The Wolf Creek Research Basin (drainage area about 195 km2) lies in southern mountainous headwaters of the Yukon River Basin in the subarctic region of northwestern Canada. The sub-arctic continental climate is characterized by a large seasonal variation in temperature, low relative humidity and relatively low precipitation. Mean annual temperature is in the order of -3°C with summer and winter monthly ranges of 5°C-15°C, and -100°C- -20°C, respectively. Summer and winter extremes of 25°C and -40°C are not uncommon. Mean annual precipitation is 300 to 400 mm per year with approximately 40 percent falling as snow. With a general northeasterly aspect, elevations range from 800 to 2250 m with the median elevation at 1325 m. Wolf Creek is situated within the Boreal Cordillera ecozone (Environment Canada, 1995) [occupying the southern Yukon and northern half of British Columbia, bordered by the Coast Mountains to the west and extends north from the Montane Cordillera to the Mackenzie and Selwynn Mountains beyond Dawson City and Keno in the Yukon; to the east, it reaches as far as the Peace River country] and consists of three principle ecosystems, boreal forest, sub-alpine taiga (shrub-tundra) and alpine tundra with proportions of 22, 58 and 20% respectively of the total basin area. Permafrost is present in locations on north facing slopes and there is sporadic permafrost throughout the basin, with prevalence increasing with elevation. Study plots are located within each of the ecosystems at elevations of 750, 1250 and 1615 m respectively. The forest site is relatively level with gently undulating terrain consisting of an alternating hummock and hollow landscape. The canopy is dense, consisting primarily of white spruce to heights of approximately 20 m, with some poplar trees to approximately 15 m. The subalpine taiga site is located on an east facing moderate hillslope of approximately 15 degrees. The hillslope itself consists of undulating terrain with numerous hummocks and depressions. The site is vegetated with shrub alder and willow to heights of approximately 2 m. The alpine tundra site occupies a windswept ridge top plateau. Approximately 50% of the site is relatively level, with the balance sloping at approximately 15 degrees to the south. Vegetation is sparse consisting of mosses, some grasses and lichens with occasional patches of scrub willow no more than 0.2 m high. Various research projects (University of Saskatchewan, Environment Canada) provide and maintain micrometeorological and hydrological instrumentation. Stations (links to real-time data): Alpine: http://giws.usask.ca/telemetry/WolfCreek/mobile/Alpinechart_mob.html Buckbrush: http://giws.usask.ca/telemetry/WolfCreek/mobile/Buckbrushchart_mob.html Forest: http://giws.usask.ca/telemetry/WolfCreek/mobile/Forestchart_mob.html