Forestry mulching

File:Mulching machine in wetlands.jpg

Purpose-built tractor with mulching attachment being used in wetlands

Fecon mulching attachment on a Sennebogen excavator, being used to clear roadside brush in Germany

Hydraulic-powered mulching attachment on rubber-tired tractor

PTO-driven forestry mulching attachment on an agricultural tractor

Forestry mulching attachment on a Bobcat skid steer

Examples of chipper tools ("teeth") available on forestry mulching attachments

Forestry mulching is an approach to land clearing that employs a machine to simultaneously cut, grind, and clear vegetation with limited disturbance to soils or desirable vegetation.

A forestry mulching machine (“forestry mulcher”) uses a rotary drum equipped with steel chipper tools (“teeth”) to shred vegetation. They are manufactured as application-specific tractors and as mulching attachments (“mulching heads”) for existing tracked and rubber-tired forestry tractors, skid steers, or excavators.

Heavy duty forestry mulchers can clear up to fifteen acres of vegetation a day depending on terrain, density, and type of material. Forestry mulchers are a popular choice within land clearing, right-of-way, pipeline/power line, wildfire prevention and management, vegetation management, invasive species control, and wildlife restoration markets.

Issues with traditional land clearing methods

Conventional land clearing methods require several machines and multiple steps, often including a bulldozer accompanied by some combination of excavators, tree shears, wood chippers or grinders, and hauling equipment.

Bulldozing clears land by forcing trees, brush, rocks, and dirt completely up out of the ground. The resulting piles of debris (windrows) must then be raked, sorted, and either hauled away, dried and burned, or otherwise disposed of.

According to WNCGreenBuilding, some additional issues with traditional land clearing methods include:

• Required permitting and site plan
• Damage and dislocation of topsoil layer
• High ground pressure (compaction)
• Erosion control (silt fencing and catch basins)
• Highly weather dependent machinery operation
• Resulting brush piles and debris
• Damage to nearby trees and vegetation

Benefits of forestry mulching

By processing trees and other vegetation where they stand, mulching machines eliminate many of the non-value added steps (site prep, cutting/felling/hauling, and site cleanup) to clear land faster and more cost effectively. The inherent elimination of residual waste and brush piles turns scrubby, overgrown, and unusable land into usable or marketable real estate without any burning, hauling, or dumping costs to the operator or environment. Because one mulching machine does all the work, jobsite fuel requirements and emissions are also decreased. That means less fuel and emissions from hauling equipment to the job site and hauling material and equipment away.

Highly selective management of vegetation

Mulching machines are capable of clearing land of unwanted trees and brush without destruction to the property or surrounding “keeper” trees. The maneuverability of a mulching attachment on a properly selected carrier makes it ideal for selective thinning around structures or to create desired spacing without damaging remaining trees.

Overcome adverse conditions

Some mulching machines also have the ability to operate on steep slopes and in small or tight areas, in poor ground conditions, and in wet or snowy weather. Depositing mulch in wet or swampy areas helps to dry up the ground so other equipment can gain access.

Environmental benefits

Traditional land clearing methods often present an increased risk of erosion by pushing over trees, uprooting the stump and roots, and substantially disturbing soils. In contrast, mulching the vegetation leaves the soil structure intact. The mulched material can be left on the ground and will act as an erosion barrier while returning nutrients back into the soil through decomposition. Over time, grass will naturally grow through the mulch and can be maintained with mowing.

Applications of forestry mulching

Some specific vegetation management applications for forestry mulching include, but are not limited to:

Right-of-way clearing and maintenance

Forestry mulching is used in the right-of-way clearing and maintenance for roads, highways, pipelines, and other utility lines. This process often requires complete removal of standing trees, stumps, and vegetation. Ensuring a safe flow of traffic along these lines is a critical and ongoing component requiring unique treatment.

According to industry experts at Fecon, Inc., “machinery selection for right-of-way jobs can be varied. Compact tractors with mulching heads can do fence line work, detail work, and can handle even the heavier grasses found on right-of-way property. For thinning work, tree shear attachments or excavator mounted mulchers may offer the best solution [for] selective cutting between the keeper trees. For large scale projects where volume of work is the key factor, larger tracked mulching tractors will yield both a workable finish and the greatest acreage per day for maximum productivity.”

