. In this study, we use an instrument carried by a helicopter that allows us to explore under the soil surface. We show for the first time that this technology, called airborne electromagnetics, can be used to quantify the peat stored underground in boreal peatlands. Thanks to this methodology, we can now map large areas and calculate the amount of carbon stored in peatlands, which is the first step toward implementing better conservation policies. Key Points Airborne electromagnetic can be successfully used to estimate peat thickness and extension even over resistive substrata The 3‐D geometry and volume of selected Norwegian bogs were determined The carbon pool is determined by combining the 3‐D peatland model with the soil organic carbon cont