USING THE RATE OF ACCUMULATED FREEZING AND THAWING DEGREE DAYS AS A SURROGATE FOR DETERMINING FREEZING DEPTH IN A TEMPERATE FOREST SOIL

ABSTRACT: A changing climate may bring about more precipitation but less snowfall to Northeastern North America. A decreased snowpack may impact soil freeze-thaw cycles. The objective of this study is to evaluate the usefulness of Freezing Degree Days (FDDs) and Thawing Degree Days (TDDs) as a surrogate for a direct measure of frost depth in soils in a temperate forest. Frost tubes were used as a direct measure of soil freezing depth. While a strong correlation is found linking total accumulated FDDs with soil freezing depths in areas free of snowpack, a better predictive tool is to relate soil freezing depth with the rate at which FDDs are accumulated (expressed as FDD/day). Accumulating FDDs at a rate of more than 4.0 FDD/day resulted in a growing freezing depth, while accumulations of less than 4.0 resulted in the thawing of the frozen soil. The degree-day approach was not successful in determining frost depths in the presence of a snowpack