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TreeGirdlingTools

Bill KilroyMechanical Engineering Technician

Keith WindellProject Leader

USDA Forest ServiceTechnology and Development ProgramMissoula, Montana

5E52E60—Small Area Forestry Equipment

May 1999

The Forest Service, United States Department of Agriculture, has developed this information for the guidance of itsemployees, its contractors, and its cooperating Federal and State agencies, and is not responsible for the interpretationor use of this information by anyone except its own employees. The use of trade, firm, or corporation names in thispublication is for the information and convenience of the reader, and does not constitute an endorsement by theDepartment of any product or service to the exclusion of others that may be suitable. The United States Department ofAgriculture (USDA), prohibits discrimination in all its programs and activities on the basis of race, color, national origin,gender, religion, age, disability, political beliefs, sexual orientation, and marital or family status. (Not all prohibited basesapply to all programs.) Persons with disabilities who require alternative means for communication of program information(Braille, large print, audiotape, and so forth) should phone USDA’s TARGET Center at (202) 720-2600 (voice and TDD).To file a complaint of discrimination, write: USDA, Director, Office of Civil Rights, Room 326-W, Whitten Building, 14th andIndependence Avenue SW, Washington, DC 20250-9410, or call (202) 720-5964 (voice or TDD). USDA is an equalopportunity provider and employer.

TreeGirdlingTools

United StatesDepartment ofAgriculture

Forest Service

Technology &DevelopmentProgram

2400 TimberMay 19999924-2809-MTDC

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TABLE OF CONTENTS

INTRODUCTION _______________________________________________________ 3

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GIRDLING TOOL EVALUATION ___________________________________ 5

TOOLS EVALUATED __________________________________________ 6

MISCELLANEOUS OPERATING NOTES _____________________________ 7

EVALUATION DATA __________________________________________ 7

OPERATOR COMMENTS _______________________________________ 9

DISCUSSION POINTS ________________________________________ 10

CONCLUSIONS ____________________________________________ 10

COMMERCIALLY AVAILABLE GIRDLING TOOLS ______________________ 11

GIRDLING TOOLS THAT ARE NOT COMMERCIALLY AVAILABLE ___________ 13

HAND TOOLS USED FOR GIRDLING ______________________________ 14

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Figure 1—Girdling severs a ring of the barkand cambium layer encircling the tree.

INTRODUCTION

Figure 2—When a chain saw is used forgirdling, parallel groves are cut through thebark several inches apart.

Figure 3—A sharp chisel-type tool is needed toremove the bark between the chain saw cuts.

Figure 4—Double hacking is the most effec-tive method of girdling a tree with an ax.

Silvicultural operations, especially those involved in molding young stands, sometimes require killing

unwanted trees. Also at times, trees arekilled and left standing to enhancewildlife habitat. Girdling is the traditionalmethod of killing trees without fellingthem. Girdling severs the bark, cam-bium, and sometimes the sapwood in aring extending entirely around the trunkof the tree (Figure 1). If this ring is wideenough and deep enough, it will keepthe cambium layer from growing backtogether.

Cutting deep into the heartwood canalso create a hazard tree.

Any leafing branches on the trunk belowthe girdling ring must be cut off tocompletely kill the tree. An efficientgirdling tool must be capable of cuttingthe girdling ring and removing limbs.

Few tools on the market are designedspecifically for girdling operations, butmany can be used as girdling tools. Thisevaluation compared four girdlers. Twotools were specifically designed forgirdling, while two were commonly usedfor other forestry operations. A marketsearch was conducted to determinesuitable tools that were commerciallyavailable.

Chain saws, axes, or many othercutting devices are used to girdle a tree.With either a chain saw or hand saw,the proper girdling technique is to cutparallel, horizontal grooves through thebark several inches apart (Figure 2).Afterward, the bark and cambium layersbetween the cuts can be peeled away. Asharp, chisel-type tool is needed tocompletely remove the bark andcambium (Figure 3).

When the phloem layer is completelycut, the tree can no longer transportcarbohydrates produced in the needlesor leaves to the roots. The roots diewhen the carbohydrates in them havebeen exhausted, a process that maytake several years. Severing thesapwood hastens the death of thecrown (by reducing the flow of water,stored substances, and inorganicnutrients to it), but may also encouragesprouting because water and nutrientsthat can no longer be used by thefoliage are available for sprouting.

The most effective method of girdlingwith an ax involves hacking a linearound the tree with a series of down-ward blows, then hacking a second line3 inches above the first. This procedureis called double hacking (Figure 4). Thematerial between the two lines must bepried out with the ax blade.

Applying herbicide after a single line ofax cuts has been made around a tree isalso effective. This technique is calledfrilling. A single line of narrow cutsseldom works without herbicide.

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Figure 5—The number and size of limbs,terrain, and other factors affect the time that’sneeded for girdling and the cost of girdling.

Notching involves cutting a deep ringthrough the bark and a half-inch or moreinto the sapwood, completely encirclinga tree. This method will halt the flow ofnutrients and water from the roots to thecrown of the tree and will kill the treequickly. However, notching encouragessprouting.

The time of year is a factor indetermining the effectiveness of girdling.The plant is most vulnerable early in thegrowing season just after rapid tissuegrowth has depleted carbohydratereserves. Also, the bark is “loose” inspring and early summer when thecambium is active, making the barkeasier to peel. Later in the year, the

cambium is more difficult to remove,especially in larger trees.

The time and cost of girdling depend onthe tree species and the average stemdiameter. Additional considerationsinclude tree density, bark thickness, theamount of limbing necessary (Figure 5),and terrain factors that affect a crew’sability to get around. These may includesuch things as the slope of the terrain,the amount of down timber in the area,and the density of the underbrush.

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