Trees
High
Moderate–high ($1000–$5000/gross)
Low risk
High risk
Low/no risk
Moderate (wildlife, habitat)
Overview
Chainsaws are typically used to control woody plants with large stem diameters. They are used by professionals and private landowners to fell trees, but not by volunteers because they require a high level of training and skill to operate safely.
In California, large established stands of tree-of-heaven or eucalyptus are often targeted species (although resprouting species such as these require follow up work). In the Modoc Plateau region of California, junipers are often targeted where range and shrublands are easily invaded by trees in the absence of disturbance by fire. Chainsaws can be used to cut down virtually any kind of aboveground woody biomass. Multiple return visits will be necessary on plants that have the capacity to re-sprout for control to be achieved.
Numerous sizes and styles of chainsaws are available, with various advantages to each. Larger saws may be needed for large vegetation but saws with 12-14” bars are suitable for most invasive plant control. Smaller saws are lighter and are often preferred by users to limit fatigue over a long day of work. Large invasive tree removal may require larger heavier saws with bar lengths ranging from 18 to 40 inches.
Most chainsaws are gas-powered, but some are electric. Gas chainsaws have two-stroke engines which require a high-octane gas mixed with oil (typically at a 50:1 ratio - read your tool’s manual and follow fuel recommendations for optimum performance). Though more powerful, gas chainsaws emit fumes such as benzene and carbon monoxide that can be harmful to the environment and to workers. They are also loud. Electric chainsaws are either corded or battery powered. Battery powered electric saws are typically smaller and less powerful than corded options, but they are lightweight compared to most gas-powered saws and are thus easier to carry to remote locations. However, smaller battery-powered chainsaws are limited by battery capacity, and extra batteries can be very heavy. Lithium batteries generally last longer than nickel cadmium (NiCd) batteries.
How to Use
When using a saw, it is important to maintain proper chain tension and sharpness. Adjusting the tension of the chain should be done when the saw is cool. The chain should feel snug, but still move freely: a chain that is too tight can cause damage to the equipment. A chain that is too loose can pop off the bar during use, and cause damage to the saw or injury to the user. The teeth on the chain should be sharpened regularly with the proper file, as a sharp chain will increase the effectiveness of the cut and reduce wear on the drive system. It is important to let the saw do the work, and not force the saw into the cut. Keeping the chain out of dirt and rocks can be difficult while making cuts flush with the ground but is essential to maintaining sharpness. Sparks from the chain hitting rocks in the soil is a safety hazard during wildfire season (summer and fall) and should be avoided at all costs. Fire extinguishers should be on site during felling operations, and fire risk plans should be in place.
Chainsaws can be used to cut woody vegetation at the ground level. In order to utilize the saw safely, there needs to be access to the main stem, and room for maneuvering around the vegetation. Trees and shrubs which have branches low to the ground may need to be trimmed back in order to create a safe space to initiate the cut of the main stem. Every saw has a chain brake to stop the chain from moving, and it is important to use the chain brake whenever a cut is not actively being made. Using a chainsaw can be dangerous without training, and it is important when cutting large woody vegetation to use proper cutting technique, such as front cuts, holding wood, and wedges. Use of these tools and techniques are not described in this publication, because they should be leaned through sawyer instruction courses.
Woody vegetation can be targeted with a chainsaw at any time of the year, given environmental conditions that allow safe use of the machinery. Typically, coniferous woody vegetation (such as pine, juniper, or cypress) will not sprout after cutting and can be effectively controlled at any time of the year. When cutting coniferous species, it is important to cut the stem below any green vegetation to eliminate the potential of new growth.
Deciduous species are more likely to send up sprouts from roots or stump following the main stem being cut. Shoots from cut stumps can grow into new trees or bushes and can continue to produce seeds. Shoots can grow from stumps, root collars, or from root buds many feet away from a stump. It is important to conduct follow-up treatments to control these shoots either by cutting, tarping or herbicides. If cutting is chosen, shoots must be cut multiple times per year, for multiple years, in order to exhaust the root system of energy. In some cases targeting deciduous tree species before the dry season can reduce the vigor of regrowth.
Biomass from cut vegetation can be handled in different ways. Woody biomass can be left on site, piled and burned, chipped, or removed from the location. Different techniques vary greatly in cost and labor and must be considered during the planning process. Your biomass strategy will depend on assessments of factors including fire risk, impact on re-establishment of desirable vegetation, and aesthetic impact on visitor experiences.
