Jim and et al.,
this simple calculation demonstrates that there is not enough forest in
North America to supply current per capita consumption of wood. I took the
data from materials web. The Pulp and Paper Institute of Canada provides per
capita consumption rates on wood consumption.
We are living off 'natural capital' that has to be replaced, but the average
growth rates are not sufficient to meet the demand for wood. We would need
about 3 billion hectares of commercial forest in north america.
The CSA and various sites provide that the average life expectancy of a wood
stick frame house is 60 years; insurance companies often use 40 years.
http://www.matweb.com/GetUnits.asp?convertfrom=g/cc&value=0.48
Douglas-fir density
kg/m³ = 480
Per capita North American consumption of wood = 300 kilograms per year.
300 million persons = 9 X 10^10 kilograms/480 kilograms/m^3 = 188 million
meters^3 per year
Average growth rate = 4.5 meters^3/hectare = 42 million hectares per year
required to be harvested
Average rotation age = 72 years (culmination age of Douglas-fir on good
site)
72 X 42 million hectares required to supply 300 million persons in North
America
= 30 million square kilometers of Douglas-fir is required.
OR 3 billion hectares.
(eg. BC has 24 million hectares in total that forests are grown on for
commercial purposes)
(400 million acres of commercial forest in the US)
Conclusion: there is not enough forest in North America to supply this
amount of wood
http://www.matweb.com/GetUnits.asp?convertfrom=g/cc&value=0.48
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