​​For Starters, You Degrade the Quality of Your Forest

Logs being hauled from UT's Forest Resources AgResearch and Education Center


Logs being hauled from UT's Forest Resources AgResearch and Education Center near Oak Ridge, Tenn. Photo courtesy UTIA.

 


Submitted by Wayne K. Clatterbuck, Professor, UT Department of Forestry, Wildlife & Fisheries
Dr. Clatterbuck will present this topic at the UT Institute of Agriculture’s Milan No-Till Field Day scheduled for July 28 at UT’s AgResearch and Education Center in Milan, Tenn. For more information, see the website milan.tennessee.edu

Concern exists among forest practitioners, owners, industry and the public that high-grading – the practice of harvesting those trees that will give the highest intermediate economic return – may lead to a widespread decline in the forest resource. Recent statewide forest inventory statistics (from USDA Forest Service, Forest Inventory Analysis) for Tennessee indicate that the grade of hardwood trees is diminishing. About 3 out of every 10 hardwood sawtimber trees are considered culls with minimal value or usable volume.

High-grading harvests the most saleable, and the largest, most valuable trees and leaves the poor quality, defective and low-value trees, the unacceptable growing stock to populate the next forest. The practice does not give consideration to regeneration, growth, regeneration or species composition of the future forest.

For most forests in Tennessee, smaller-diameter trees are not necessarily younger trees. Most of these smaller trees are:

• Slower growing trees of the same age, but different species, that are not capable of growing into the overstory when larger trees are removed. (These include many midstory species such as dogwood, blackgum and sourwood.);

• Trees capable of release but of an inferior species (for example, red maple);

• Trees of the same species and age as the larger trees, but that did not grow as quickly as their larger-diameter counterparts due to greater competition between trees. These trees have low vigor and sparse crowns at an advanced age with low probability of responding to overstory release.

High-grading promotes survival and growth by less well-adapted trees especially at the expense of well-adapted trees that are harvested. Because slower-growing and poor-quality trees are retained, high-grading diminishes the diversity, tree grade, and economic value of the future stand. The practice can be driven by short-term economic considerations without regard to the future forest. Immediate cash flow may be greater with high-grading, but potential environmental degradation and decreased future timber values will more than cancel the immediate cash advantage.

Avoid high-grading by leaving some desirable trees with the potential to increase in growth and value. Generally foresters recommend leaving a minimum of 50 ft2 of basal area/acre in desirable trees (acceptable growing stock) with the capability of future growth and development. If stocking of desirable trees is less than 50 ft2 of basal area/acre or if inferior, less desirable trees predominate, then the stand should be regenerated with a complete cut (silvicultural clearcut). Recent hardwood market reports indicate that prices for grade 1 sawlogs (depending on species) are 3 to 6 times greater than the poorer grade 3 logs. Higher quality (better grade) timber is more in demand, less in supply, and yields greater prices. Growing higher quality trees gives a much greater financial return during a rotation than short-term high-grading.

Through its mission of research, teaching and extension, the University of Tennessee Institute of Agriculture touches lives and provides Real. Life. Solutions. ag.tennessee.edu

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Contact:

Dr. Wayne K. Clatterbuck, Professor, UT Department of Forestry, Wildlife & Fisheries, 865 974 7346, wclatter@utk.edu