Identifying Soil Resource Pools within Forest Communities Using Eco-Geophysics.

Ecohydrological processes are important drivers of forest vegetation establishment and growth. Springtime snowmelt fate is partitioned by subsurface properties dictating soil moisture and nutrient storage capacities as well as rates of fluid transport. In many instances soil clay content (texture) is the dominant factor controlling these processes and as a result may in turn be well correlated with vegetation community structure. Geophysical techniques have been well established for locating geological features and resource deposits, but have not been widely tested as tools for determination of soil properties that drive ecohydrological processes. Recent work has demonstrated the utility of electromagnetic induction (EMI) mapping for correlating soil clay content with vegetation distribution in the Reynolds Mountain East watershed. We applied eco-geophysical techniques by coupling GPS-based EMI mapping with electrical resistance imaging (ERI) to uncover subsurface properties (i.e., texture and depth) impacting snowmelt fate and transport. In process of this exploration, important subsurface features were revealed regarding soil moisture storage that show correlation with vegetation structure. Soil electrical conductivity maps using EMI revealed significant differences in soil texture across aspen, conifer, sage and grass/forb communities. Electrical resistance imaging revealed detailed vertical features of the soil textural profile and apparent soil-bedrock interface. These provide detailed hydrologic information on the soil moisture reservoir capacity which is an important vegetation constraint in semi-arid climates. Geophysical techniques using electromagnetic and electrical methods, show great promise for ecohydrologic investigations.