Detecting Diapirs in the Frost Boils of a High Arctic Polar Desert.

Diapirs are areas of uplifted parent material above the permafrost table that are associated with patterned ground such as frost boils. These diapirs are overlain with a Bhy soil horizon enriched in soil organic carbon (SOC) that may provide important resources for plants growing on the surface. Since only certain plant species are likely able to access the resources, the presence of diapirs may influence species richness and composition of the aboveground and belowground plant community. Deep rooting vascular plant species such as Saxifraga oppositifolia, Salix arctica, and Papaver radicum that are found in the frost boil margins may be accessing the enhanced moisture and nutrients of diapirs. For these reasons, subsurface diapirs may be a keystone feature in polar deserts, and determining their prevalence on the landscape will increase our understanding of how important diapirs are for sustaining polar desert plant communities. We hypothesize that diapirs occur in the frost boils of granitic polar deserts and the presence of deep rooting vascular species on the Arctic desert landscape may indicate the presence of a Bhy horizon overlaid on a diapir.

We used a field-portable near-infrared/visible (NIR/VIS) range spectrometer to detect SOC, indicative of the diapir Bhy horizon, in the subsurface soil profile of frost boils. Profile spectra were analyzed for SOC using a calibration model developed in Unscrambler® X v.10.2 that was based on partial least squares regression and a calibration dataset for polar deserts. We found that SOC varied with depth in frost boils and that diapirs may be identified by detecting enhanced SOC at depth. These results provide a promising sign that diapirs can be detected using NIR/VIS spectrometry. We are currently investigating the plant community composition and indicator species that may be linked to diapir presence.