Helena National Forest

Elkhorns Wildlife Management Unit

Prescribed Fire Monitoring Report

Elkhorns: Elkhorns and Fire: BLM Monitoring Report

South Elkhorns Vegetation Treatment Implementation
Prescribed Fire Evaluation Report
Bureau of Land Management
Butte Field Office

Prepared by: Jodie Canfield, Wildlife Biologist

Prescribed Fire Unit 4VV before and after treatment

Methods     Results    Discussion    Recommendations

The Forest Service, and Bureau of Land Management (BLM), in cooperation with Montana Department of Fish, Wildlife and Parks (MDFWP), undertook a landscape analysis of the southern portion of the Elkhorn Mountains , which was completed in 1996. The analysis area comprises approximately 80,000 acres of public lands managed by the Beaverhead-Deerlodge and Helena National Forests and the Butte Field Office, BLM. With BLM as the lead agency, a site-specific project analysis was completed in 1998. This analysis, documented in an Environmental Assessment (EA) examined the effects and explored different alternatives of managing vegetation and livestock in the southern Elkhorn Mountains. A decision was issued in January 1999. Due to appeals and litigation, the Forest Service has not been able to implement any portion of that decision; however, BLM has been actively implementing since spring 1999.

Vegetation in the southern Elkhorn Mountains has been influenced by many factors, but the landscape analysis indicated that many of the current vegetation conditions result from a combination of past timber harvest, fire suppression, and past livestock grazing.

In an area where studies showed a more frequent influence of natural fire prior to about 1930, the vegetation has been slowly changing to include more shrubs and trees in historic grasslands, aspen stands, and meadows. Dry, lower elevation forests, once thinned by frequent, low intensity fires, are now mostly very dense and shaded. There are no grasses or wildflowers under these trees, and in some cases, insects and disease are more common due to the competitive stress of too many trees for the limited amount of nutrients and water.

In some places, past and current concentrations of livestock have contributed to poor soil and plant conditions in both riparian and upland areas. Past timber harvest practices, both by miners for cordwood/mining timbers, and by the Forest Service have affected the composition and structure of forested areas. Many were thinned taking the larger trees and leaving the smaller trees.

The project proposed by the agencies was intended to initiate vegetation treatments that would move toward the desired conditions for structure, function and composition. Proposed treatments included prescribed burning of grassland/shrublands, and prescribed burning combined with either non-commercial or commercial thinning (timber harvest) in forested areas. Treatments on core elk winter range and to enhance key forage shrub species were emphasized.

Grassland/shrubland prescriptions included the use of prescribed fire to reduce conifer colonization and increase or restore site productivity. Treatment prescriptions included burning in a "mosaic" pattern where 30-70% of the burn unit would be actually burned, depending on objectives for wildlife, soils, and/or vegetation.

Non-commercial prescriptions included treating vegetation both mechanically and with prescribed underburning to reduce fuel loadings and reduce conifer tree densities. This type of treatment was intended to convert dense multi-aged forests to more open stands of older, larger trees by removing smaller trees with chainsaws.

As of the spring of 2002, most of the BLM units in this project have been implemented. Monitoring of the treatment results has been on-going. This report summarizes those monitoring efforts and makes recommendations to improve the effectiveness and efficiency of similar future projects.

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Prescribed burn units were evaluated using the following:

1. Objectives from the Decision Notice
2. Burn Plan data
3. Monitoring field reviews
4. Pre and post photo point pictures
5. Pre and post vegetation mapping
6. Interdisciplinary field discussions

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The Decision Notice for the BLM portion of the South Elkhorns included prescribed burning or non-commercial treatments on about 6,400 acres. Units were burned in the spring between March 1999 and May 2002. As of June 2002, 15 units totaling about 6,100 acres had been treated with prescribed fire and 150 acres with mechanical (saw work) only. The remaining treatment units (3) are scheduled for spring, 2003.

Within the burn units themselves, about 2,600 acres were affected by varying fire intensities. Therefore, on average, 40% of the acres included in the units were affected by fire. Full consumption of the vegetation occurred on 1,050 (17%) of the total acres included in the burn units. Table 1 contains information specific to each unit on the objectives and results.

The units were burned within the full range of the prescribed conditions for temperature, humidity and wind speed, using both hand and aerial ignition techniques.

Objectives, based on the Environmental Assessment and Decision Notice, for the burn units in general were not achieved.

Although weeds increased in several of the burn units after treatment, post-weed treatment has been generally effective in eradicating this increase. Wooly mullein is often a dominant plant species in burn units where fire intensity was high.

Grazing management relative to the burn units was variable, but generally the units were rested one season before and one growing season after treatment.

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The southern portion of the Elkhorn Mountains had frequent fire prior to European interference in the natural (including native American) disturbance regime (Lehman 1995). Based on a Master’s thesis by Lehman, the average fire interval was less than 15 years. About 90% of the fire scars detected in her study were dated prior to 1910. In Therefore, 4 fire cycles have been “missed” due to a variety of factors including fire suppression and livestock grazing. This has resulted in very dense conifer cover in places that have the potential to support grass and/or shrubs. This is evidenced in the south Elkhorns in some areas as dead sagebrush among dense Douglas fir, limber pine, and juniper. It is also evidenced as bare soil having sparse grass cover in between dense conifers. There is much evidence of active soil erosion in the south Elkhorns on BLM lands.

