Permafrost table depth is one of critical factors for forest stand structure in Interior Alaska. We examined the relationship between permafrost depth in the growing season and forest biomass accumulation along the northeast-facing slope in Caribou-Poker Creek Research Watershed. Three black spruce stands were selected for meassurements of permafrost depth using penetration test meter. Nine points were tested in 5 meter-latice design on the forest floor. Upper slope position showed deeper permafrost table, and shallower permafrost existed in the lower position of the slope. The most less biomass accumulation stands was on the true north-facing slope.