Herbicides in the Context of the MRC Mission
Mendocino Redwood Company (MRC) continues to demonstrate that it is possible to restore depleted forestlands as part of a viable business plan. With the mission to return its forests to a healthy ecological balance, MRC uses herbicides to promote redwood and Douglas-fir and retard tanoak, a native hardwood, along with non-native invasive vegetation. Such restoration is technically challenging. It will take many years to return MRC forests to their historically natural condition.
Past Issues Challenging Today's Forest
MRC has had to play "catch up" in order to grapple with forest conditions that we inherited from previous land owners and past land use. In the early part of the 20th century, persistent burning to convert forests to pastures produced thousands of acres of grass and brush. Tanoak was often the first and only tree species to reoccupy these sites when they reverted back to forest. Once disturbed by cutting or burning, tanoak trees sprout aggressively; they rapidly overtake conifer seedlings and suppress regeneration of the redwood and Douglas-fir forest. Adding to the problem was the past practice of "high-grading"--removing the best conifer trees from a forest and leaving only smaller ones along with the tanoak. This allowed tanoak to out-compete the conifers and become the dominant tree species.
Current Uses of Herbicides
As part of its forest restoration, MRC uses herbicides applied manually on a plant-by-plant basis. Manual application of herbicides includes both foliar and frill treatments. In a foliar application, a competing tanoak tree is cut down. A year or two later, MRC applies a chemical and water mixture to its stump sprouts. Frill, on the other hand, entails cutting through the bark of the tanoak and applying herbicide to its cambium layer; this thin formative layer is where the tree moves water and food between its top and its roots. MRC also uses herbicides to contain non-native invasive weed species or to retard vegetation emerging after a forest fire.
MRC use of herbicides is regulated by the Mendocino County Agricultural Commissioner and monitored by the Regional Water Quality Control Board. We require contractors employed for vegetation management to use protective gear and to confine application of herbicides during appropriate weather conditions. MRC follows strict guidelines that not only meet but often exceed government regulatory requirements. In addition, MRC uses techniques suggested by The Nature Conservancy's Weed Control Handbook.
Early MRC Targets for Herbicide Reduction
In 2000, MRC set an ambitious target to reduce its use of herbicides by at least 60% over 4 years. While this goal was not completely achieved, MRC did reduce herbicide use by 44% in 2000-2002 and by 48.5% in 2003. Starting in 2001, MRC began reducing its use of a specific chemical brand, Garlon, by 90%. In each successive year, MRC exceeded its specific commitment for Garlon reduction. All the while, MRC has continued to look at ways to reduce its need for herbicides. We have tested and monitored several alternative methods including eucalyptus oil, neem oil, and wheat gluten. So far, however, these alternatives are not as effective and are more costly than the selected herbicides.
In some stands where tanoak is less pervasive and the conifer has become the dominant tree species, MRC uses chainsaw cutting to keep tanoaks in check. It is likely that this method of control will be continued in these stands as an effective, non-chemical treatment for tanoak control.
Going Forward
In the future, our annual herbicide use may vary depending on the level of harvest and which stands are chosen for restoration. Without a doubt, the trend for herbicide use is downward as MRC gradually brings forest stands back to the preferred balance of conifers and hardwood.
Moreover, in keeping with Forest Stewardship Council principles, MRC is committed to phasing out the use of chemical herbicides as a routine management tool and transitioning to silvicultural regimes which require little or no herbicides to ensure conifer survival and growth. MRC foresters closely evaluate each forest stand before and after harvesting to determine if and where herbicides are required. By monitoring past levels of herbicide treatments, MRC can calibrate and limit future treatments.
To better understand its future herbicide needs, MRC has also turned to computer technology. Several years ago, MRC developed a Landscape Planning Model to predict forest inventory, growth, and harvest over a 100-year period. In 2003, MRC developed yet another computer model that uses harvest outputs from the Landscape Planning Model along with estimates from MRC foresters on the application rates of herbicides. Taken together, this information assists MRC in estimating future herbicide requirements. With such tools, MRC continues to refine its herbicide application.
Rationale for a Flexible Approach
From past experience, MRC has learned that it is currently unrealistic to exclude herbicides as a management option, given the state of its forests today. Nevertheless, MRC is committed to exploring alternatives for herbicides and to targeting herbicides only for vegetation that detrimentally competes with redwood and Douglas-fir forests. Until better solutions become available that are practical, environmentally suitable, and economical, MRC will responsibly use herbicides in very limited and controlled ways: (1) to restock conifer stands previously impacted by hardwood competition; (2) to promote conifer growth where there has been no effective vegetation management; (3) to foster conifer growth where it is being retarded; (4) to contain non-native invasive weed species; and (5) to conduct experiments that could further reduce herbicide use.
|
