Comparison of the Microclimates of a Small Aspen Grove and Adjacent Prairie in Saskatchewan

Abstract

The microclimate of a small aspen grove in central Saskatchewan was moni- tored between December 1993 and April 1995 and compared with that of the adjacent prai- rie. Inside the grove solar radiation was reduced to 55% in winter and 23% in summer compared with the open prairie. Daily maximum air temperatures averaged 2.5 C higher in the grove just before leaf-out and 1.5 C lower just before leaf fall; daily minimum tempera- tures averaged ca. 0.4 C lower inside the grove throughout the year. Relative humidity was usually 3-4% higher inside the grove, with daily minima as much as 14% higher during the summer. The aspen grove trapped up to 45 cm of additional snow during the 1st winter, but only 5 cm more during the 2nd winter, when regional snowfall was well below normal. In midsummer the near-surface soil was 6-8 C warmer on the prairie, but by midwinter had become ca. 6 C cooler than in the grove; these differences diminished with depth. The annual range of soil temperature at a depth of 10 cm was 24 C inside the grove compared to 38 C outside. Windspeed inside the grove was reduced to 7% of the external value in summer and to 28% during the winter. Calculated windchill values were 15% lower inside the grove as a result of the reduction in windspeed. The potential importance of aspen groves as wildlife habitat is discussed.