Follow all maintenance and operational recommendations for equipment. Regardless of power source, all chainsaws require bar oil to provide lubrication during cutting. Running a saw without bar oil can damage to the equipment. It is important to regularly take apart and clean the saw to maintain proper function. See “Potential Hazards” for more information on safety precautions. Tree pathogens may also be spread by chainsaws and other tree pruning equipment. Clean and sterilize equipment after a job and before using equipment on desirable vegetation. Seventy percent alcohol, bleach solutions or Lysol, can all be used to disinfect the equipment from pathogens.
Special Tips
Chainsaws can be used in conjunction with other techniques and are often part of an integrated pest management (IPM) approach. For stumps that send up sprouts after cutting, physical barriers such as thick, dark tarps can be used to cover the stump and reduce growth. Tarps and the surrounding area need to be monitored to ensure sprouting does not occur. For stump sprouting species, it may be of increased benefit to dig a hole around the stump and recut the stump below the soil surface. Covering the cut stump with a barrier and burying the stump and barrier should inhibit sprouts from the stump (see Tarping BMP).
For stumps left uncovered, cutting the regrowth from stumps and roots needs to be conducted multiple times a year for multiple years. Chainsaws may not be the best tools to cut regrowth less than 3-4 inches in diameter. Loppers, saws, hedge trimmers, reciprocating saw, or brush cutters may be more appropriate for smaller shoots. For shoots that sprout around the stump from existing root stock, mowing with various equipment may be most appropriate to suppress growth.
Chainsaws can also be used to facilitate other treatment methods by removing excessive biomass. Biomass removal can provide access to roots and rhizomes which can then be removed using hand tools. This technique works well on large grasses such as jubata grass (Cortaderia jubata) and giant reed (Arundo donax). Additionally, maintaining low vegetation cover at a project site can facilitate follow-up treatments for species where consistent follow-up is critical, such as Cape ivy (Delairea odorata).
Battery-powered reciprocating saws are another useful hand tool for invasive species control. While not as powerful as chainsaws, reciprocating saws are often lighter, more portable, and generally require less training for safe operation. Smaller diameter woody stems, or the crowns of invasive grasses, can be effectively cut using a reciprocating saw. Multiple batteries will be needed for all day use.
Optimal Conditions for Use
Chainsaws can be used effectively under both dry and wet conditions. Large woody vegetation generally recovers quickly after cutting in wetter climates, and so frequent cutting and control efforts may be required in wet areas. Most woody species in dry areas do not grow as quickly as vegetation in wet climates, so control efforts may not need to be as frequent. For some woody species,cutting before the dry season reduces the amount of sprouting from the root and stump.
Caveats
Cutting resprouting species a single time will not provide adequate control and may make the problem worse. Careful planning for follow-up treatment of suckers is essential.
By removing large woody vegetation one opens the canopy andnewly available light resources may encourage invasive species colonization. Secondary invasions should be anticipated during the management planning process.
The growth form of the target species should also be considered during the planning phase and should be matched to the skill and training of the sawyers tackling the problem. Large trees on steep slopes generally require more skill and training to cut safely. Additionally, multi-stemmed branching species are more difficult to cut than single stemmed or straight stemmed species. Sawyers should not work alone and should be in radio contact with other crew members in case an injury occurs during the felling process.
When treating woody vegetation, there must be adequate resources to deal with the biomass generated, especially when treating and dealing with large trees. In essence, removal may need to be treated as a logging operation, even if there is not economic value to the woody vegetation being removed. Removal of the biomass by off-site chipping, on-site chipping, or piling and burning are some of the options that can be utilized. However, almost all methods from biomass removal to burning increase the opportunity for disturbance on the landscape being treated. From skid trails to burn marks, it may be necessary to follow up with additional treatments to reduce secondary invasion or species replacement. Restoration plantings and follow-up control may be required to ensure desirable vegetation takes hold in these disturbed areas.
Operation of chainsaws in a wildland setting often means bringing gasoline, oil and bar oil into the field, which can be hazardous to water quality and the natural environment if spilled. A tarp or similar non-permeable surface should be used to contain spills while refueling your chainsaw. A spill kit should be on-site or nearby to quickly address any accidental spills.
