Biodegradable
Wood is biodegradable.
When wood is no longer usable, it can be readily absorbed back into the earth with no environmental harm. Wood fibers turn into non-toxic dirt and enrich the soil as they decompose. On a building site, wood scrap can be chipped and composted immediately with no hauling and no land filling required.
Wood substitutes are not biodegradable.
Materials such as concrete rubble are very difficult to recycle or dispose of. Steel and aluminum require massive amounts of energy to recycle. Plastics are burdened with toxic substances that make recycling hazardous and costly. As well, plastic is not biodegradable and will remain in a landfill for half a millennium (500 years).
Wood waste is not a serious problem in the U.S. and accounts for only 7% of landfill space by volume. Old wood roofing and siding can be easily disposed of without worrying about toxic chemicals leaching into our drinking water and poisoning the earth.