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for
Coconino National Forest
Southwestern Region
U.S.D.A. Forest Service
This is a proposal to eradicate small reinvading juniper through the use of a selective herbicide. Through small sample plot testing the herbicide Tordon 10K has been selected to be used. It will be applied on individual small trees by sprinkling 1/2 the amount prescribed on the label around the base of the tree within the live root area of the tree. (See Page 3 of the attached Federal and State registrations, Tordon 10K Pellets Herbicide for an illustration.) Due to the nontoxicity of the herbicide to other organisms, it is anticipated that there will be very little to no adverse impacts generated by this proposal.
During the 1950's and 1960's extensive projects were undertaken on the Beaver Creek Ranger District, in which large areas of pinyon-juniper overstory were chained or pushed in order to convert these areas into open grassland types. Most of these projects were undertaken on the deeper soil types and involved areas which were formerly grasslands, but had been invaded by the woodland species due to fire being taken out of the ecology of the area. The conversion to a grassland was successful in most areas, and the introduced and native grass species are producing from 400-1200 pounds per acre, where 0-125 pounds per acre have been normal. Approximately 58,000 acres have been successfully type converted on the Beaver Creek Ranger District.
Presently the treated areas are the critical and primary rangelands on which the allotment management of most of the District's grazing allotments is based. These primary rangeland areas are being reinvaded once again by juniper trees. This is a very gradual occurrence, but the young trees are beginning to have an effect on the understory vegetation. The future competition between the junipers and the understory species for plant available moisture and sunlight is the reason that these small trees should be treated before any more of the current base forage is lost.
The treatment of these reinvading junipers may be accomplished by. several different methods as shown in the alternatives. Each of these alternatives has several positive and negative aspects (Issues and Concerns) that were felt to be of importance by the ID Team.
These issues and concerns are as follows:
These issues and concerns are dealt with further in this assessment.
The alternatives which the ID Team felt were logical are grubbing with machinery, broadcast burning, and chemical treatment with a selective herbicide. The alternative of no treatment is also considered as required. The alternatives of hand cutting or grubbing, and single tree burning were discussed but were not considered to be logical methods of treating large areas as required in this project. Past experience has shown that these methods are very slow and costly.
The four alternatives that are considered are as follows.
This alternative is to do no treatment and to allow reinvasion of juniper to continue as now is occurring.
This method can be accomplished with either tracked or wheel type machinery. Either type of machine would be fitted with a grubbing knife which sits on the front of the machine, and is lowered while the machine is moving forward. This causes the knife to dig in under the ground surface and either uproots or cuts the tree off. A bulldozer blade would not be effective in killing these small trees since they are small and very flexible and would just bend over when pushed with a blade. A truck type machine is slower and tears up more vegetation, but it is capable of working in rougher terrain and in rocky areas. The wheel type machine moves faster and doesn't tear up as much vegetation, but is limited to flatter terrain without much rock.
This method of eradicating the small juniper trees depends on having sufficient fuels present to carry fire plus sufficient fuels to burn hot enough to either ignite the trees or at least kill the cambium layer of the tree at ground level. Most areas that are proposed to be treated do have continuous fuels and could be burned from one control line to the next.
There is a lack of information as to how large of blocks, what time of year should you burn, and what result could be expected, when considering this alternative. A definite plan for burning cannot be formulated until some trial areas are treated first.
The method proposed for this project is to hand apply the herbicide Tordon 10K- at 1/2 the label rate to individual trees. The trees in the proposed treatment areas are not thick enough to warrant aerial or broadcast applications of herbicide. The herbicide Tordon 10K was selected by the use of trial plots. Three small sample plots, in which Tordon and Teburthiron were tested, were established and monitored. It was found that the Tordon was the most effective killer of juniper with the least amount of kill on the grass and forb species. Under this alternative the Forest Service will supply the Tordon 10K plus all the training and management to the permittees who are involved with the projects. The permittees will apply the herbicide according to the specifications and guidelines set forth in the labeling for Tordon 10K and by the Forest Service. By allowing the permittees to apply the herbicide, there will be a large savings in labor cost since alot of the application will be done while doing other ranch work.