Potential Hazards to Humans, Environment, and Cultural Resources
Human safety: High risk. Chainsaws can be very dangerous to use, and proper training and personal protective equipment is needed for all users. This cannot be overstated. There is no substitute for hands-on chainsaw safety training prior to use of the tool. Vibration absorbing gloves, protective eyewear, hearing protection, and chainsaw chaps should all be used. Direct severe physical injury from the saw or chain is possible, even to experienced sawyers. Injury can also occur from large woody vegetation that is being cut. Trees can fall in an unintended direction or fall off of their base unexpectedly if cut improperly. Chainsaw users must understand forces of tension and compression to predict how trees will react to different cuts. It is always important to have clear footing and an unobstructed path of escape while cutting. Fuel exhaust from gas-operated chainsaws is also hazardous and exposure should be limited to the degree possible.
Cultural resources: Low risk. In general, cultural resources should not be impacted by the use of chainsaws. Care should be taken to avoid contact of the chainsaw with anything other than the non-desirable vegetation. Falling trees can potentially damage aboveground cultural resources, if present. Precautions should be taken when cutting to ensure the felled vegetation will not contact or damage such resources. Additionally, in some locations, non-native trees may be considered historic resources (e.g. eucalyptus windrows on historic ranches). Tree removal in these situations should be coordinated with cultural resource specialists.
Habitat: Moderate risk. Animals living in target trees (such as birds, bats, and squirrel.) may be harmed by cutting Trees should be checked and nesting bird surveys should be conducted before cutting during breeding season (generally Feb 1- Aug 31) to minimize damage to nests. Do not cut trees that contain active nests.
Sensitive plants: Low risk. Identify sensitive plants in the treatment area in advance and avoid trampling or otherwise impacting them.
Erosion: Low risk. There is little risk of increased erosion immediately after woody vegetation is cut. Stumps and roots are typically left in place after cutting. However, there can be a risk for increased erosion especially on steep slopes if other vegetation does not colonize the site before large rain events. Likewise, techniques used to deal with cut biomass, such as slash pile burning or removal or mulching using large equipment, may increase the potential for erosion. If erosion-prone conditions are created during treatments, logs and slash from the tree removal can be used to build erosion control structures.
Fire: Moderate risk. Using gas-powered equipment can cause sparks, so users should follow all local fire prevention guidelines and restrictions when operating chainsaws. Care should be taken to remove dead and dry materials around the trees, and fire extinguishers or water sources should be available at the cutting site.
Consider Combining with the Following Non-Chemical Methods
Follow up treatments of stumps after trees are cut with a chainsaw is often needed. Tarps or other physical barriers can be secured over the stump in order to prevent re-spouting from occurring (see Tarping BMP). Follow-up control of sprouts with cutting hand tools, brush cutters, or other stem removal techniques may be required if herbicides are not utilized. Excavations of woody stumps will be more feasible once the aboveground biomass has been cut. Stumps can be ground down after cutting to prevent resprouting (see Grinding BMP).
Don’t Use This Technique When/For
Using a chainsaw to control woody vegetation that sends up stump or root sprouts will not be effective if secondary sprouts are not planned for and controlled. Cutting the main stem will reduce seed set and greatly suppress the plant, but It is important to follow up with secondary cutting treatments for sprouts and suckers. Sprouts may need to be cut multiple times a year for many years to kill or suppress the root system of the tree. In certain climates, suckers must be treated monthly to prevent root system recovery. If sprouts are not controlled, cutting an individual stem or trunk may lead to further spread through generation of sprouts forming off the auxiliary roots. Adequate funding for follow up treatments and monitoring should always be part of the initial control plan.
References
Bates, J.D., T. Svejcar, R. Miller, and K.W. Davies. 2016. Plant Community Dynamics 25 Years after Juniper Removal. Rangeland Ecology and Management, 70(3): 356-362.
Miller, J.H., S.T. Manning, and S.F. Enloe. 2015. A Management Guide for Invasive Plants in Southern Forests. USDA Forest Service Southern Research Station. General Technical Report SRS-131.
Oneto, A.R., G.B. Kyser, and J.M. DiTomaso. 2010. Efficacy of Mechanical and Herbicide Control Options for Scotch Broom (Cytisus Scoparius) and Cost Analysis of Chemical Control Options. Journal of Invasive Plant Science and Management. Vol. 3, Issue 4, pp. 421-428.
Spinelli, R., L. Pari, G. Aminti, N. Magagnotti, and A. Giovannelli. 2017. Mortality, Re-Sprouting and Physiology of Coppice Stumps after Mechanized Cutting. Annals of Forest Science 74:5.
