Weeding Trees

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Published on: Jan. 2, 2007

Last revision: Nov. 30, 2010

Farmers know that growing a crop involves much more than scattering seed on the ground and walking away. The forests on your property also are a kind of crop. Although they aren’t harvested annually, forests still require hard work to reap rewards. Managing your forest as a crop will increase the health of the forest, improve wildlife habitat and maximize your profits.

One method landowners can use to improve their forest is called crop tree management. It involves removing poor quality trees in order to provide more water, nutrients and sunlight to promote the growth of the remaining trees. Crop tree management focuses on the trees that are left to grow rather than the ones being harvested.

Cape Girardeau County landowner, Mark Nussbaum has been practicing intensive crop tree management for 10 years. He said he first looked at the species, quality and wildlife values of the trees present. His next step was “weeding the forest” by thinning the undesirable trees. This released the remaining “crop trees” from competition that would keep them from attaining their optimum growth and value.

This concept flies in the face of the practice of harvesting only large trees with the idea of “releasing” the smaller, presumably younger trees for growth.

Most forests in Missouri are even-aged due to previous heavy harvesting, and the small-diameter trees in a forest are often as old as larger trees. The trees are different sizes because some receive more sunlight, allowing them to grow at a faster rate.

Small-crowned trees that are overtopped by other trees are called suppressed trees. Many of our forests are dominated by suppressed oaks, which do not grow well in the shade of other tree species. What’s more, these trees have lost the ability for the crown to expand and, even if conditions improve, will only slowly grow in diameter. It is important not to select these suppressed trees as crop trees.

Selling Small Trees

Before your crop trees mature to their full value, you’ll be harvesting a crop of small-diameter wood. A good forest manager would take maximum advantage of this byproduct of crop tree management.

A lot of small-diameter wood becomes firewood. Although firewood sales in most areas are seasonal, there are ways to generate sales year-round. For

example, landowner Doug Kulik, who lives north of Sam A. Baker State Park in Wayne County, sells most of his firewood to campers during the summer tourist months.

Two chip mills in Missouri buy tree-length wood down to about three inches in diameter on the small end. These mills produce hardwood chips that are used to make paper.

Solid-wood products made from small-diameter wood include lumber for items such as cabinets, flooring, pallets and industrial blocking. A recent study conducted by University of Missouri Extension Forester Hank Stelzer and the Missouri Forest Products Association concluded that current sawmill technology yielded 2 percent grade lumber, 17 percent flooring, and 81 percent pallet and blocking lumber from small-diameter wood.

Sawmills have been reconfiguring so they can create wood products out of smaller diameter wood.

“Five years ago the average diameter of the logs that we processed was 14 inches,” said Jerry Lough, who owns Canoak USA, located near Salem. “Today our average log measures approximately 10.5 inches in diameter. If we didn’t adapt to these changes, there is no way we could stay competitive in today’s markets.”

Madison County Wood Products, located near Fredericktown, also recently reconfigured their sawmill to make use of smaller diameter wood. They can now process wood that is at least 20 feet in length and at least 5 inches in diameter on the small end.

At most mills it costs more to produce the same volume of high-value lumber and flooring from small wood than it does from larger logs. This could soon change, however. According to Stelzer, new sawmill technology is coming along that is capable of producing five times greater volume of pallets and industrial blocking from small-diameter wood with operating costs less than half.

High oil prices also may add value to small-diameter wood. Technology currently exists to produce biofuels (ethanol and diesel) from wood fiber.

Potlatch Corporation announced this year that it was participating in a feasibility study for a proposed biorefinery pilot project at its Cypress Bend, Arkansas, facility. The proposed plant would convert forest and agricultural waste into biofuels.

According to company Vice President Harry Seamans, preliminary estimates indicate that the biorefinery could annually produce fuels equivalent to 1.6 billion cubic feet of natural gas and 80,000 MWH of electricity per year. That’s enough natural gas to supply 20,000 homes and enough electricity to power as many as 8,000 homes!

Trees to Market

Often, the biggest challenge in making good use of small-diameter wood is finding economical ways to extract it from the forest and get it to the market or mill.

The Eastern Ozarks Forestry Council (EOFC) and the Conservation Department conducted a mechanized thinning trial of three different types of harvesting equipment.

Peter Becker, research coordinator for the EOFC, said the most efficient equipment combination for harvesting small-diameter wood is a “cut-to-length” harvester and forwarder. Although this equipment looks large and ungainly, it’s extremely efficient and has a small footprint.

“It actually exerts less ground pressure than a person walking in the woods,” Becker said.

The council and the Department are planning a wider trial of large-scale mechanized harvesting operations. The study would take place over a much longer period of time, on a variety of different sites, and in forested stands of various sizes and densities.

Landowners may be able to use cost-share funds to get the trees cut through a timber stand improvement operation. Cost-share funds are very limited, however, and competition is great.

The Missouri Forest Products Association is working on a study of Missouri’s forest resources. MFPA Executive Director Brian Brookshire said, “The MFPA is very interested in developing programs that will result in the removal and utilization of small-diameter, low-quality stems from otherwise overstocked forest stands. Removal of such material can benefit both the forest landowner and the forest industry and result in healthy, sustainable forests that are growing at optimal rates.”

The study also will help to ensure that our forest resources can support a refining facility designed to make use of forest biomass.

“We are not trying to replace any current markets by producing biomass,” Brookshire said, “but, rather, add biomass to the existing suite of wood products already being produced in Missouri. We envision this material being used to generate power and produce cellulosic ethanol in the near future.”

Forest Help

For help in managing your forest, contact a Missouri Conservation Department forester or a consulting forester in your area. Find your local Department forester by calling your nearest Conservation Department office or going online.

Find a local consulting forester by going to the Missouri Foresters web site.

Contact the Missouri Forest Products Association at 611 East Capitol Ave., Jefferson City, MO 65101, (573) 634-3252 or online.

Go to online to learn more about the Eastern Ozark Forestry Council or to view a full report on the Mechanized Thinning Trial.

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