Cone Fire Tests Fuel Reduction Treatment Effectiveness
CONE FIRE TESTS FUEL REDUCTION TREATMENT EFFECTIVENESS
Blacks Mt Experimental Forest and the Cone Fire, September 26, 2002
By Gary Nakamura, UC Cooperative Extension (Many photos courtesy of USFS PWS Research Station. Ecological Research Project, Redding, CA.)
The September 26, 2002, Cone Fire tested the effectiveness of a variety of fuel reduction treatments under severe fire behavior conditions of wind (10 mph), low humidity, and low fuel moisture. In 1996, an Ecological Research Study was established at Blacks Mt Experimental Forest using timber harvest, biomass harvest and prescribed fire to create different stand structures and fuel conditions. Eastside pine type forest with 2 to 3 age classes (200 year, 100 year, and <100 year, Photo 1) ponderosa and Jeffrey pine, incense cedar, and white fir, was thinned to 1) maintain high structural diversity while reducing ladder fuels (Photo 2) and 2) create low structural diversity (uniform stand structure) by harvesting all large, overstory trees, snags and thinning the ladder fuels, creating uniformly sized and spaced trees of the 100 year old age class (Photo 3). Large, 250 - 300 acre, treatment units were thinned to these two structures and prescribed fire was applied to half of each unit, further reducing logging slash, surface fuels, and fire hazard. Blacks Mt thus had the following stand and fuel conditions when the Cone Fire occurred September 26, 2002:
Untreated stands with multiple canopy layers, dense clumps
High diversity structure, with prescribed fire
High diversity structure, without prescribed fire
Low diversity structure, with prescribed fire
Low diversity structure, without prescribed fire
The Cone Fire burned from the NW and into Units 46, 43, and 41(Photo 4). The fire was driven by low speed winds from the NW, 10 mph, but the humidity was very low, in the teens and single digits, even at night, so fire conditions were considered severe. Fuel moisture was also very low with 3" + material at 8% moisture (critical levels are 12% or less).
Photo 5 is an oblique aerial photo showing fire behavior in Unit 46, a low diversity unit. On the left side, thinned without prescribed fire, the Cone Fire burned into the unit and killed trees (Photo 6); on the right side, thinned with prescribed fire, the Cone Fire was unable to burn (Photo 6); further to the right and above Unit 46, an untreated stand burned severely (Photo 7). Note in Photo 6 that brush had regenerated in the 2 years following the 2000 prescribed burn, but that brush and other surface fuels were not extensive or continuous enough to carry the wildfire.
Photo 8 shows the fire behavior at the interface between untreated forest (left, Photo 9) and Unit 41, high diversity with prescribed fire (right, Photo 10). The Cone Fire dropped from the crowns (flame lengths 1.5 times tree height or about 100 feet) to the ground when it entered Unit 41, but the radiant heat from the adjacent crown fire was sufficient to scorch and likely kill trees a few hundred feet into Unit 41. However, the wildfire did extinguish itself in Unit 41 (Photo 10).
Photo 11 is in the center of the untreated forest, the most severely burned area. No trees are alive and few have any needles remaining, the forest floor is completely consumed.
Conclusions - The Cone Fire tested the fuels treatments applied at Blacks Mt Experimental Forest under severe fire behavior conditions of wind, low humidity, and low fuel moisture. Units which received both thinning of ladder fuels (biomass harvest) and a follow up prescribed fire to further reduce surface fuels had the wildfire drop to the ground where they extinguished or could be safely suppressed, while units which were just thinned of ladder fuels had sufficient surface fuels to severely scorch trees. Untreated forest burned the most severely, with total tree kill, forest floor consumption, and canopy consumption.
It remains to be seen next year whether scorched trees will succumb to direct fire effects or insects and disease, or survive.
Click Black Mtn. Report PDF to download Adobe Acrobat file.
Blacks Mt Experimental Forest and the Cone Fire, September 26, 2002
By Gary Nakamura, UC Cooperative Extension (Many photos courtesy of USFS PWS Research Station. Ecological Research Project, Redding, CA.)
The September 26, 2002, Cone Fire tested the effectiveness of a variety of fuel reduction treatments under severe fire behavior conditions of wind (10 mph), low humidity, and low fuel moisture. In 1996, an Ecological Research Study was established at Blacks Mt Experimental Forest using timber harvest, biomass harvest and prescribed fire to create different stand structures and fuel conditions. Eastside pine type forest with 2 to 3 age classes (200 year, 100 year, and <100 year, Photo 1) ponderosa and Jeffrey pine, incense cedar, and white fir, was thinned to 1) maintain high structural diversity while reducing ladder fuels (Photo 2) and 2) create low structural diversity (uniform stand structure) by harvesting all large, overstory trees, snags and thinning the ladder fuels, creating uniformly sized and spaced trees of the 100 year old age class (Photo 3). Large, 250 - 300 acre, treatment units were thinned to these two structures and prescribed fire was applied to half of each unit, further reducing logging slash, surface fuels, and fire hazard. Blacks Mt thus had the following stand and fuel conditions when the Cone Fire occurred September 26, 2002:
Untreated stands with multiple canopy layers, dense clumps
High diversity structure, with prescribed fire
High diversity structure, without prescribed fire
Low diversity structure, with prescribed fire
Low diversity structure, without prescribed fire
The Cone Fire burned from the NW and into Units 46, 43, and 41(Photo 4). The fire was driven by low speed winds from the NW, 10 mph, but the humidity was very low, in the teens and single digits, even at night, so fire conditions were considered severe. Fuel moisture was also very low with 3" + material at 8% moisture (critical levels are 12% or less).
Photo 5 is an oblique aerial photo showing fire behavior in Unit 46, a low diversity unit. On the left side, thinned without prescribed fire, the Cone Fire burned into the unit and killed trees (Photo 6); on the right side, thinned with prescribed fire, the Cone Fire was unable to burn (Photo 6); further to the right and above Unit 46, an untreated stand burned severely (Photo 7). Note in Photo 6 that brush had regenerated in the 2 years following the 2000 prescribed burn, but that brush and other surface fuels were not extensive or continuous enough to carry the wildfire.
Photo 8 shows the fire behavior at the interface between untreated forest (left, Photo 9) and Unit 41, high diversity with prescribed fire (right, Photo 10). The Cone Fire dropped from the crowns (flame lengths 1.5 times tree height or about 100 feet) to the ground when it entered Unit 41, but the radiant heat from the adjacent crown fire was sufficient to scorch and likely kill trees a few hundred feet into Unit 41. However, the wildfire did extinguish itself in Unit 41 (Photo 10).
Photo 11 is in the center of the untreated forest, the most severely burned area. No trees are alive and few have any needles remaining, the forest floor is completely consumed.
Conclusions - The Cone Fire tested the fuels treatments applied at Blacks Mt Experimental Forest under severe fire behavior conditions of wind, low humidity, and low fuel moisture. Units which received both thinning of ladder fuels (biomass harvest) and a follow up prescribed fire to further reduce surface fuels had the wildfire drop to the ground where they extinguished or could be safely suppressed, while units which were just thinned of ladder fuels had sufficient surface fuels to severely scorch trees. Untreated forest burned the most severely, with total tree kill, forest floor consumption, and canopy consumption.
It remains to be seen next year whether scorched trees will succumb to direct fire effects or insects and disease, or survive.
Click Black Mtn. Report PDF to download Adobe Acrobat file.