Presribed Burning and Wildfire
(Fire as a Tool in Saltcedar Management)

Bruce R. West

USDI Bureau of Land Management
150 Coolwater Lane
Barstow, California 92311-3221
Phone: 619-255-8731
FAX: 619-255-8799
E-mail: bwest@ca2224.bara.ca.blm.gov

The Barstow Resource Area has battled saltcedar (Tamerix ramosissima) in Afton Canyon, located on the Mojave River 38 miles northwest of Barstow, California, since 1992. Many saltcedar control and riparian restoration elements, or tools, have been utilized in this struggle to return the canyon to a functioning riparian community. Fire has proved to be an effective and important tool in this long range riparian restoration project.

Prior to making a commitment on a saltcedar control/riparian restoration project, the site should be evaluated and your goals assessed for reasonableness. Questions to ask would be:

 

* Is the saltcedar problem manageable with available current resources. The resources to consider are personnel, funding, equipment and material.

* What natural resource improvements are expected? Is open water your goal or are there other priorities such as the restoration of the riparian habitat more important. Oftentimes several related resource improvements are anticipated.

* What saltcedar control and riparian restoration methods would work best in your situation?

A management goal of controlling saltcedar to manageable levels and improving the functioning ecological condition of the riparian habitat in Afton Canyon was first identified in the Afton Canyon Area of Critical Concern (ACEC) Management Plan. The management actions developed to reach this management goal primarily include the removal of saltcedar and revegetation of the treatment area with native plants. The principal rationale considered in the Afton Canyon Restoration Project, as stated by the ACEC plan, was to improve wildlife habitat within the canyon bottom.

In preparation for the initial prescribed burn, photo monitoring plots were established within the dense, mature saltcedar of the proposed burn area. The photo plot locations were extremely difficult to access because of the thick saltcedar. The plots were within monoculture stands of saltcedar that had developed heavy accumulations of branches, woody material and thick duff. The duff was deposited on the branches as well as on the soil surface. Other actions undertaken prior to the prescribed burn were the construction of fire breaks around native trees and the building of fire fuel jackpots. These jackpots consisted of stacked cut, and other, woody materials utilized as initial ignition points to provide a high intensity energy source to pre-heat nearby material, help get the fire going and create a fire wind.

The initial date for the prescribed management burn in Afton Canyon was November, 1991. This period was chosen because it was assumed that the saltcedar would be dormant, fuel moistures would be fairly low and temperatures/humidity would be moderate. As with many well laid plans, the saltcedar would not ignite. The winter rains began shortly thereafter, and the burn was on indefinite hold. On the last day of July, 1992 we tried again. The jackpots were lit and soon the saltcedar was an inferno! The high temperatures, light winds and low humidity provided ideal conditions for the prescribed burn. The flame lengths reached approximately 100 feet, threatening the native trees located within the fire breaks.

The fire was very effective. All that remained standing were larger blackened saltcedar stems and trunks. The smaller branches, duff, leaves and decadent limbs were all consumed. The fire visibly opened the burn area allowing the soil to be clearly seen between the blackened standing material. The fire encompassed approximately 80 percent of the proposed burn area. The areas where the fire didn't carry were usually in younger age stands and/or near the perimeter of the wet "green strip" where fewer combustible materials were available and moisture levels were higher.

The intensity of the fire was very high, killing the saltcedar outright in some areas and scorching many of the native trees that we had tried to protect. It was found that, to protect existing native trees, firebreaks must exceed 100 feet. Some of the above ground portions of the native trees survived and most that didn't resprouted basally. The resprouted willows are currently between ten and fifteen feet in height and growing. The results demonstrate that the initial contribution gained from the use of fire on saltcedar is that it opens the very dense stands to allow access for the spraying of resprouts.

The burned saltcedar began to basally resprout within a month following the burn. Different age classes and sizes of the burned saltcedar had different degrees of accessibility. The more tree like stands with larger, well spaced standing material were easier to access for herbicide application than the more closely spaced and younger age "thickets." Application of herbicide to the resprouts began approximately one month following the burn.

The herbicide was applied using backpack and other hand carried pump sprayers. The saltcedar resprouted very quickly and grew very rapidly, six feet in a period of a few months, so it was imperative that the resprouts were promptly treated with herbicide. We learned that the larger the resprouts, the more time and herbicide it takes to spray each resprout. We recommend that saltcedar resprouts should be sprayed immediately upon their appearance, though this often requires several spray treatment sweeps. For this initial burn, it is estimated that our initial treatment of saltcedar resprouts was 80 percent successful.

The herbicide used for initial resprout treatment was Pathfinder, a pre-mixed Dow-Elanco product with trichlorpyr as the active ingredient and petroleum distillate as the carrier. We have since switched to the more benign Pathfinder II with its vegetable oil-based carrier. Along with other human comfort problems, the petroleum based carrier in the original Pathfinder caused the rubber gaskets and hoses in the compression pump sprayers to weaken and fail. In the future, we are also considering using Rodeo, a Monsanto product, for saltcedar control that is specifically labelled for water use.

