There are a number of excellent websites which will explain the terms sustainable and renewable and what they mean within the forestry and timber industry in Australia. These include:
www.forests.nsw.gov.au/management www.naturallybetter.com.au http://adl.brs.gov.au/forestsaustralia/index.html
At the end of its useful first life timber is also reusable, recyclable and can also be used to generate renewable energy (either domestic or industrial). www.timberstewardship.org.au is an excellent source of information about these aspects of timber industry in Australia.