Resolution No. 4814 - Laserfiche WebLink

Home Browse Search

fight and thus harder to contain than are fires with better access for fire suppression crews and apparatus. in the 1930s, wildfires consumed an average of 40 to 50 million acres per year in the contiguous United States, according to US Forest Service estimates (US Forest Service, Managing the impact of Wildfires on Communities and the Environment, September 8, 2000). By the 1970s, the average acreage burned had been reduced to about 5 million acres per year. Over this time period, fire suppression efforts were dramatically increased and firefighting tactics and equipment became more sophisticated and effective. For the 11 Western states, the average acreage burned per year since 1970 remained relatively constant at about 3.5 million acres per year. However, because of this pattern of more effective suppression of wildland fires, the patterns and characteristics of wiidland fires are changing. Vegetation species that would have normally been minimized by frequent fires became more dominants Over time, many species have become susceptible to disease and insects, leading to an increase in dead and dying trees. The resulting accumulation of debris has created the types of fuels than promote intense, rapidly spreading fires, in many areas introduction of nonmative species has also added to the fuel load. Decades old patterns of ~ogging and fire suppression have also changed the characteristics of forests. Older forests were typically ~ess dense, with smaller numbers of larger, more fire-resistant trees. Newer forests are denser with larger numbers of smaller less fire- resistant trees, in combination these effects over the last several decades have resulted in many recent wildland fires that are hotter, faster, and larger than those experienced in the past. 9,1.3 Wildland/Urban interface Fires Wild,and/urban interface fires are fires where the fuel load consists of both vegetation and structures. In Oregon, as elsewhere in the United States, recent patterns of development have led to increasing numbers of homes being built in areas subject to wildland fires. Development in these areas may pose high levels of life safety risk for occupants as well as high levels of fire risk for homes and other structures. Urban or suburban areas may have a significant amount of landscaping and other vegetation. However, in such areas the fue~ load of flammable vegetation is not continuous, but rather is broken by paved areas, open space and areas of mowed, often irrigated, grassy areas with Iow fuel loads. In these areas, the vast preponderance of all significant fires are single structure fires. The combination of separations between buildings, various types of fire breaks, and generally Iow total vegetative fuel loads make the risk of fire spreading much lower than in wildland areas. Furthermore, most developed areas in urban and suburban areas have water systems with good capacities to provide water for fire suppression and organized fire departments who typically respond quickly to fires, with sufficient personnel and apparatus to control fires effectively. Thus, in such areas the risk of a single structure fire spreading to involve multiple structures is generally quite Iow. Areas subject to wildland/urban interface fires have very different fire hazard characteristics. The defining characteristic of the wildland/urban interface area is that structures are built in areas with essentially continuous (and often high) vegetative fuel Public Review Draft: August 6, 2004 9-8