Canadian Forest Service Publications

Effects of forestry practices on forest microclimate. 2001. Reynolds, P.E. Pages 623-634 in Ecosystems and Sustainable Development III: 10 Advances in Ecological Sciences Y. Villacampa, C.A. Brebbia and J-J. Uso, editors. WIT Press, Southhampton, Boston.

Year: 2001

Issued by: Great Lakes Forestry Centre

Catalog ID: 35452

Language: English

Availability: PDF (request by e-mail)

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The Fallingsnow Ecosystem Project was initiated in northwestern Ontario in 1993 to assess the effects of alternative conifer release practices on ecosystem processes and components. Treatments included two herbicides, glyphosate (G) and triclopyr (T), and two cutting treatments, manually with brushsaws (B), and mechanically with a Silvana (S) Selective mower. Treatments were applied to 4 clearcut blocks, each 30-60 ha, harvested between 1986 and 1988, and planted with spruce. Clearcut controls (C), 5-7 yrs old in 1993, constituted a 5th treatment, and unharvested forest (F) controls, approximately 100 yrs old and consisting of mixedwood species adjacent to each block, constituted a 6th treatment. Study objectives were to quantify treatment-related microclimatic differences and to assess the duration of these differences. Weather stations, programmed to continuously monitor light, air and soil temperatures, and relative humidities were deployed on a maximum of 3 blocks from 1994 through 1998 in the C, B, G, and F treatments. Repeated measures ANOVA's were used to assess seasonal (June through October) treatment differences in 1998 for 2 replicated blocks. Analyses revealed significant treatment differences for 20 of 22 measured parameters. Release treatments were characterized by more light, higher air and soil temperatures, and lower humidities 5 years after treatments. Less light and higher humidity were observed for the unharvested forest compared with the clearcut control 12 years after harvesting. Seasonal air temperature extremes, for daily highs and lows, were associated with the glyphosate treatment, where non-woody vegetation was dominant. Mean daily high soil temperatures remained highest for the glyphosate treatment, and higher than for all other treatments. These data suggest that the effects of routine forestry practices in altering forest microclimate are longer-lasting than anticipated. Changes in forest microclimate are likely contributing to global warming and to global environmental change. The extent and significance of these contributions are yet to be determined.