Hybrid Trees
DB: This is Earth and Sky, on fast-growing trees.
JB: Tree geneticist Don Riemenschneider has been experimenting with the growth rates of poplars, aspens, and cottonwoods – at the U.S. Forest Service Forestry Sciences Lab in Rhinelander, Wisconsin. These trees are common in the Great Lakes states, and they’re often used to make paper or building products.
DB: These species of trees are also easy to crossbreed, or “hybrid-ize.” Riemenschneider’s team has developed some hybrid poplars that grow four or more times faster than wild trees. A poplar is ready to harvest when it’s about 20 meters – or about 60 feet – tall. Usually, it takes 40 or 50 years for a poplar to grow that big – but the hybrid trees reach that size in only 10 to 12 years.
JB: Thousands of acres of the fast-growing poplars are already growing, planted by a Midwestern paper company. And the state of Minnesota has approved the construction of a super-efficient power station that will be fueled by hybrid poplars, grown instead of corn or soybeans by local farmers. The hope is that agroforestry – where the “crops” are fast-growing trees – may be a way to meet the demand for aspen trees – while reducing the pressure to cut trees in national forests.
DB: For today, that’s our show – made possible in part by the National Fish and Wildlife Foundation. We’re Block and Byrd for Earth and Sky.
Our thanks to the following individual who assisted in the preparation of this script:
Dr. Don E. Riemenschneider
Geneticist and Project Leader
Research and Development
North Central Research Station
Forestry Sciences Lab
USDA Forest Service
Rhinelander, WI
The following articles and websites were used in preparing this script:
Riemenschneider, Don E., Daniel A. Netzer, and William E. Berguson. ““Intensive culture of hybrid poplars in Minnesota.”“:http://www.woodycrops.org/paducah/riemenschneider.html Paper presented at the First Conference of the Short Rotation Woody Crops Operations Working Group, Paducah, Kentucky, September 23-25, 1996.
St. Anthony, Neal. ““Former Xcel engineer sees clean energy in the trees.”“:http://webserv3.startribune.com/stOnLine/cgi-bin/article?thisSlug=NEAL08&date=08-Dec-2000&word=neal&word=anthony&word=st Star Tribune, Minneapolis, Minnesota, Dec. 8, 2000, page 1D.
Don Riemenschneider’s web site (USDA Forest Service)
Author’s notes:
In just the last 20 years, aspen, once ignored by the timber industry, has become a significant resource, particularly for the manufacture of strandboard, which is used like plywood in home construction. These days in the states of Minnesota, Michigan and Wisconsin, about half of all the wood harvested for use by the pulp and paper industry is aspens, according to Don Riemenschneider.
Besides identifying hybrid trees that grow quickly, Dr. Riemenschneider is also working to identify hybrids that grow well with minimal amounts of fertilizer. Reducing the use of fertilizer will bring economic benefitsthe trees will be less costly to growand also environmental benefits, since run-off that contains farm fertilizers can be a significant contributor to surface water pollution.
One challenge to growing “farmed” trees is that the young seedlings can be outcompeted and overwhelmed by weeds. With other crops, the solution is often to treat the weeds with an herbicide. The tree-breeding program is working to identify hybrids that are resistant to herbicides, so that the control chemicals can work most effectively.
One unique benefit to planting aspens and related trees as a crop as that when the trees are cut, new trees sprout from the roots the next growing season.
Don Riemenschneider envisions that the fast-growing trees could be planted in soil that is of marginal value for other kinds of agriculture. Also, he says the trees can be planted in buffer strips around wetlands and along rivers, to helps to control erosion, filter farm runoff, and keep streams and rivers clean. Finally, he sees the trees as a source of renewable “bioenergy.” The 50-megawatt bio-fueled power plant that has been proposed for Minnesota will burn wood far more efficiently and completely than conventional wood stoves do, while the waste heat from the power production process will go to dry fresh-cut wood before it is burned.
Additional Teacher Resources
U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Biomass Program: “Hybrid Poplar Research”: http://www1.eere.energy.gov/biomass/pdfs/hybrid_poplar.pdf
Dedicated woody biomass such as hybrid poplars could be developed as a viable energy and fiber resource. This report explains how, and covers the benefits of woody biomass. This site also contains links to more information on biomass as a renewable energy.
USDA Forest Service and the National Agroforestry Center: “What is Agroforestry?”: http://www.unl.edu/nac/index.htm
A great site for young students to learn to understand agroforesty. The site also provides a variety of links that enable students to find more information.
