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Mixedwoods – A discussion. Smith et al 1997 Chapter 16 Comeau 1996 Man and Lieffers 1999. Why mixedwoods?. 1) Mixedwoods are a natural part of the landscape 2) Visual resource – aesthetic (they look nice) 3) Diversity 4) Forest Health and risk of loss
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Mixedwoods – A discussion Smith et al 1997 Chapter 16 Comeau 1996 Man and Lieffers 1999
Why mixedwoods? • 1) Mixedwoods are a natural part of the landscape • 2) Visual resource – aesthetic (they look nice) • 3) Diversity • 4) Forest Health and risk of loss • 5) Nurse Crop • a. Reducing vigor of grasses, herbs and shrubs • b. Carbon transfer between roots that share the same mycorrhizae • c. Frost protection • 6) Nutrient availability and cycling • 7) Yield • 8) Economics
SVF and Transmittance vs opening diameter (in tree lengths), where trans in undisturbed stand is 20%
“Successional falldown” • Reduction in conifer volume resulting from increased abundance of pioneer deciduous tree species following harvesting • Stand tending practices (site preparation, vegetation management, spacing, cleaning) can reduce this “falldown”
Light (transmittance) levels decline as birch basal area increases (Comeau 1996)ln(t)=-0.2122 x ban=110, R2=0.759, RMSE=0.804
Light (transmittance) levels decline as aspen basal area increasesln(t)=-0.06727 x ban=68 R2=0.917 RMSE=0.453(Comeau (in press))
Vertical gradient of light under aspendifn=0.4502 + 0.7481 x relht +0.5070 x (relht)2 – 0.7058 x (relht)3(n=48 R2=0.858 RMSE=0.1143)Comeau (in press)