USDA Forest Service Fire and Aviation Management Briefing Paper Date: July 22, 2015

Transcription

1 USDA Forest Service Fire and Aviation Management Briefing Paper Date: July 22, 2015 Topic: Fuel Treatment Effectiveness on the Corner Creek Fire, Oregon Key Points: 1) The presence of fuel treatments provided opportunities for firefighters to control the spread of the 2015 Corner Creek fire and contributed to more favorable natural resource outcomes. 2) Invasive species appear to be altering the landscape by creating flammable fuel conditions on previously barren sites. Background: The Corner Cr. fire started by lightning on June 29, 2015 on the Ochoco National Forest approximately 11 miles south of Dayville, OR. Because of the fire s growth potential and expected negative consequences should it reach surrounding private lands, communities, and sage grouse habitat, the management response was to extinguish the fire before it could impact those surrounding values. Initial efforts to control the fire were hampered by unseasonably hot and dry weather with daytime temperatures reaching 100 degrees Fahrenheit and relative humidity at or near single digit. Such extreme weather resulted in aggressive fire behavior that made control efforts more hazardous and often ineffective. In these conditions, the fire continued to surge past control efforts to the south for over a week forcing firefighters to concentrate efforts on holding the fire west of the South Fork of the John Day River. By July 5 th, the weather eased slightly allowing firefighters opportunities to finally control the fire s southern progression. As of this report, the fire is 90% contained and estimated at 29,407 acres mostly on USFS and BLM lands. Containment efforts on this fire were aided by utilizing previously treated areas where thinning and/or prescribed fire had occurred. Besides providing opportunities for firefighters to control the fire, the treatment areas also experienced less damage from the passing fire resulting in only minor impacts that are largely favorable in terms of reducing fuel accumulations and mimicking natural disturbance patterns. The Ochoco NF will be performing a more detailed assessment of the impact of fuel treatments on this fire. As a precursor to that assessment, the following are some initial observations captured from interviews with response personnel and observations of a limited number of sites where the Corner Creek fire encountered existing fuel treatments. Initial Observations: Fuel Treatments Contributed to Safer, More Effective Control of the Fire - Fuel treatments proved to be a considerable advantage in halting the southerly march of the Corner Creek Fire toward private property and sage grouse habitat. One firefighter interviewed commented that the more recently treated areas acted as barriers to fire spread and allowed firefighters opportunities to engage the fire directly while the older treatments did not slow the fires spread as much but did effectively lower the intensity of the fire as compared to surrounding untreated areas. In most cases treatments reduced the intensities to a level that firefighters were more comfortable and more successful in controlling the fire in those previously treated areas than they had been while trying to suppress the fire in untreated areas. 1 of 5

2 Fuel Treatments Contributed to Minimizing Damage and Improving Ecological Outcomes Eye-witness accounts reported several instances where the intensity of the fire was reduced when it encountered a previously treated area. In timbered areas, the fire mostly burned grass and litter without doing much damage to the overstory trees, a similar pattern to what would be expected in a natural fire regime for this area which would have experienced frequent low-intensity fires. The Combination of Thinning Followed by Prescribed Fire Appeared More Effective than Thinning Alone A few treatment areas had been thinned but the residual slash had not been treated with prescribed fire. Visual evidence suggests that fire behavior was reduced when the Corner Creek fire entered these thinned stands from surrounding untreated areas, however the residual slash did cause more heat damage to the remaining trees than was evident in similar stands where the slash had been reduced using prescribed fire after the thinning treatment. Effectiveness of Fuel Treatments Diminished by Recent Influx of Invasive Plants Local manager s report that scabby ridges with sparse, scattered vegetation have historically acted as barriers to fire spread. Most fuel treatments focused on adjacent timber stands, thus the combination of treated timber stands and barren ridges would normally be an effective means to limit large fire spread. Recently however, there has been an increase in what local managers identify as the invasive Ventenata (Ventenata dubia, a.k.a. North Africa grass) which has become well established in many of these previously barren sites. This has changed these open ridges from being fire resistant to where they are now quite receptive to fire. Firefighters witnessed rapid fire spread fueled by these dry grasses. This change in the landscape may have negated some of the advantage that the fuel treatments provided as the fire was now able to quickly run around the treated timber stands in the newly established grasses. Quotes from Jeff Priest, Type 3 Incident Commander and Division Supervisor on the Corner Cr. fire: Fuel treatments allowed for direct attack in some areas, and in other areas they allowed us to pick up spots easier. Places that were treated had better fire effects, mostly low intensity and just burning grass and dead stuff below the timber. They also helped our holding efforts while untreated areas caused us more control problems. The treated areas almost always reduced fire behavior, but where there was ventenata it didn t matter, the fire just ran through the ventenata and kept on going. 2 of 5

3 Figure Corner Creek fire perimeter in relation to fuel treatment areas as well as Core sage grouse habitat (shaded area lower left). Fire spread for this event was primarily north to south. 3 of 5

4 Photo 1. Corner Creek fire, July 2015 moved from the previously untreated area (left) into a prescribed fire that was conducted earlier in the year (right). Visual evidence suggests that fire intensity was significantly reduced as the fire entered the treated area allowing for direct control of the fire edge. Photos 2 & 3. Fire effects. Tree on the left had prescribed fire applied in April, 2015 while the tree on the right did not. The prescribed fire burned primarily in the pine needles that accumulate below the tree which is now evidenced by the green vegetation that now encircles the tree. When the July 2015 Corner Cr. fire approached it burned surrounding vegetation but did not impact the tree much at all. In contrast, the tree to the right was just outside the prescribed fire area (visible in the background) and when the Corner Cr. fire approached, it did burn directly below that tree where needles had accumulated causing enough scorch damage that this trees survival may be in question. 4 of 5

5 Photo 4. Example of typical scab area that is now filling in with Ventenata also known as North Africa grass. Normally there would be only scattered low sage, a few succulents such as wild onion, and considerable bare ground among the rocks, which in previous years would make these areas resistant to fire spread. Photo 5. An extreme example of Ventenata also known as North Africa grass colonizing a new site. This grass is becoming more prevalent on the Ochoco National Forest creating a new concern for fire and resource management. Contacts: Brenda Hallmark, Fuels Program Lead, Ochoco National Forest, Prineville BLM, and Crooked River Grassland, (541) ; or Frankie Romero, US Forest Service, Fire Use and Fuels Management Specialist, National Interagency Fire Center, (208) of 5