The new environmentalism, besides lobbying to persuade political interests and educating consumers on how to protect natural resources and ecosystems, has gained ground in many industries from wood manufacturing to landscaping to architecture. Sustainability of our natural resources has seen a rebirth. This drive to conserve our natural resources has seen a re-emergence among many individuals, groups and companies to seek alternative sources rather than deplete that resources that are nearly gone.
Why Black Locust?
At the American Society of Landscape Architects (ASLA) 2011 annual meeting, more than 6,000 landscape architect professionals gathered for forums, lectures and discussions about sustainable methods in design, and among the hot topic was black locust wood. What does a seemingly non-invasive native tree found in southern Pennsylvania to northern Georgia and Alabama and as far west as Oklahoma, have to do with the possibility of domestically-grown sustainable forestry and wood harvesting? Perhaps, more than we know.
A research project presented at the 2011 ASLA meeting by the Michael Van Valkenburgh Associates show a plantation in Hungary producing a wide range of black locust trees, including some trees with the potential to produce top quality wood. The plantation in Hungary found that black locust trees can be grown only in areas where oak cannot be established. With the assistance of a local forestry research organization and local wood producers, 8500 hectares, or 21,000 acres of dense black locust forests are being harvested yearly for production. Another 700,000 ha (1.7 million acres) of abandoned agricultural fields are to be forested within the next 50 years creating an additional 35 to 40 percent more black locust plantations in Hungary. Why the overabundance of black locust trees. Black locust wood, amongst it many properties, is heavy and hard which translates into remarkable durability. It’s fast growing, and a black locust tree can gain more than 4 feet in height per year in good conditions. Best of all its naturally resistant to rot and insect infestation. While its native to the United States, it tends to take root in areas that other trees can’t, making it extremely adaptable to surrounding conditions and fertile in densely planted areas. In Europe and Asia the black locust tree is an acceptable crop, and a number of countries are moving forward with planting huge forests for wood production, something hasn’t happened in the United States.
Because of its fast-growing properties, the government gave black locust trees to the early U.S. settlers. Within 15 to 20 years, the tree could be cut down and used as firewood. At 30 years of age it can be used in production for building materials. Today, even lesser-grade black locust wood can be used for many other products including mulch, biomass fuel, parquet and greenhouse poles making the tree entirely useful with none of its parts wasted.
Upgrading the Domestic Black Locust Industry
While the black locust market remains in its infancy in the U.S., worldwide there are 5 million acres of black locust in cultivation, and virtually zero here in the United States. In other parts of the world, the black locust tree isn’t seen as an invasive pest as it is in the United States. Korea has 1.2 million acres, China has 1 million acres and Hungary has 270,000 acres of black locust forests.
In fact, tracing the origins of the black locust tree in America finds it being extensively used by the Amish. The Amish, notoriously known for not wasting any part of their timber or lumber, use black locust wood, having perfected unique techniques over generations that reveals a template for possible future black locust production. The secret to their black locust production techniques is using a proper kiln drying method.
Black Locust Kiln-Drying Method
Because of the wood’s natural ability to resist rot and insect infestations, black locust wood is a bit tricky to dry. The most difficult portion is achieving the 12 percent moisture content. According to the Purdue University’s Department of Forestry and Natural Resources, black locust wood can weight 48.2 pounds per cubic feet with a 12 percent moisture content, making it as heavy and dense as most oaks. During the drying process, the wood’s total volumetric shrinkage is 10.2 percent, a very low shrink rate, which makes it very stable when working with it.
The complex multi-level kiln drying process involves letting freshly cut wood air dry first, followed by a kiln-drying using a dehumidifier kiln. According to woodcrafters, kiln drying black locust wood is not for the lazy, it requires extreme diligence and patience to follow its very strict process and its 40 to 50 days of air drying before it can be used in production. While drying it takes time, many landscape architects and woodcrafters consider it worth it. Beyond its environmental sustainability, it’s extremely cost effective at $5.44 per square foot as compared to other woods with the same properties.