Four evaluation criteria have been formulated from the Issues and Concerns that the ID Team felt were important to this project. These criteria are used to evaluate each alternative. The evaluation criteria are as follows:
The evaluation of the alternatives as they are related to the evaluation criteria is shown in the following evaluation matrix.
Control of the invasion trees with the selective herbicide Tordon 10K should have little or no adverse impacts on the environment.
The herbicide is selective to broad leaf and woody stemmed vegetation and must be applied directly over the live root influence area of the individual plant. The chemical then leaches and percolates to the root system where the plant picks it up. Due to the flatness of the terrain and present grass cover, the possibility of the chemical going anywhere but down is remote to nonexistent.
The active chemical in the herbicide Tordon 10K is Picloram, or 4-amino-3, 5, 6 - trichloropicolinic acid. The following excerpt from a paper entitled "Use of Tordon Products on Range and Pasture" by L. E. Warren, gives a rundown of the effects of Tordon on most organisms likely to be encountered in this proposal.
Biological Activity
Toxicity of Picloram to all animal life is very low (10). Rabbits, white rats, and other small and large animals and fowl will tolerate up to several thousand milligrams of compound per kilogram of body weight (mg/kg) in single doses. Continuous feeding of rather high levels for up to 2 years has not produced any adverse effects. All acquatic animal life also is very tolerant of Picloram (11). Essentially all the chemical passes through these organisms unchanged. No accumulation in animal tissues nor in food chains has been found from continuous feeding (12).
Picloram at recommended use rates does not affect micro-organisms in the soil (13). In fact, these micro-organisms are responsible for the decomposition of Picloram in soil; the decomposition is incidental in their normal metabolism; and no groups of organisms have been found to exist and build up on Picloram, such as occurs with Dalapon or 2, 4-D. The rate at which Picloram disappears from soil is related to the conditions that favor micro-organism activity. These conditions are adequate moisture, favorable temperatures, pH and salts, and at least a few tenths percent organic matter. The rates of loss vary greatly; in some areas where the soil is dry and/or cold for much of the year, 1/2 lb. per acre of Picloram can last for several years in amounts that will injure potatoes or beans (14). In the Southern Plains or Southeast, 3 lbs./ acre of Picloram was lost in 18 to 24 months (15).
Picloram is absorbed by both leaves and roots of plants in active growth, and translocated readily to all parts of the plants (16). Larger amounts accumulate in the growing points than in other parts. There is usually some slight exudation of Picloram from roots of most plants. Picloram can be stored in tubers and seeds in amounts that can affect growth of the new plants (14).
Response of rapidly growing susceptible plants to foliage sprays of Picloram products is visible in a few minutes to hours after treatment. Most broadleaf plants including hardwoods and conifers become twisted and distorted. Grass plants however are much more tolerant, although some grasses are affected less than others. Small grains will tolerate over 1/2 lb. per acre of Picloram in the soil as a preplant application, but over 1/2 oz. per acre typically on young grain with a few leaves can cause serious malformation and yield reduction (17). Most range and pasture grasses are quite tolerant, and will be rejuvenated by release from competition of the broadleaf weeds or shrubs (18).
All the drainage in the project area is to the southwest towards the Verde River. No real possibility exists for any downstream impact by application of the chemicals, since all the treatment areas are a considerable distance from major drainages and the Verde River.
Effects on vegetation other than the targeted species will be limited to other noxious plants. Thistle, rabbitbrush, and some forbs will be affected if the herbicide moves any, but there are no crops or desirable plants in the vicinity which could be affected.
Due to the very limited toxicity to anything other than the targeted species and direct method of application employed, very little adverse impact is anticipated from this proposal.
Parties with primary interest in this proposal are the grazing permittees, the Arizona Game and Fish Department, the sportsmen and hunters who visit the area, the local fuelwood cutters, and local environmental groups. These parties are being contacted for comments, through local clubs, organizations, and representatives.
The following individuals made up the Interdisciplinary Team, which discussed the proposed action and formulated the critical Issues and Concerns, and the alternatives.
Greg Goodwin, Wildlife Biologist
D. M. Howard, District Ranger
Ralph Pope, Range Conservationist
Bill Stafford, Recreation and Lands Staff
Mike Reamer, Fire Management Officer
Last Revised: 15 August 2001