Building materials - status of wood supply
I encountered the sentence fragment "We know that forest resources have not been managed in a manner that creates a sustainable supply of wood for home construction".
Is there substantiation for this? - Bobby
Yes, I do have some data and if others also have links to the situation with the "so callled" renewable forestry industry (less than 4% of old growth now remaining in the USA is a figure that I seem to remember) and I also found some great data on the relative embodied energy of various products. I need to get together slideshow and post it at the Yahoo Files section. The type of false PR used by the forestry industry is for example the advertising that says that they replant but they do not say that the result is not equal to the harvest for the next 40 years. Plus mon culture tree plantations are a real problem for the ecology. Metals, especially aluminum (12% of the earth's crust and in surplus supply) are the way to go, as well as glass (80% of the earth's crust, ditto) and hydrocarbon polymers (more than sufficient renewable source from Oil From Algae).
In addition to the algae biomass (which flows over the roof canopy and then blooms in a reservoir) we would also grow an aquatic plant biomass. Duckweed is a possibility and I have found a good resource here: http://www.geocities.com/RainForest/Canopy/3631/
My impressions (which may be influenced by my southeastern location - other areas may have other usage patterns):
Most house construction is of southern yellow pine - some as milled limber and much as artificial products like OSB and micro-laminated beams. There is much more grown each year than is harvested. A plantation tree will mature in 20 years.
Some oak is used for trim in up-scale houses. It is more of a break-even. And a long time to maturity - like 40 years.
Walnut and other exoctics are where the disaster is. But how many people have houses built of walnut?
Is is true the old growth left is low, but that does not affect sustainability. Nursery grown seedlings and human planting of the seedlings results in more uniform timber stocks.
(One difficulty in judging sustainability is the current housing bubble. I keep thinking it has to slow down someday and we will not need as many Macmansions with as many sq. feet as are being constructed today.)
(My point in raising this issue was not that we do not need to move to better materials, but the narrow technical question of, "Are we are growing enough pine to build enough modest homes to meet our needs." I agree we should try other materials, styles, and technologies.)
Dr. Landseman is the expert I was saying liked duckweed - small world - Bobby