Recovery Plan for the Northern Spotted Owl - DRAFT

B. Management Effects on StandsManagement effects on fire in the Klamath subregion are complex. Historicalfire return intervals varied considerably, and the fire severity associated withthese historical events was also quite variable. Fire suppression has been apolicy since early in the 20th Century, and for the most part it has been asuccessful strategy. The effect of fire management can perhaps be broken intotwo periods: the 1900 to 1980 period, and the period 1980 to present and thefuture.In the beginning of the former period, large fires occurred in the subregion(179,000 acres in 1907; 152,000 acres in 1918 on the Siskiyou NationalForest; Atzet et al. 1988). The effect of fire management up into the 1980s wasto suppress all fires but those burning under the most severe conditions. Totalburn acreage declined, although the acres that did burn usually were scorchedmore heavily than in prehistoric fires. The average size of the "large fire" (ClassE+: more than 300 acres) between 1950 and 1980 in the Siskiyou and RogueRiver National Forests was 747 and 327 acres, respectively (Hardy 1983). Thisaverage has ballooned since then on the Siskiyou National Forest with the1987 fires (Helgerson 1988). In the Klamath National Forest in northernCalifornia, a U-shaped distribution of average total area burned exists from1950 to 1988 (Perkins unpublished data). The 1950-60 annual average was11,605 acres, which dipped to 4,862 acres in 1960-80; the large 1987 fires(more than 275,000 acres on the Klamath National Forest) increased theaverage for the decade 1980-88 to 31,140 acres.The success of the fire suppression policy allowed fuels to build in remainingprotected forests. The patchiness of variable fire severity was removed, andfuels became more continuous, both horizontally and vertically. Thick understoriesof conifers and/or hardwoods developed. Slash left after timber cuttingoften was treated by broadcast burning, and yarding of unmerchantablematerial (YUM yarding) also was done in some locations to reduce fuel hazardpotential (Hardy 1983).The recent period has been characterized by a trend toward larger fires. Amore continuous fuel complex over the landscape is at least partially responsible,fuels have increased within protected stands, and clear-cut stands haveexposed slash, not all of which has been fuel treated. In 1987, an extensivelightning storm set off more than 600 fires in southern Oregon, including 19which reached more than 1,000 acres in size (Helgerson 1988). Fire suppressionforces were overwhelmed, and some fires burned for months over rough,semiaccessible terrain. Fires burned at night, during cool days, on hot days,up and down slopes, essentially spreading over a wide variety of burningconditions. The 1987 fires were the third largest fire event on record in theSiskiyou National Forest, burning 190,000 acres in southern Oregon, morethan half were on the Siskiyou National Forest. About 775,000 acres innorthern California burned during the same time, mostly on national forestland (Atzet et al. 1988).A mosaic of fire severity resulted. Less than half of the area of most of thesouthern Oregon fires burned with high intensity, with the remainder burningat moderate and low intensity (Gross et al. 1989). In northern California onthe Hayfork District of the Shasta-Trinity National Forest, burned stands hadabout 5 percent of the area burned with crown fire consuming more than 50percent of the crown; with another 25 percent of the area more than 50 percentscorched: about 32 percent was 10 to 50 percent scorched; while the remaining38 percent was less than 10 percent crown scorched (Weatherspoon andSkinner unpublished manuscript). It is not possible to reconstruct what those458