1. Vegetation Conditions 

The vegetation associated with the Butcher Knife Slate Study Area is typical of the vegetative 

communities in southwest Oregon described by Franklin and Dyrness (1973). One hundred or more 

years ago, most of the low to mid elevation forests of southwestern Oregon, including those of the 

Butcher Knife Slate Study Area were structurally and compositionally different from today’s forest. 

In those days, fire occurred as often as every 20 to 30 years. This occurrence was probably more 

frequent at the lower elevations and less frequent at the higher, wetter sites including riparian zones 

and north aspects. These fires were usually of low intensity and mostly ground fires that maintained 

the area in an early seral condition. Timber stand composition included white oaks, black oaks, 

madrone, ponderosa pine and scattered Douglas-fir trees. The forests were open, allowing one to see 

considerable distances in all directions, unlike the stands of today. There were few patches of dense 

seedlings, saplings and poles of white fir and Douglas-fir. The forests had a simpler structure and 

composition and were more resistant to insects and disease. 

Since the initiation of aggressive fire suppression, the in-growth of shade tolerant species has 

increased stand density to a point above what is considered an appropriate level for a healthy forest. 

Fire exclusion has allowed the more tolerant white fir and Douglas-fir to develop in dense 

understories over a large portion of the affected sub-watersheds. Fuel loads and ladder fuels have 

increased the risk of wildfire across the landscape. This dense stocking level is taxing the 

ecosystem’s resources making the competition between trees intense. Early seral tree species, such as 

white oak, black oak, ponderosa pine and sugar pine, have especially suffered under these conditions. 

This stressed environment creates favorable conditions for successful disease and insect attacks, a 

situation aggravated by recent drought. Trees killed by insects and disease are continuously adding to 

the fuel load and increasing the risk of catastrophic fire. 

a. Plant Series and Plant Associations 

Forests in the Butcher Knife Slate Study Area are primarily comprised of four Plant Series. The most 

common is Douglas-fir (46 percent of area), Tan Oak (21 percent of the area), and Jeffrey Pine. Less 

well-represented series include white oak with minor areas in Grand fir and White fir. Descriptions 

of the major Plant Series found in the Butcher Knife Slate Study Area can be found in “Forested 

Plant Associations of Southwestern Oregon” (T. Atzet, et al. 1996). The major Plant Series for the 

vegetation Study Area associated with Butcher Knife Slate Study Area are shown on Map III-6. 

 

Plant Associations are a system for classifying vegetation that provides useful clues to the sitespecific environment. In the classification system, a limited number of plants are considered indicator 

species. Different combinations of these indicator plants describe distinct associations and point to a 

unique set of environmental conditions. Plant Associations can help characterize the moisture 

regime, climate, soil chemistry, potential wildlife use, and vegetative management options for an 

area. Each Plant Association is named for the major overstory (dominant tree) species and understory 

(usually shrub or herb) species that are predicted at the climax stage of development for any given 

vegetation community. The climax is a stage in succession that occurs when a plant community is 

allowed to develop undisturbed for a long period and plant composition and structure reach a steady 

state that would be characteristic of the sites potential. 

b. Vegetative Seral Stages 

An important characteristic of vegetation is the seral stage. Most analyses have used successional 

stages; this is not appropriate for the southwest Oregon areas because of the frequent fire return 
intervals. Stand age averages only about 250 to 300 years. Ecologically, succession is classed as 

early successional, with the stand being composed primarily of pioneer species, the mid-successional 

stage, when the climax species begin colonizing stand and produce a lower tree layer. Latesuccessional stands are characterized by the dominance of the climax, and the decline of the pioneers, 

and climax stands are composed of climax, shade tolerant species. Stands in the Butcher Knife Slate 

Study Area, because of fires, typically only reach mid-successional condition. The pioneer species, 

such as Douglas-fir, still dominate the stands. 

For this analysis, seral stages have been identified as more meaningful, and have been defined by 

stand canopy closure and tree size. Early, mid and late seral stages have been recognized. Late seral 

stand are defined as canopy cover greater than 60 percent and average tree diameters greater than 21 

inches. Mid seral stands are defined as canopy cover greater than 40 percent but less than 60 percent 

and average tree diameters from 11 to 21 inches, and early seral stands are defined as canopy cover 

less than 40 percent. The table below is the result of combining these variables. 

