Research Highlights

Summary

Forest managers use mastication to grind or shed vegetation competition, prepare a site for natural or artificial regeneration, or release sapling-sized trees or use mastication to convert ladder fuels to surface fuels and enhance decomposition of biomass. Determining the best mastication configuration within the context of management objectives and site limitations is challenging. USDA Forest Service scientists at the agency's Rocky Mountain Research Station prepared a general technical report that synthesizes their current knowledge on mastication as a forest management tool. They found that excavators, skid steers, and tractors can all be carrier machines and different types of vertical and horizontal cutting heads exist that can be front-end mounted or boom-mounted, each with its own advantages and disadvantages. The scientists provided a summary of the ecological effects of mastication. Although costs widely vary depending on machine size, the physical setting, size and configuration of pre-treatment biomass, and operator skill, mastication does have market and non-market benefits. Depending on the management objective, if mastication is an option, then a thorough site evaluation should consider slope, nonnative species invasions, vulnerability of soils to erode or compact, and treatment costs. There are a variety of cutting head and machine configurations that enable the use of mastication as a vegetation management tool. The more experienced the operator, the more cost-efficient the project will be, regardless of the configuration of the machine. Attributes that affect mastication costs include: tree diameter, site conditions, amount of biomass, and particle size requirements. Vegetation establishment is limited when the masticated mulch is deeper than 4 inches. Although mastication did not adversely affect the soils in these studies, good management practices (executing mastication on dry soils, driving on slash, deciding whether the machine needs to drive to each tree; or if a boom-mounted cutting head is desired) are preferred. All of these factors will help diminish soil scarification or compaction. Limited information on impacts to wildlife habitat exists. In general, wildlife species of concern and their habitat needs will determine if mastication will affect wildlife.

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