Technical Matters: The Sustainability of American Hardwoods

Regular forest inventories demonstrate that there is net growth in the volume of nearly all commercial hardwood species in the U.S. forests and that this growth is well-distributed. So, in order to make the most sustainable use of the forest resource, we have to try to use all of the species. By using all of the available species that are in the forest and not just relying on a few select species, we can help avoid possible supply stresses that can be placed on the more popular species.

American hardwoods are sustainable and legal and also have a low environmental impact. This can be proved with wide range of information that has been gathered over the years by various forest sources. The U.S. Forest Service Inventory and Analysis (FIA) Program shows that between 1953 and 2017 the volume of U.S. hardwood growing stock increased from 5.2 billion m3 to 12 billion m3, a gain of over 130%. Independent studies such as the Seneca Creek study first commissioned by AHEC in 2008 and comprehensively reviewed and updated in 2017 demonstrates that there is less than a 1% risk of any illegal wood entering the U.S. hardwood supply chain.

Continuing scientific Life Cycle Assessment work shows that the carbon stored in American hardwoods at the point of delivery to any country in the world almost always exceeds the carbon emissions associated with extraction, processing and transport.

It is important to note that the vast majority of American hardwoods come from small privately owned forests each with an average of 15 hectares. In 2016, 89% of hardwood products were extracted from private forests and only 11% from publicly-owned forests. These small forest owners will typically harvest once or perhaps twice in a generation and because of the diverse age range of the trees that are in the forest they will only harvest the mature trees of each species. This allows light through the forest canopy so that the smaller trees can flourish and new trees can regenerate naturally from seed.

There is very little if any clear felling of American hardwoods, as is normally associated with softwood plantation where all of the trees would be planted and felled at the same time. Nearly all of the hardwood forests in North America are of naturally-regenerated mixed species with very little plantation grown trees and this improves the diversity of the forest. This wasn’t always the case, as the early settlers in the nineteenth century clear-cut a vast amount of forest, reducing some states such as Pennsylvania to around 7% forest cover. But as farmers abandoned the land and headed further west, the trees grew back, showing the forest to be remarkably resilient. The regeneration of the American hardwood forest is a global success story, showing how a forest can recover if just left to regenerate naturally.

Using the Life Cycle and Forest inventory data, AHEC has developed a range of tools which can be viewed online at americanhardwood.org. There is an interactive Forest Map, which provides detailed information on forest volume, growth and removal for individual hardwood species at state and county level throughout the U.S. The LCA tool shows the eight environmental impact categories for each timber species including carbon footprint, forest replenishment time, acidification, eutrophication for individual hardwood species, lumber thicknesses and a wide range of transport scenarios. These tools help form a document called the American Hardwood Environmental Profile (AHEP) which describes product description, quantity of timber, place of harvest and other environmental impact data that demonstrates that there is negligible risk of illegal harvest. AHEP’s can be created with every consignment of American hardwood lumber or veneer delivered to any market in the world.

By using American hardwoods in a range of different building applications, we can help the sustainability of the building industry itself. Timber is the most unique of all our materials used in design and construction, in that it is a truly renewable resource and as a living material it absorbs carbon during its growth, and it will continue to store that carbon for as long as it remains as a piece of furniture or in a building. Although there is energy used during the conversion of the timber, the amount of energy stored in the timber is greater than the energy that is used in processing and transporting. Also the amount of energy used to convert a tree into a usable piece of timber is far less than that used in the production of other non-renewable building materials, such as concrete or steel and, in particular, aluminium.

For more information on American hardwoods, please visit: www.americanhardwood.org