The Kern River Ranger District, Sequoia National Forest is proposing the control of tamarisk, more commonly known as salt cedar, at Isabella Lake. Treatment of invasive tamarisk would use a combination of herbicides, hand-grubbing, and mechanical removal of plants. This variety of tamarisk, Tamarix ramosissima, is a highly invasive non-native species that is harmful to native ecosystems.
Tamarisk has the potential to outcompete and replace native plant species, salinize soils, monopolize limited sources of moisture, and increase the frequency, intensity and effect of fires and floods. These effects can degrade wildlife habitat, establish dense monocultures that affect recreation values and block water flow in natural channels and irrigation ditches. Tamarisk has taken over large sections of riparian ecosystems in the western United States that were once home to native cottonwoods and willows.
The District completed hand treatments to eradicate small, isolated plants of tamarisk, tree of heaven and Russian olive at Isabella Lake in the mid-1990s; but new populations of tamarisk were observed in the winter of 2013 at Isabella Lake, and they have rapidly expanded. The current tamarisk population on National Forest System lands at Isabella Lake spreads across approximately 1,500 acres, and consists of a thousand or more plants which range from small seedlings to well-established plants (5 to 6 feet tall and over 3 inches in diameter at their base).
Tamarisk can spread both vegetatively (by roots or submerged stems) and by seeds. Each flower can produce thousands of tiny seeds that are dispersed by wind and water, allowing it to spread rapidly. It is able to withstand extended periods of inundation and drought, and it has long tap roots that allow it to out-compete other plants for natural water resources. Tamarisk is also able to limit competition from other plants by taking up salt from deep ground water, and depositing it in the surface soil.
Hand-grubbing and cutting of above-ground tamarisk stems was accomplished in May and June of 2014 within several hundred acres of the lake bed. This treatment alone has proven to be an ineffective long-term solution for the control of this invasive species since it readily sprouts from cut roots; and new growth from salt cedars cut last year is already evident in the lake bottom. Due to the extent of the infestation and the size of the plants, herbicides are the most practical and effective means of control.
The Desert – Mountain Resource Conservation District, Audubon California, and other partners have been successfully treating and removing invasive plants on private lands in the Kern Valley and Walker Basin areas for several years under the Kern River Valley and Walker Basin Agricultural Lands Improvement grant from the Sierra Nevada Conservancy. These treatments used the recommended herbicide prescription of Pathfinder and a combination of Hasten Oil, Stalker and Garlon 4. These are non-restricted herbicides that are sprayed on the bark at the base of the plants.
The Forest Service proposes to follow this treatment since it has been shown to be effective while minimizing herbicide use on non-target plants. Application of the herbicides will be conducted by hand directly on the target plants and not by broadcast or aerial spraying. Herbicides will not be used in areas where there is open water. Tamarisk that are in standing water at the time of treatment will be hand-grubbed or pulled to reduce or eliminate seeding until the plant can be treated.
Currently the designated Critical Habitat for Southwest willow flycatcher and proposed Critical Habitat for yellow-billed cuckoo at Isabella Lake are not affected by tamarisk and would not be affected by the proposed treatment.
The District plans to prepare an environmental assessment to document analysis of the effects of this project. We appreciate any information or substantive comments that are within the scope of the project and the decision to be made. Please send your written comments to Steve Anderson, Kern River Ranger District, PO Box 9 (105 Whitney Road), Kernville, CA 93238, by e-mail email@example.com with “Isabella Tamarisk Control Project” in the subject line by April 3, 2015. The complete scoping letter can be found online athttp://www.fs.usda.gov/project/?project=44853.