Authors and Credit
Lead Author:Tom Getts, University of California Extension Weed Advisor, UC ANR
Co-authors:
Pamela Beitz,
Integrated Pest Management Specialist, East Bay Regional Parks District
Dan Lubin, Environmental Scientist, California State Parks
Tom Reyes, Integrated Pest Management Coordinator, Midpeninsula Regional Open Space District
Additional Contributors:
Joan Miller
(volunteer), Laguna Canyon Foundation
Ken Moore, Wildlands
Restoration Team
Efficacies
| Rating | |||
|---|---|---|---|
| Plant | Flowering Period | ||
| Winter | Good | ||
| Spring | Good | ||
| Summer | Good | ||
| Fall | Good | ||
| Multiple Seasons | Good | ||
| None | Good | ||
| Plant | Germination | ||
| Winter | Good | ||
| Winter / Spring | Good | ||
| Spring / Summer | Good | ||
| Opportunistic | Good | ||
| Plant | Palatability | ||
| Yes | No Information | ||
| No | No Information | ||
| Partial | No Information | ||
| Plant | Plant Growth Form | ||
| Grass | N/A | ||
| Forb | N/A | ||
| Shrub | Good | ||
| Tree | Good | ||
| Vine | Fair | ||
| Plant | Plant Type | ||
| Annual | N/A | ||
| Biennial | N/A | ||
| Perennial | Good | ||
| Plant | Propagule Production | ||
| Low (<1000/square meter) | Good | ||
| Moderate (1000–10,000/square meter) | Good | ||
| High (>10,000/square meter) | Good | ||
| Plant | Rate of Spread | ||
| High (doubling in <10 year) | Fair | ||
| Moderate (50–75% increase in 10 years) | Good | ||
| Slow Rate (25% increase in 10 years) | Excellent | ||
| Plant | Resprouting / Regenerative Capacity | ||
| Low | Excellent | ||
| Moderate | Good | ||
| High | Fair | ||
| None | Excellent | ||
| Plant | Seed Life | ||
| Short (≤3 years) | Good | ||
| Moderate (4–10 years) | Good | ||
| Long (>10 years) | Fair | ||
| Plant | Type of Reproduction | ||
| Seed | Excellent | ||
| Vegetative | Fair | ||
| Seed & Vegetative | Fair | ||
| Plant | Type of Vegetative Reproduction | ||
| Rhizome / Stolon / Stem | Ineffective | ||
| Bulb / Corm / Tuber | Ineffective | ||
| Root sprout / Sucker / Crown sprout | Poor | ||
| Site | Existing Desirable Plant Cover | ||
| <10% | Excellent | ||
| 10–25% | Excellent | ||
| 26–50% | Excellent | ||
| 51–75% | Good | ||
| >75% | Good | ||
| Site | Ground Condition | ||
| Muddy | Good | ||
| Smooth | Excellent | ||
| Cobbly | Good | ||
| Rocky | Good | ||
| Site | Habitat | ||
| Marsh / Wetland | Good | ||
| Riparian | Good | ||
| Grassland | Good | ||
| Shrubland | Good | ||
| Woodland / Forest | Excellent | ||
| Site | Level of Tolerable Disturbance | ||
| Low | Fair | ||
| Medium | Good | ||
| High | Good | ||
| Site | Slope | ||
| Flat | Excellent | ||
| Moderate (10–40%) | Excellent | ||
| Steep (>40%) | Fair | ||
| Site | Target Area | ||
| <40 square feet | Excellent | ||
| 0.001–0.01 acre | Excellent | ||
| 0.02–0.1 acre | Excellent | ||
| 0.2–1 acre | Excellent | ||
| 2–10 acres | Good | ||
| 11–50 acres | Good | ||
| 51–100 acres | Fair | ||
| >100 acres | Fair | ||
| Site | Targeted Invasive Plant Cover | ||
| <1% | Excellent | ||
| 1–10% | Excellent | ||
| 11–25% | Excellent | ||
| 26–50% | Good | ||
| 51–75% | Good | ||
| >75% | Good | ||
| Site | Vehicle Accessibility | ||
| Roadside | Excellent | ||
| <100 feet from road | Excellent | ||
| 100–1000 feet from road | Good | ||
| >1000 feet from road | Fair | ||