Land clearing

Forestry mulchers can be used in a wide range of commercial and residential land clearing projects. Site prep and development, cutting and clearing brush, nature and recreational trail creation, and seismic exploration are some common land clearing uses of mulching machines.

Experienced land clearing contractors will usually approach the job with multiple pieces of equipment, including tracked mulching machines, excavator mulchers, and skid steer tractors equipped with mulching attachments. Residential or urban interface projects could utilize smaller and lighter tracked mulching tractors effectively on softer ground conditions or where more detailed work is required. A variety of undercarriage specifications help keep the machine moving and can reduce the ground disturbance while offering the production rates needed.

Wetlands and riparian habitat conservation

Forestry mulching has become popular among nonprofit riparian conservation organizations, government agencies, hunt clubs, and private land owners in attempts to maintain habitats for pheasants, doves, elk, deer and various other animals. Maintaining an animal habitat encompasses several different aspects: food, water, shelter, and space, and there are many products that can help reclaim and maintain wildlife habitats for these animals.

• Food: Forestry mulchers and forestry mowers are often used for removing underbrush and invasive species, such as buckthorn and multiflora rose, allowing sunlight into the understory and the rejuvenation of grasses and other food sources.

• Water: In addition to food sources, water source access can be obstructed or become stagnant due to tree and understory growth. Forestry mulchers and tree shears are well equipped for removing trees and underbrush from waterways, allowing animals to access the water source. Mounting these attachments on an excavator allows you to reach into the waterway, creating minimal ground and habitat disturbance while removing the unwanted vegetation.

• Shelter and space: Many animals require certain criteria for shelter, breeding, escaping the summer heat, and protecting themselves from the cold temperatures of winter. Pheasants, for example, require clump forming grasses and cattails for breeding and protection during the winter months. Invasion of underbrush can force out the grasses required by these birds for breeding, just as invasive willows can restrict the growth of cattails required for the bird’s protection during the cold winter months. Targeted removal of these invasive species can be accomplished with a variety of mulching attachments.

Invasive species control

Some common invasive plant species such as tamarisk (salt cedar), Pinyon-juniper (pj), Russian olive, buckthorn, and multiflora rose can invade a natural habitat, soak up a tremendous amount of ground water, and need to be removed to reestablish the native habitat or to preserve the water table. Invasive insects such as pine beetles can also devastate forests, leaving behind rotting trees with diminishing timber value and that may become falling hazards if they lose their ability to stand up against wind.

Proactive mulching is an ideal means of reducing stress on trees caused by crowding, making them less susceptible to attack from invasive species. If already affected by invasives, however, mulching in place controls spread of invasive plants, insects, and fungus. The mulching action tends to discharge the material downward and within a reasonably confined area, versus other methods such as rotary cutters that may laterally disperse pine beetles or other invasives into neighboring healthy trees. The mulching process exposes these invasive species to the elements — where they are no longer protected by tree and will struggle to survive — and eventually allows for the re-introduction of native vegetation and grasses into the area.

Wildfire prevention and management

• Proactive mulching: Mulching reduces the potential for wildfires by eliminating small leafy plants and mulching fallen or rotten trees. If left untreated, these fuel loads increase potential for fire, increase the heat intensity, and serve as fire ladders that enable fire to elevate quickly to the tops of trees which is where a fire can spread most quickly. Mulching can also be used to create a coarse grind finish that can create a more ideal controlled burn. There are many options for fuel mitigation and underbrush removal including tracked forestry mulching machines, mulching attachments, and tree shears. Proper clearances and fire breaks are created around homes that border the forests to create defensible space for the communities.

• Reactive mulching: In addition to proactive thinning of vegetation to mitigate fire fuels, forestry mulching can be used for reactive cutting of lines (fire breaks) on active fires. When a bulldozer pushes trees out of the way to clear a fire line, it leaves a mess in its wake that needs to be attended to after the active fire control operations are completed. Large mulching machines have a massive mulching capability and can mulch material directly into the ground to prevent leaving flammable material behind. Larger forestry mulchers leave minimal clean up requirements and can help reduce the overall costs of active fire mitigation.

• Cleanup: After the fire is out and cleanup efforts are under way, it is important to ensure minimal water pollution and soil erosion. Tracked forestry mulching machines, mulching attachments, and an excavator with a mulching attachment can provide a top layer of mulch to prevent soil erosion on slopes and minimize water pollution.