There is no question that fire is an integral part of this ecosystem. The question is how can managers re-introduce fire in the face of concurrent changes in human values, human uses, and the occurrence and concern about noxious weeds.

People value scenery. As such, large portions of the landscape blackened by fire are often not acceptable (although inevitable in a wildfire situation). People value recreational hunting and therefore conifer cover, which provides security for big game animals.

Winter range for game animals has been dramatically reduced by cultivation and subdivision. This makes the winter range on public land that much more valuable. Mule deer and antelope in the south Elkhorns often use sagebrush for winter forage. Sagebrush is easily killed by fire and therefore, prescribed burning is often not acceptable to game managers on these important winter ranges.

Livestock grazing is an important land use in this portion of rural Montana. Livestock management influences where fire can be used and how successful fire will be in reducing fuel loadings.

The South Elkhorns Range and Vegetation Project was a first attempt to try and balance the need for fire while still having sensitivity to these other issues. The interdisciplinary team (ID team) included representatives from Fish, Wildlife and Parks as well as biologists from the Forest Service and BLM. The biologists designed the selected alternative and designed the mitigation measures that were integrated into the burn plans.

By design then, implementation of the South Elkhorns decision was constrained by stringent sideboards. In addition, the ID team, in order to predict effects, estimated the change in vegetation that would occur in each unit after burning. They did this using a technique that involved converting categories of vegetation into other categories. These categories, high tree, mid-tree, low-tree, and grass/shrub were adequate in describing the existing vegetation conditions. However, the ID team assumed that conversion would occur incrementally (i.e. from high to mid, mid to low, and low to grass). This was not the case and was the main reason why these predications were inaccurate.

The main objective of burning was to remove encroaching conifers from grasslands and to thin dense forests. These were not met for a variety of reasons. In terms of the first objective, conditions in the south Elkhorns have been so dramatically altered by plant succession that one application of fire was not enough to really set back the colonization of conifers into historic grasslands. Also, because of inherently shallow soils and because of soil erosion, fine fuels, needed to carry fire into the conifer “walls” were lacking in many of the burn units. Forests in the south Elkhorns are so dense that fire either did nothing (i.e. stopped when it reached the timber) or stand-replaced patches of dense forest. This explains why the ID team’s predications of incremental change were not valid.

During a field review with the ID team, another reason was proposed as to why objectives were difficult to attain. This was that many of the units were not “logical” for the application of fire. They included too much variation in vegetation, topography, and fuel loadings. They were not based on allotment boundaries either. Therefore, it was difficult to manage resting livestock on several allotments in one year, and sometimes units were grazed prior to burning.

Burning windows were generally adequate during the years when the project was implemented. The project was implemented during a sustained drought. This meant that fuels were generally drier than “normal” spring conditions and resulted in more “natural” but less controllable conditions. Due in part to the drought, prescriptions were designed conservatively. Many burns ignited at the low end of the prescribed ranges of temperature, humidity and wind speed did not meet objectives. Those burn units ignited at the mid-high end of the prescriptions generally achieved decent results. Many of the units were too big for practical hand ignition. There was often pressure to burn, even under low-end conditions, because of grazing schedules, and the financial burden of lining up aircraft and supporting ground personnel. Where soils and grass cover were good, burn results were also good.

Weed treatments are critical. Where weeds were treated in the burn units of the south Elkhorns, burning effects were generally beneficial. Although mullein was a dominant plant species in some areas, it is not considered “noxious” and is replaced by other later successional species over time.

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The monitoring of the prescribed burn units was fruitful in that it brought forth the successes and failures of the project. Based on this assessment, and the ID discussion in the field, the following are recommendations designed to produce better results for similar projects in the south Elkhorns.

1. Use the RMP revision as a way to set the stage for another large project in the south Elkhorns. Focus units on areas with good soils.
2. Unit design should be accomplished through team field review with both fire and resource specialists input. The unit boundaries should be based a single focus (i.e. not forest and grassland) and use natural fuel breaks. The units should be coordinated with administrative boundaries such as grazing allotments to help facilitate “rest” before and after treatment. Units should also have a “contingency” boundary based on some kind of risk assessment (probability of escape).
3. Units should be field reviewed to assess realistic objectives for treatment results and to assess the need for weed pre-treatment and mechanical preparatory work. Some units (with advanced succession or poor soils) may need to be treated up to 3 times during a 5 year period to achieve desired conditions and this should be given consideration in the planning document.
4. Units should be black-lined. This gives greater flexibility in the burn window and the fire behavior in the black lining operation can give insight into the prescription needed for achieving the objectives in the burn unit itself.
5. Mechanical treatments are necessary to “thin” forest with burning. Spacing should be 16-32 feet and leave trees should be limbed up. Fuels left should be limbed and bucked and scattered.
6. With the amount of country needed to treat, burn units may be too large to safely hand-ignite. Helitorch capacity will increase the effectiveness and flexibility of burning in this geographic area.
7. To have effective prescribed burning in this area, managers will need to consider temperatures 60-70 F, humidity of less than 30% and sustained winds of 5-10 mph. Wind is important in the south Elkhorns to remove conifers.
8. Units should be reviewed for weed treatment the first year and then revisited 3-5 years later. Infestations should be located with a GPS unit to facilitate future treatments.

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USDA Forest Service - Helena National Forest
Last Modified: Monday, 25 June 2007 at 17:12:09 EDT