Mechanized Thinning Trial of Upland Hardwood Forests

COOPERATIVE CONSERVATION CASE STUDY

Forestry Council Raises Awareness Of Improved Harvesting Techniques

Location: Northeastern/Mid-Atlantic

Project Summary: A thinning trial was conducted on a site typical of overstocked, saw log-sized, upland hardwood stands on steep (30%), stony terrain in the Ozarks.

Jeff Lamb

Resource Challenge

Casual management of Ozark forests on private land is largely based on the wrong notion that a tree’s size reflects its age. Thus, diameter-limit cuts are supposed to rejuvenate the forest by making room for the supposedly younger (smaller) trees as the largest (best) trees are selected for harvest. In fact, most of the trees in a typical Ozark forest are of the same age, and tree size likely reflects crown position. A tree is smaller because its crown has been shaded, and such trees usually cannot grow much larger, even if their crowns are released.

The unavoidable consequence of a conventional high-grading harvest is to degrade the stand left behind. This has been going on for a century in Missouri Ozark forests, and it isn’t good for the forest, the landowner, or the forest industry. An alternative approach, crop tree management, leaves the best trees and opens their crowns so they can grow better. Instead of growing a lot of small trees, the idea is to grow fewer, but higher value trees. Such trees are also more resistant to drought, disease, and insect attack, and they produce more seed for wildlife.

Examples of Key Partners

Eastern Ozarks Forestry Council and Mo. Department of Conservation

Results and Accomplishments

Plots were harvested by conventional (chainsaw + skidder) and mechanized (small tracked skidsteer + feller-buncher and harvester + forwarder) logging equipment. The heavy thinning removed an average of 40 t/ac of pole wood and saw logs, leaving an average saw log volume of 3,600 bf/ac. All three logging technologies proved mechanically competent in these conditions. The crawler/hotsaw was not cost effective, while the harvester/forwarder was at least as cost effective as the conventional chainsaw/skidder technology. The high productivity and utilization of the harvester/forwarder compensated for its high capital cost. Biologically and economically significant damage to the boles of residual trees was low and comparable among technologies, as were soil disturbance and compaction. Crown damage was significantly greater for the harvester/forwarder, but still acceptable. Thus, crop tree management with simultaneous removal of saw logs and pole wood is feasible at acceptable levels of environmental impact for all three technologies.

Innovation/Highlight

Demonstration of different harvesting techniques that will provide more income to private landowners and better products for the forest industry in the future.

Project Contact

Peter Becker
Research Coordinator
Eastern Ozarks Forestry Council
P.O. Box 128
Bunker, MO 63629
573-689-2121
wongbeck@yahoo.com

Gerald Bryan
Chairman
Eastern Ozarks Foresty Council
University of Missouri Extension P.O. Box 408
Cape GirardeauMO 63755
573-243-3581
Bryang@missouri.edu

Website: http://www.eofc.org

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