Chainsaws are synonymous with forestry. Loggers use them to fell timber on steeper terrain and process logs to length (also referred to as “bucking”). Wildland firefighters use them to drop flaming snags near fire breaks and displace burnable fuel. Landowners can also use them to facilitate active forest management. Management practices could be for wildlife: edge feathering, standing dead snag creation, or hinge-cutting; or forestry: early or mid-rotation timber stand improvement practices, pruning, creating canopy gaps or midstory/understory control to enhance regeneration efforts. For most of these activities, ring girdling of trees may be a sizeable component of the job specifications. The landowner should be well-aware of how to perform this operation safely and efficiently. After all, a little “sweat equity” from using a chainsaw tends to increase eagerness to conduct resource management endeavors and self-approval after completion!
Personal Protective Equipment
First and foremost, safe chainsaw operation is paramount to job implementation. The person who engages in chainsaw use should utilize appropriate personal protective equipment (PPE) to safeguard one’s well-being. The “DIY” sawyer should have (at a minimum) chainsaw chaps, a helmet/hardhat, eye protection, hearing protection, gloves, thick leather work boots, and water for hydration. *A general rule of thumb the author picked up during wildfire detail: 3 bottles of water to every Gatorade® (electrolytes). Chainsaw safety is a top priority! If one is not equipped or mentally/physically prepared, postpone implementation…one mistake is all it takes to create a “bad day” in the field or worse!
Additional suggested items include a wedge (for both directional felling and to assist with extracting bound saw blades), hammer/hatchet to drive a wedge, chainsaw sharpening kit (a sharp set of teeth reduces labor time), 2-way radio, and a high-visibility vest. Snake-proof boots also give “peace of mind” to the sawyer when circling the base of trees or moving between trees during girdling!
Ring girdling is probably the “safest” form of chainsaw use that can be executed in forest management. Large trees can be girdled instead of felled, and cuts (girdles) can be directed at a comfortable height (waist level). The procedure involves cutting a complete (ring around the entire stem circumference) single ring or double rings around the targeted stem. Literature suggests that a minimum of 4 up to 8 inches or greater be between double girdles.
Cutting depth should penetrate past the cambium and phloem (into the xylem) to a depth of approximately 1.5 inches to successfully “starve” the tree. Death ultimately results from upsetting the carbon/nitrogen balance and auxin production/distribution throughout the tree (Noel 1970).
Seasonal Timing
Most chainsaw enthusiasts prefer to be active in the cool season to alleviate heat, pests, and humidity. However, research has suggested that plants are most vulnerable in the early growing season from spring to early summer (Kilroy and Windell 1999). Early summer cut surface treatments have been suggested to be optimal for controlling basal sprouts (Clark and Liming 1953). Cut surface treatments (with herbicide) applied in the growing season yielded the best overall efficacy (Ballard and Nowak 2006). Treatments in the growing season will promote the depletion of carbohydrate reserves in the root system. Mid-winter through early spring may provide adequate results for some species such as sugar maple and hickory but have inferior effects on other species such as blackgum (Rathfon and Saunders 2012). Mortality of stems may occur in the first year but could take multiple years before the tree finally dies.
Number of Girdles & Herbicide Use
Time is fleeting and precious to all landowners. Thus, labor time can likely be reduced if trees only need to receive one ring girdle, but is only one girdle sufficient to both top-kill and eliminate basal sprouting? This answer varies by species and the size of the stem being targeted. According to Rathfon and Saunders (2012), single rings induce less mortality and higher sprouting than double rings in some hardwood species. Wiant and Walker (1961) considered ring-porous (oak) species to be more easily killed than diffuse-porous species (maples, cottonwood, gum, black cherry, etc.). *Potential exception: The author has observed elm (ring-porous) to be difficult to deaden via single ring girdling, however. Rathfon and Saunders (2012) also discovered that blackgum was more difficult to control as opposed to the high effectiveness of girdling applied to hickory and sugar maple. “Difficult” species will likely need more intensive measures (double girdling with herbicide) and have the treatment applied during the growing season (the 2012 study was performed in February). The study also indicated that the addition of herbicide sprayed into the single rings improved control of sprouting, which is highly beneficial when attempting to eliminate the targeted species’ ability to regenerate. For more difficult species being treated in the spring, a double ring girdle with herbicide applied in the top ring should be effective. Applications to lower rings in species with heavy sap flow (such as maples) may push herbicide out of the girdle if treatments are applied in early spring.