Table III-11. Current Vegetation Conditions in the Study Area by Seral Stages 

Seral Stage 

Forest Service Managed 

Lands and Private Lands 

within Study Area 

Percent of Total 

Non-Forest 267 4.5 

Early or Non-Forest 2322 39.9 

Mid 2675 45.9 

Late 564 9.7 

Totals 5,830 100 

Summer storm events, being convective in nature, can produce intense rainfalls that can accelerate 

surface erosion on exposed soils. Movement of the Jet Stream in spring and fall can generate highvelocity winds at the surface. High winds combined with extremely saturated soils occasionally 

causes trees to be uprooted when they are directly exposed. “Windthrown trees” have been observed 

in the Butcher Knife Slate Study Area, typically near ridgetops, on the edges of insect centers, and on 

the edges of previous regeneration harvested stands. The degree and extent of this condition is not as 

severe or extensive as occurs elsewhere in the Pacific Northwest. 

c. Managed Stands 

Multiple-use resource management has long been practiced in the Butcher Knife Slate Study Area. 

Harvesting activities began in large tracts in the Butcher Knife Slate Study Area in the 1950s when 

the area was noted for its supply of large diameter ponderosa pine and sugar pine timber. 

As a result, in the Butcher Knife Slate Study Area there are acres of young, 20 to 60 year old mixed 

conifer stands. Seed certification and a better understanding of seed zones and sowing seed from 

appropriate elevation bands corresponding with out-planting needs began to occur in 1965. 

2. Forest Health 

Pathogens and insects are currently affecting forest conditions (i.e., forest health) throughout the 

Butcher Knife Slate Study Area. In particular, white pine blister rust (caused by the fungus 

Cronartium ribicola), Douglas-fir beetle (Dendroctonus pseudotsugae) Mt.ain pine beetle (D. 

ponderosae) western pine beetle (D. brevicomis), pine engraver beetles (Ips spp.), and the fir 
engraver (Scolytus ventralis) are currently influencing stand structure, stocking, and species 

composition in many stands. 

These agents will continue to affect stand development and succession into the future. While 

mortality in some stands may be attributable to a single pathogen or insect, it is more common to find 

several pathogens and insects working together in complexes. Their effects are greatly influenced by 

the tree species composition in affected stands, host ages, and history of other disturbances such as 

fire, wind, or timber harvest. 

Insects and pathogens affect ecosystem functions and conditions by physically altering or killing 

their host trees. This leads to changes in forest species composition and successional pathways, 

influences tree size, canopy cover, and stand structure, creates wildlife habitat, affects nutrient 

cycling, and influences fire behavior. Effects may be subtle or dramatic; insects and pathogens can 

influence the landscape, stand, or individual trees. Whether their effects are perceived as beneficial or 

detrimental is dependent upon management objectives, desired future conditions, and scale of 

activities. 

Insect and pathogen activity in the Butcher Knife Slate Study Area has increased since the turn of the 

century as a result of fire exclusion, introduction of exotic organisms, and extensive management 

activities. Most important effects have been increased stocking levels, changes in species 

composition, soil disturbance and compaction, creation of wounds and stumps, and lack of coevolved 

resistance mechanisms. 

a. Root Diseases 

Black stain root disease can be observed causing mortality of small groups of younger Douglas-fir, 

particularly trees in plantations that are less than 30-years-old. It is predominantly associated with 

roadsides, skid trails, and landings. Black stain is spread long distance by root-feeding bark beetles 

and weevils that are attracted to low vigor Douglas-fir. This includes trees growing in compacted 

soils as well as recently cut stumps and slash. The beetles carry spores of the fungus and introduce 

the fungus to the trees while the insects are feeding in the roots. 

Once established in the root system, black stain root disease can spread quickly to other trees via root 

grafting and contact. Susceptibility to black stain root disease usually decreases on a site once the 

trees reach 30 to 35 years old. However, it is possible to find black stain in older trees under stress. 

b. White Pine Blister Rust 

In the Butcher Knife Slate Study Area, white pine blister rust occurs throughout the ranges of its 

hosts, affecting sugar pine. High hazard locations where high levels of mortality may occur include 

large flats or stream sides where moist conditions generally prevail or on saddles or ridgetops where 

fog and clouds linger in the fall. Higher elevation sites in the Study Area are particularly vulnerable 

and the long-term survival of wild type five-needle pines is questionable in these locations. 

White pine blister rust is a branch and stem canker disease of five-needle pines. Damage includes 

mortality, topkill, branch dieback, and predisposition to attack by other agents, including bark 

beetles. 

