Introduction to Physical Control – Cutting
Cutting or mowing of woody invasive plants involves severing the trunks or stems of target plants near the soil surface. Single instances of cutting are not effective for controlling woody invasives due to the ability of almost all of these species to regrow from stumps and the root system. Frequent repeated cutting can decrease invasive populations, though the frequency and duration of cutting is often unknown not known with precision (though is both are generally presumed high) and likely vary by species and age of plant. Cutting can improve access to implement other control strategies or as a component of the cut-stump herbicide application method.
How it works
Cutting a woody invasive plant at the base of the stem instantly severs the connection between the photosynthesizing parts of the plant and the roots. However, cutting does not damage the belowground plant parts, and most woody invasive plants store enough energy belowground to regrow.
Methodology in Detail
Plants can be cut at any time of year, though cutting prior to fruit production is ideal to spread of seed.
It may be possible to kill certain large tree species with a single instance of cutting if they are not able to produce new leaves fast enough to feed large root systems. In particular, cutting has proven effective on large Norway maples, but not on smaller individuals (Webb et al. 2001). Other large trees that are not known for vigorous root sprouting may also be good candidates.
While all woody invasive species should be expected to regrow from the root crown where the stems are severed, certain species sprout from the entire root system, particularly in response to damage. Cutting as a stand-alone practice may increase the density of the infestation of these species and is not recommended. Woody invasives known for aggressive root sprouting in response to stem damage include black locust, white poplar, tree-of-heaven, Russian olive and Oriental bittersweet.
The equipment used for cutting above-ground growth will depend on overall project budget, size of the project site, species being treated, average size of individuals being treated, density of the infestation, and availability of skilled and insured labor. For relatively small projects or for projects of any size utilizing volunteer labor, cutting is likely to be accomplished using non-powered hand tools. Small woody stems can be cut with heavy-duty bypass loppers. Larger stems – up to 6” in diameter at breast height – can usually be cut with a non-powered forestry saw (Forest Preserve District of Cook County 2014). For projects with larger diameter stems, skilled laborers typically use power tools such as hand-operated clearing saws/brush cutters and chain saws, forestry mowing equipment, or even commercial timber harvesting equipment. All cutting equipment should be maintained and sharpened according to the guidance of the manufacturer.
The amount of personal protective equipment for cutting woody plants depends on the equipment being used. For non-powered tools, leather gloves and sturdy boots may be sufficient, though a hard hat provides additional protection if cutting taller plants. Clearing saws/brush cutters are the least hazardous power tool for cutting relatively small stems because the long handle holds the blade away from the operator when in use. The U.S. Forest Service recommends that operators wear leather gloves and boots, forestry chaps, hearing protection, safety glasses, and a hard hat with a face screen when using clearing saws (Trent 2006). Chainsaws and any vehicle mounted cutting machines or attachments are inherently dangerous pieces of equipment. Operators should follow OSHA training and PPE recommendations for these tools.
The goal of cutting shrubs or trees is to sever the trunks or stems parallel to and as close to ground level as possible, bringing all above-ground portions of the plant down. Trees, large shrubs, or limbs that are left leaning on surrounding trees are extremely dangerous and must be avoided (Stelzer 2017). Stumps that are not cut short enough or that are cut at an angle can pose trip and impalement hazards (Forest Preserve District of Cook County 2014). When cutting large vines that have climbed up trees, it is safest to leave the severed vine hanging where it will dry out and degrade (Gover 2013).
Regardless of equipment being used, there should be a slash/debris management plan in place before cutting begins (see the WIGL Collaborative guide on disposal of invasive plant material).
If invasive plant seeds are likely present on site (e.g., the plants being cut are fruiting or have fruited previously), all equipment and operator clothing and footwear should be cleaned before leaving the site to prevent spreading invasive plant seeds to new locations.
Any invasive species treatment needs to be monitored in the years following treatment. Regrowth should be anticipated for multiple years following the cutting of any woody invasive species.
- Forest Preserve District of Cook County. 2014. Managing invasives.
- Gover, A. 2013. Exotic woody vines. Penn State University, Department of Plant Science. Invasive Plant Species Management Quicksheet 9.
- Miller, JH, Manning, ST and SF Enloe. 2015. A Management Guide for Invasive Plants in Southern Forests. United States Department of Agriculture, Forest Service, Southern Research Service. SRS-131.
- Stelzer, H. 2017. Felling, limbing and bucking trees. University of Missouri Extension. Publication G1958.
- Trent, A. 2003. Brush-clearing head evaluation. Tech Tip 0324–2336–MTDC. Missoula, MT: U.S. Department of Agriculture, Forest Service, Missoula, MT.
- Webb, SL, Pendergast IV, TH, and ME Dwyer. 2001. Response of native and exotic maple seedling banks to removal of the exotic, invasive Norway maple (Acer platanoides). Journal of the Torrey Botanical Society. 128(2): 141-149.
Photo Credit: Michigan Department of Natural Resources