Seasonal snowpack characteristics influence soil temperature and water content at multiple scales in interior western US mountain ecosystems

Mountain snowpacks directly and indirectly influence soil temperature (T-soil) and soil water content (theta). Vegetation, soil organisms, and associated biogeochemical processes certainly respond to snowpack-related variability in the soil biophysical environment, but there is currently a poor understanding of how snow-soil interactions vary in time and across the mountain landscape. Using data from a network of automated snowpack monitoring stations in the interior western U. S., we quantified seasonal and landscape patterns in T-soil and theta, and their dependence on snowpack characteristics over an eleven year period. Elevation gradients in T-soil were absent beneath winter snowpacks, despite large gradients in air temperature (T-air). Winter T-soil was warmer and less variable than T-air, but interannual and across-site variations in T-soil were likely large enough to impact biogeochemical processes. Winter theta varied between years and across sites, but during a given winter at a site it changed little between the start of snowpack accumulation and the initiation of spring snowmelt. Winter T-soil and theta were both higher when early winter snow accumulation was greater. Summer theta was lower when summer T-air was high. Depending on the site and the year examined, summer theta was higher when there was greater summer precipitation, a larger snowpack, later snowpack melt, or a combination of these factors. We found that snowpack-related variability in the soil environment was of sufficient magnitude to influence biogeochemical processes in snow-dominated ecosystems.