adults and larvae, that are removed during 

 winter and early spring salvage operations 

 nnay still have green crowns. Once a tree has 

 died from bark beetle attack, it is no longer 

 suitable as habitat. 



Characteristics of stands that are highly 

 susceptible to attack by Douglas-fir bark 

 beetle form the basis for a Douglas-fir bark 

 beetle hazard-rating system that categorizes 

 stands as having either low, moderate, or 

 high hazard for Douglas-fir bark beetles. 

 These stand characteristics, and their values 

 for highest hazard, are: 



• Stand basal area - greater than 250 

 square feet per acre 



• Percent Douglas-fir - greater than 50 

 percent 



• Average stand age - greater than 120 

 years 



• Average dbh of Douglas-fir - greater than 

 14 inches 



Although Douglas-fir bark beetle and other 

 bark beetle hazard-rating systems can 

 indicate the stands most likely to be attacked, 

 they cannot indicate when such stands will be 

 attacked. 



Management of Douglas-fir bark beetle 

 generally falls into 2 broad categories, 

 silvicultural control or direct control {Schmitz 

 and Gibson 1996). Silvicultural control is 

 based on changing the stand conditions so 

 they are less attractive to bark beetles; 

 without these changes there is a tendency for 

 reoccurrence of attacks until the bark beetles 

 themselves have altered the stand conditions, 

 often to the detriment of old-growth structure 

 in Douglas-fir stands. Periodic thinnings can 

 reduce the density of Douglas-fir and the 

 overall proportion of bark beetle-susceptible 

 trees, but caution must be exercised due to 

 the impact thinning can have in promoting 

 damage by other pathogens, particularly the 

 root diseases. Timely salvage of windthrown 

 or otherwise-damaged trees removes high 

 quality brood trees. Without the salvage of 

 such trees, beetle populations can build 

 quickly and make successful attacks on 

 adjacent, standing trees. 



• Red-Brotm Butt Rot 



Red-brown butt rot, caused by the root- 

 infecting pathogen Phaeolus schweinitzii, is a 

 very common disease in older stands. Any 

 conifer can be a host, but it is found most 

 often in mature Douglas-fir. Instead of 

 affecting trees in expanding mortality centers, 

 as root diseases such as Armillaria typically 

 do, red-brown butt rot tends to affect trees on 

 an individual basis (Hansen and Lewis 1997). 

 The fungus can, however, cross from tree to 

 tree at root grafts and contacts. Most 

 damage occurs in stands older than 80 years 

 of age. The pathogen infects via small roots 

 and causes decay in the interior of roots. 

 This decay often extends into the butt log an 

 average of about 8 feet, making such trees 

 much more susceptible to stem collapse or 

 windthrow. Since such trees are most often 

 green when they fall, they can provide prime 

 habitat for Douglas-fir bark beetle. 

 Management options are limited; rotations 

 can be shortened in order to minimize loss of 

 merchantable volume and structural integrity, 

 or less-affected host species can be 

 emphasized. 



• WViite IHne BlUter Rmtt 



Western white pine has declined as a 

 component of the species mix in which it 

 historically occurred on Swan River State 

 Forest. The primary cause is white pine 

 blister rust, a disease caused by the 

 nonnative fungus Cronartium ribicola, which 

 can infect and kill western white pine of all 

 ages and sizes. Large dominant or co- 

 dominant western white pine that become 

 infected by blister rust are often top-killed 

 since the fungus first infects via needles, then 

 grows down the infected branch till it infects 

 and girdles the bole. The portion of the 

 crown above such a bole infection will die 

 once the stem is girdled. 



Retention of various numbers of mature, 

 seed-bearing western white pine is 

 encouraged in order to maintain genetic 

 diversity of the species and promote natural 

 regeneration where possible (Scliwandt and 

 Zack 1996). Once mature western white pine 

 are top-killed by rust, however, their seed- 

 producing capacity is often very limited or 

 eliminated, and such trees can then be 

 considered for salvage or retention as snags 



Cilly Bug Salvage Timber Sale Project 



Page D-3 