Girdling some species without the addition of herbicide may encourage sprouting, resulting in more labor required of the landowner. Species such as tree of heaven (Ailanthus altissima), black locust (Robinia pseudoacacia), Russian olive (Eleagnus sp.), Chinese tallow (Triadica sebifera), sassafras (Sassafras albidium), etc. are prone to sprout from the rootstock. As the reader may be aware, most of the aforementioned are invasive plants. In such instances, a herbicide is often required to adequately control infestations!
A counterpoint to herbicide uses in girdling applications is flashback. Flashback is the unintentional uptake of soil active ingredients (such as imazapyr or picloram) into adjacent non-target trees of the same species that may have grafted at the roots. It is likely that species with more accelerated growth rates, such as yellow-poplar and American sycamore (personally observed in these two species, in field settings by the author), have higher susceptibility.
Differing species do not appear to readily translocate herbicide to one another. Root grafting is common with trees of the same species in close proximity. In such instances, indirect uptake could be a potential issue. To help minimize the potential impact of herbicide, the applicator could reduce the amount of soil active herbicide and create a solution containing a non-soil active herbicide. This mixture should reduce the deleterious effect of flashback while also enabling a greater range of control of tree species being treated. An example would be imazapyr concentrate (Arsenal AC® or Polaris AC®) at 10% coupled with triclopyr amine (Garlon 3A®) at 50% of the solution mix, respectively. Harper (2020) suggests that this mixture is optimal for controlling both a greater range of species while minimizing the potential for flashback. Trees typically die within 3 – 4 months after treatment.
The land management practitioner must ultimately discern application delivery to individual stems within the stand to avoid unfortunate outcomes. For some species, avoiding soil-active herbicides (or at least reduced percentages in solution) may be necessary to avoid flashback. For others, such as the invasive root sprouts, herbicide use is strongly advised. Difficult species may require more than one girdle, with or without herbicide. Exercise safe protocol every time a chainsaw is to be in operation! Best of luck with your management endeavors.
References
Ballard, B. and Nowak, C. 2006. Timing of cut-stump herbicide applications for killing hardwood trees on power line rights-of-way. Arboriculture and Urban Forestry. 32(3): 118-125.
Clark, F. and Liming, F. 1953. Sprouting of blackjack oak in the Missouri Ozarks. Tech. Pap 137. USDA Forest Service.
Killroy, B. and Windell, K. 1999. Tree girdling tools. USDA Forest Service. 5E52E60 – small area forestry equipment. Tree Girdling Tools (fs.fed.us)
Noel, A. 1970. The girdled tree. Botanical Review. 36(2):162-195.
Rathfon, R. and Saunders, M. 2012. Midstory hardwood species respond differently to chainsaw girdle method and herbicide treatment. USDA Forest Service – Northern Research Station. Gen. Tech. Rep. NRS-P-117.
Wiant, H. and Walker, L. 1961. Variable response of diffuse and ring-porous species to girdling. Journal of Forestry. 59:676-677.
This article was originally featured in the Summer 2021 Version of CU in The Woods newsletter.
Author(s)
Stephen Peairs, Cooperative Extension, Forestry and Wildlife Specialist
This information is supplied with the understanding that no discrimination is intended and no endorsement of brand names or registered trademarks by the Clemson University Cooperative Extension Service is implied, nor is any discrimination intended by the exclusion of products or manufacturers not named. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.
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