The impact of forest structure on near-ground temperatures during two years of contrasting temperature extremes

The thermal environment of clear-cut, partially cut, and uncut forest sites in northern Wisconsin are examined for a warm year and a cool year. Temperatures at 0.5 m above and 0.05 m below ground, as well as base 5°C heat sums are computed for each site between May and September and differences between cut and uncut sites compared for the 2 years. Differences in average and minimum air temperature and soil temperature are less than instrumental error, ε=0.3°C. Maximum air temperature differences between the clear-cut and uncut sites drop from 5.7°C in the cool year to 4.7°C in the warm year, while the difference for the partial cut drops from 3.2 to 2.7°C. The results suggest that studies of tree growth or forest development and climate change should consider the effects of forest structure on changes in daily extreme temperatures.