Forest degradation is one of the major factors contributing to a loss of global biodveristy and ecosystem integrity. Like many other forests in the West, the Deschutes National Forest is degrading public land in the name of restoration. One destructive activity they are currently implementing is the mystification of shrubs in the understory of trees. Mastication and mowing of shrubs are widespread on public lands across the West.
As with most forest management, the agency fails to disclose the qualifiers and limitations of its proposed forest management strategies.
According to proponents of mastication, mowing reduces fuels. These treatments are presumed to “return” the forest to natural conditions.
A web page on mastication lists the following questionable benefits.
The main benefits of forest mastication according to advocates are:
Wildfire reduction
Improvement of forest health
Improvement of wildlife habitats in high-fire-risk environments
The article asserts: “By removing shrubs or trees that overcrowd the forest, the remaining trees will no longer compete for soil nutrients, and healthy ground plants will have more direct access to sunlight. Mastication also leaves the soil intact while pulling up the roots of fire fuels. Additionally, forest mastication aids in the creation of fire-safe communities by greatly reducing the chances that wildfires will become catastrophic or life-threatening.”
The problems with mastication are typically not enumerated by the Forest Service. Let’s look at the above assertions.
WILDFIRE REDUCTION INEFFECTIVE
First, fuel reduction is seldom effective under extreme wildfire conditions. Why is this important? Because nearly all the acreage charred annually occurs during very infrequent but special weather/climate conditions. These conditions include drought, low humidity, high temperatures, and high winds.
If weather conditions do not enhance ignition, most wildfires go out without fire suppression. Since 99.9% of all fires occur outside these extreme fire weather conditions, most fuel reductions have limited influence on wildfire spread.
A second assumption behind fuel reductions is that a wildfire or ignition will encounter a fuel reduction when it is effective (I will return to this point below), but this is seldom the case.
That means most fuel reductions do not influence wildfire, but we (and the forest ecosystem) get the associated impacts.
A third questionable assumption is that mastication will return a forest to its “natural conditions.” Most of all, plant communities in the West are in their natural conditions.
The presumption that fire suppression has altered the natural fire regime of nearly all plant communities is factually inaccurate. Most plant communities have mixed to long fire rotations, often hundreds of years, and are within their historical condition.
Mastication often leads to replacing shrubs like chaparral, snowbrush, or bitterbrush with grasses, which are more flammable than the shrubs. Unless one continues mastication and mowing every year or two forever, you realize no benefit.
Mastication also chops fuels into smaller pieces which dry out quicker and more easily ignited.
IMPROVEMENT OF FOREST HEALTH QUESTIONABLE
The starting assumption is that reducing plant density creates a “healthy” forest that is more “resistant” to insects, disease, drought, and wildfire. Ironically, killing trees and shrubs with machinery is not considered detrimental. Yet there is abundant ecological evidence that natural processes like wildfire (drought, insects, and disease) are evolutionary factors critical to ecosystem health.
Many plants and animals depend on dead trees for their habitat. Down logs are used by many small mammals, amphibians, and reptiles for food and shelter. Standing snags are essential nesting and foraging sites for birds and bats. When logs fall into a stream, they are critical for fish habitat and an essential structural component of the waterway.
Given that mechanical removal of specific trees or shrubs is an artificial selection process that does not mimic the evolutionary and genetic processes from natural processes like insects, drought, disease, and wildfire, rather than improving “forest health” forest management, including mastication DEGRADES plant communities.
All of these natural factors are critical to ecosystem health. They are not processes that should be limited or suppressed.
The idea that a reduction of fuels will reduce mortality, neglects to count the number of trees killed by the mastication process. Many young trees are destroyed, which alters the age structure of the stand. This can have negative consequences because some natural mortality sources are age-dependent.
For instance, bark beetles usually attack larger trees. But if mastication has removed the small trees, you don’t have that younger age class to replace the trees killed by bark beetles.
CLAIMS THAT MASTICATION, THINNING, AND PRESCRIBE BURNS IMPROVES WILDLIFE HABITAT DEPENDS UPON WHICH SPECIFICS CONSIDERED
Removing fuels or reducing plant density to improve wildlife habitat is one of those generalizations that requires qualification.
If you are a woodpecker looking for a snag with bark beetles, removing such snags does not “improve” wildlife habitat. If you are a fish in a river that needs a log to slow the current, tree removal does not improve the habitat. Mastication does not improve wildlife habitat if you are a mule deer that needs bitterbrush or other shrubs for winter food.
Such statements are species-specific. Wildlife species that benefit from forest manipulation can be termed “generalists” because they are adapted to various habitats, including forest stand alterations.
Given the enormous amount of landscape that is typically manipulated on public and private lands, one can question whether we need more forests or plants favored by generalist species.
To the degree that any mastication occurs, it should be strategic, immediately adjacent to homes and communities, and limited to areas where it can be maintained year after year with the realization that, in all likelihood, it will not preclude the spread of a wildfire under extreme fire weather conditions.
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