Mother Nature sometimes changes the plans of mere mortals. In the winter months following the burn and herbicide treatment, the Mojave River had one of its more substantial flood flows. This changed the landscape of the canyon bottom. In some areas the high water scoured out much of the small, wispy saltcedar, while in other areas there was soil deposition and the burying of uprooted saltcedar. Our burn treatment area was located on a terrace and was unaffected except for some soil deposition and small channelized flows. The impacts to other areas of our restoration area were both beneficial and detrimental. The fresh soil deposition created ideal pole planting sites but also covered piles of saltcedar which would later come to life. This flood also washed upstream portions of untreated saltcedar into downstream treated areas.

In the spring of 1994, following the flood event and a year of herbicide treatment, we began our restoration effort. From January through March we harvested and planted several hundred Fremont cottonwood (Populus fremontii) and Goodings willow (Salix nigra var. goodingii) poles in and around the burn area. BLM staff, prison inmates and high school volunteers all helped in this endeavor.

The poles were placed in augured holes approximately three to five feet deep; most poles reached the water table. Our success from these first pole plantings was not very good with only ten percent survival. We later found that plantings were more successful near the edges of the burn, in areas where there was more deposition from the flood and where saltcedar was cleared using the cut stump method, rather than a burning technique.

Native plants propagated naturally following the burn. Chinese pusley (Heliotropium convolvulaceum var. californicum), kochia (Kochia americana) and other site stabilizing plants quickly established. Native trees that were burned in the fire also began to resprout. Mesquite trees vigorously resprouted only to be attacked by rabbits and other small mammals. The willows, which presently are approaching 20 feet in height, also vigorously resprouted. Following the burn and subsequent flood, cattails, sedges and other wetland plants popped up everywhere within the wetland and marsh areas. Later, arrowweed (Pluchea sericea) and quailbush (Atriplex lentiformis) became established.

The burn also opened up the canyon to wildlife. Says phoebe (Sayornis saya) are now observed regularly enjoying the increased visibility, openness, snag perches and grass/forb meadows. Bobcats (Lynx rufus), bighorn sheep (Ovis canadensis), coyotes (Canis latrans) and many other species of birds and wildlife now enjoy the canyon and the increased open water.

Cottonwood trees planted in 1994, within areas of heavy soil deposition and protected from the wind and blowing sand, have thrived. Whereas, survival of cottonwood/willow poles in wind exposed areas has been relatively low. Trees in sheltered locations have reached heights greater than 15 feet. As stated above, this is the exception. Although the survival rate for our cottonwood/willow pole plantings have been lower than anticipated, this disappointment is not deterring current, or future, restoration efforts. We are continuing our saltcedar control and riparian restoration efforts in Afton Canyon. Our latest pole planting effort, during winter and spring of 1996, totaled approximately 2,500 trees. To date, well over 5,000 native cottonwood and willow poles have been placed in the Afton Canyon project area, with survival rates gradually increasing.

The construction of riparian enclosure fence is another tool that has been utilized in the Afton Canyon restoration effort. The present project area is in an active grazing allotment. In the past it has also experienced heavy off-road vehicle use. The constant soil disturbance from these activities created ideal seed beds for salt cedar germination. Physical damage to native and planted cottonwood/willow poles also was occurring. Additionally, native plantings were being grazed by cattle and crushed by vehicles. In the spring of 1995 a riparian enclosure fence was constructed to control these activities within the treatment area.

The vision of a sprouting saltcedar next to a young cottonwood pole leafing out symbolizes the struggle taking place between the native plant community and the invading exotic plants. We in the Barstow Resource Area believe that some selected degraded riparian habitats can be returned to functioning condition by controlling the saltcedar and through the stated revegetation/restoration efforts. Native plant communities need help and we intend to keep working in Afton Canyon until our saltcedar nemesis is under control.

When the Afton Canyon Restoration project began many people commented that we were crazy even to attempt a saltcedar control on such a large scale; "It can't be done", "You're wasting your time," they said. Well, the war certainly hasn't been won, but we intend to keep fighting.

In conclusion, it is hoped that this report provides a little more insight into the Afton Canyon Restoration Project and how fire is being used as one tool in saltcedar control and riparian restoration. There are still many questions on the use of fire and follow-up restoration, as well as, revegetation of burned areas. Primary among the questions are:

 

* What do you do about boron and salt accumulation in burned saltcedar stands?

*Are there easier ways to treat saltcedar resprouts?

There is a need for more research into fire behavior, fire history and the revegetation of saltcedar burns. Even with these questions, it appears that prompt herbicide treatment after the prescribed burning and/or wild fire in saltcedar is an excellent tool to consider in the treatment of mature, dense saltcedar stands.


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