We have initiated a long-term experiment to examine the consequences of decreases in snowpack accumulation at the Hubbard Brook Experimental Forest (HBEF), a northern hardwood dominated forest located in the White Mountains of New Hampshire. We are quantifying the eects of decreases in snowpack accumulation on root dynamics of two key tree species in this forest (sugar maple, yellow birch), microbial biomass and activity, NO À 3 and cation loss, the acid-base chemistry of drainage water, and soil±atmosphere trace gas ¯uxes. We are calibrating an existing model (SNTHERM) to depict snow depth and soil frost dynamics given past or future climate scenarios for our site. In this paper, we describe the methods we are using for the manipulation studies that began in the winter of 1997/1998 and present preliminary results from our ®rst full year of treatment. Results from our methods development eorts show that it is possible to keep plots snow free by shovelling without disturbing the forest ¯oor. Preliminary test plot work showed that the SNTHERM model is capable of depicting snow depth and soil temperatures in both control and manipulated plots at our site. Results from our ®rst full year of treatment showed that a relatively mild freezing event induced signi®cant increases in nitrogen (N) mineralization and nitri®cation rates, solute leaching and soil nitrous oxide production and caused signi®cant decreases in soil methane uptake. These results suggest that soil freezing events may be major regulators of soil biogeochemical processes and solute delivery to streams in forested watersheds. Copyright