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Effects of Clearcut Harvesting & Alternative Vegetation Management on Forest Microclimate. P.E. Reynolds Canadian Forest Service Sault Ste. Marie, Ontario, Canada. Cooperators. Ontario Forest Research Institute: R.A. Lautenschlager & F.W. Bell & University of Guelph:
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Effects of Clearcut Harvesting&Alternative Vegetation ManagementonForest Microclimate P.E. Reynolds Canadian Forest Service Sault Ste. Marie, Ontario, Canada
Cooperators Ontario Forest Research Institute: R.A. Lautenschlager & F.W. Bell & University of Guelph: A.M. Gordon, J.A. Simpson, & D.A. Gresch
Specials thanks to: D.A. Buckley Canadian Forest Service Sault Ste. Marie, Ontario, Canada Retired
Objectives: • To quantify treatment-related microclimatic differences resulting from harvesting & alternative vegetation management practices • To assess the duration of these differences
Treatments: • Unharvested forest (F) blocks -- 100 yrs; aspen, fir, white birch • Clearcut control (C) -- harvested 1986 through 1988; planted with spruce • 2 alternative herbicides, glyphosate (G) & triclopyr (T), applied August 1993 • 2 alternative cutting methods, brushsaws (B) & Silvana mower (S), September 1993
Methods: • Vegetation treatments applied to 4 clearcut blocks (30-60 ha each). • Weather stations established in F, C, B, and G treatments on 3 blocks 1994-1998 • Programmed to continuously monitor PAR, RH, & air temperatures at 0.25 & 2.0 m above forest floor & soil temps at 5 & 15 cm • Repeated measures ANOVA on 5th yr data
Results: • Are based upon daily measurements of PAR, air & soil temperatures, & RH for the period Jun 2 through October 14, 1998 • Data are means for 2 replicate blocks • 5 years after B & G treatments • 12 years after harvesting • Significant treatment differences for 20 of 22 measured parameters
Results: • Lower PAR & higher RH were observed for the unharvested forest (F) compared with the clearcut control (C)
Results: • Seasonal air temperature extremes (o C), for daily highs and lows, were associated with the glyphosate (G) treatment, where non-woody vegetation was dominant (J. Sust. For. 10, No. 3/4, 2000, pp. 267-275)
Results: • Mean seasonal soil temperatures at 15 cm depth (daily highs) remained highest for the glyphosate (G) treatment, and higher than for all other treatments
Conclusions: • 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 & to global environmental change • The extent & significance of these contributions are yet to be determined