Crop Tree Release is a Management Method to Consider

Alabama timber managers have different reasons for owning and managing their woodlands. Some desire woodlands that provide habitat for a variety of wildlife. Others want woodland that supports particular types of trees for recreation such as hiking, hunting, and bird watching. Still others want to harvest timber from their forest for home and farm use or to provide periodic income. No matter what the goal, most timber managers aspire to maintain or improve the health, vigor, and attractiveness of their forest. For forest owners who want to grow trees for financial return, crop tree management is a concept that they should consider.

Forest Stand Improvement (FSI) is a forest management tool used to enhance growth rates of timber and shorten the time required for hardwood crops to mature. FSI provides an opportunity for the landowner to control, manipulate, and improve the growth, quality, and species composition of a timber stand. One method of FSI is Crop Tree Release (CTR), the practice of deadening selected trees in younger, overstocked forests for the benefit of releasing desirable crop trees.

Dr. Robert Parker manages timber in Elmore County. His goal was to protect and enhance optimum wildlife habitat, promote high quality hardwoods (mainly red oak and white oak), and increase understory cover by increasing the amount of light reaching the forest floor. He contacted USDA-Natural Resources Conservation Service (NRCS) and asked for assistance in learning more about CTR. Tim Albritton, NRCS State Staff Forester, helped Dr. Parker identify a 1/5 acre Crop Tree Inventory plot, which they used to establish a sampling of his forest. Blue flags were used to mark plot center and delineate the plot boundaries. Crop trees would be marked with pink flags and red flags would be used to mark trees to be cut or killed to release the crop trees from competition. To begin selecting crop trees, they looked for the single tree on the plot that best fit Dr. Parker’s goals and objectives. They identified and flagged a high quality white oak, 12 inches in diameter. Looking up, they then identified the trees surrounding the oak whose crowns touched the oak crown. One sweetgum and an ash were identified and flagged as “cut trees”. They continued walking the 1/5 acre plot identifying and flagging crop trees and cut trees.

A total of nine crop trees (one post oak, two water oaks, and six white oaks) were identified, which equals 40 crop trees per acre. The average diameter at breast height (DBH) of the crop trees was 11.2 inches. In as little as 10-15 years, some of these crop trees may have significant timber value. An 18 year-old hardwood stand that naturally regenerated from stump sprouts and seed after a clearcut.

Twelve cut trees were identified (three yellow poplar, three ash, one sweetgum, and five water oaks), which equals 60 cut trees per acre. The average DBH of the cut trees was 9.4 inches. Although most of the cut trees had some poor form characteristics (sweep, crook, low fork, etc.), some were of merchantable size and could be sawn into lumber for special projects or used as firewood.

The procedure for deadening the trees with a chainsaw:

• Turn the saw sideways and cut a complete girdle (ring) around the tree at a comfortable height (usually around 3’)
• Then cut a second girdle 4 to 6” from the first.
• Each girdle should be cut completely through the bark and into the live wood at least ¾ inch.
• Make sure that the girdle meets at both ends so the phloem, cambium, and xylem is completely severed.

Through this field visit, NRCS technical assistance provided data which will help Dr. Parker make good land-use decisions based on his forest management goals. Key points of the crop tree management techniques for applying FSI were identified as:

• Begin the process by identifying high-value “crop trees”
• Any tree with a crown that contacts the crop tree crown is marked as a “cut tree”
• Trees that do not contact a crop tree crown, or are growing below a crop tree crown, can be passed over since they do not compete for light with crop trees
• Sunlight is the most critical resource for forest trees; look up to determine which trees might be competing with crop trees for light

The Environmental Quality Incentives Program (EQIP) has cost-share practices for FSI. The EQIP program, which is administered by USDA-NRCS, assists private landowners, helping them to address natural resource problems which threaten environmental quality. Cost share is a proven means of overcoming landowner reluctance to make long-term investments in public goods. The cost-share assistance encourages landowners to make long-term investments in maintaining the natural resource base, particularly land management practices capable of arresting or reversing damage to environmentally sensitive areas. The minimum number of crop trees per acre needed to quality for EQIP Crop Tree Release cost-share is 30.

Private landowners are beginning to view their hardwood forests as a vital part of their farming operation. The slow growth rates of hardwood trees have long been viewed as an obstacle to forest management. When applied properly, CTR results in a faster-growing, healthier forest composed of a greater percentage of more acceptable trees.

The technical assistance available through USDA-NRCS provides data that enables forest producers to make good land-use decisions. Cost-share programs are available to help timber producers accomplish their established goals. For more information, contact your local NRCS office. For a copy of the Crop Tree Release in Precommercial Hardwood Stands publication, go to the following site:  http://www.al.nrcs.usda.gov/about/so_sect/ec_sc/forestry.html.

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