First-year postfire and postharvest soil temperatures in Aspen and Coniferstands

Aspen (Populus tremuloides Michx.) stands are in decline throughout the Int erior Western United States because of fire suppression, overbrowsing by do mestic livestock and native ungulates, and forestsuccession. We measured su mmertime soil temperatures in stable aspen, decadent aspen, and mixed aspen /conifer stands; a mixed aspen/conifer clearcut; a mixed aspen/conifer fore st that was burned in a lightning-caused fire; and a decadent aspen stand a nd mixed aspen/conifer stand that received prescribed burns. Soil temperatu re fluctuations and mean soil temperatures were greater in cut and burned a reas than in untreated stands. In untreated stands, mean soil temperature i ncreased in the order: mixed aspen/conifer < stable aspen < decadent aspen. Soils under the closed canopy of mixed aspen/conifer stands tended to rema in cool in the summer favoring organic matter accumulation. The relatively open canopy of decadent aspen stands allowed for increased light penetratio n and soil heating favoring organic matter breakdown. Cutting and burning g reatly increased summertime shallow soil temperature, also favoring increas ed organic matter turnover and aspen suckering. Postdisturbance regrowth of grasses and forbs and aspen suckering shaded soils. Eventually, soil tempe rature in treated or disturbed areas should approach that of stable aspen s tands.