C. ribicola is exotic; it has not coevolved with its hosts. The fungus is native to Asia but was 

introduced to British Columbia via Europe in 1910. It quickly spread throughout most of the range of 
five-needle pines in the West. It has substantially decreased populations of five-needle pines 

throughout their ranges. Its is a major killer of regenerating five needle pines and makes 

reestablishment of wild populations of these species on high hazard sites difficult or impossible. In 

many areas, the only natural hosts remaining in high hazard areas are large trees that have had their 

tops and numerous branches killed by the fungus. Trees in this condition are frequently predisposed 

to infestation by mountain pine beetle. 

The life cycle of the fungus takes four to five years to complete. The fungus is an obligate parasite 

and requires an alternate host in the genus Ribes, the gooseberries and currants. Yellow-orange 

pustules or blisters on pines produce aeciospores annually in the late spring. These thick-walled, long 

living spores are fairly resistant to radiation and desiccation; thus they are capable of long distance 

dispersal by wind. Aeciospores land on and infect the leaves of Ribes. Ribes leaves support annual 

infections that produce urediniospores in midsummer. Urediniospores infect other Ribes leaves and 

build up the population of the rust in local areas when conditions are somewhat moist. Basidiospores 

are produced on infected Ribes leaves in late summer and early fall and are disseminated via wind to 

pine needles where they germinate. These thin-walled, short-lived spores require cool temperatures 

and moist conditions for survival and germination; wet weather or low-lying clouds and fog in late 

summer and early fall increase the chance of successful movement from Ribes back to pine hosts. 

The distribution, frequency, and association of the hosts, as well as micro and macroclimatic 

conditions are important factors in the spread of the rust. Dense populations of Ribes increase the 

probability of having high production of basidiospores and infection of local pine populations. 

Certain Ribes species are more susceptible to infection than others. Large-scale weather events that 

bring moist conditions to a region influence levels of infection and long distance travel of fragile 

spores. Topographic features combined with microclimate, such as saddles or mountain tops where 

summer fog is frequent, locally influence infection. 

c. Bark Beetles 

Bark beetles such as Douglas-fir beetle and the fir engraver are common in the project area. These 

beetles are secondary agents that are attracted to weakened trees. They maintain their endemic 

populations by attacking stress-weakened trees in overly dense stands. They also take advantage of 

trees injured or weakened by fire and increases in mortality may be observed on the perimeters of 

burned areas. All sizes of trees can be attacked and killed by the fir engraver. 

Fir Engraver Beetle 

In recent years, fir engraver-caused mortality has been observed that is associated with drought 

stress, particularly in heavily stocked stands. This type of fir engraver-caused mortality has occurred 

in the watershed in small pockets. By killing trees, the fir engraver increases diversity in a stand and 

creates habitats for numerous organisms that depend on dead wood. Engravers also colonize down 

material and hasten its recycling by introducing wood decay fungi through the bark. 

The fir engraver completes one generation per year. Adult beetles fly and initiate new attacks 

between June and September, with peak activity in July and August. Females initiate attacks and 

after mating, each constructs an egg gallery perpendicular to the grain of the tree. Eggs are laid on 

both sides of this gallery, and larvae hatch within two weeks. Winter is passed in the late larval or 

pupal stage, and young adults mature by the following summer. 
Douglas-fir Beetle 

Small pockets of mortality caused by Douglas-fir beetle are found scattered throughout the Butcher 

Knife Slate Study Area. These pockets are most often associated with stressed trees or very localized 

windthrown trees. 

 

The Douglas-fir beetle normally breeds in weakened or down trees. In certain instances when down 

or weakened host material is abundant, beetle populations can build to high levels and nearby 

standing trees may be attacked and killed. Outbreaks are sporadic and usually of short duration, 

subsiding after two or three years. Since the Douglas-fir beetle has a strong preference for the largest 

trees in a stand, even short-duration outbreaks can have a significant effect on stand structure and gap 

formation. 

The Douglas-fir beetle has one generation per year. Adult flight usually takes place in the spring or 

early summer. Female beetles initiate attacks on suitable host material and construct long egg 

galleries beneath the bark. The eggs hatch within one to three weeks and young larvae feed in the 

cambium. Later in the larval stage, the larvae enter the outer bark where they construct pupal 

chambers. The winter is spent in the outer bark, either in the late larval, pupal, or adult stage. Those 

insects over-wintering as adults will be the first to fly in the following spring, and may re-emerge, fly 

again, and establish a second brood in late June or July. 

Pine Bark Beetles 

Mountain pine beetles have recently killed scattered large-diameter sugar pines across the Butcher 

Knife Slate Study Area; western pine beetle and mountain pine beetle have also killed several large 

ponderosa pine. Mortality appears to have been occurring for several years. Attacks by Ips spp. have 

resulted in topkill of larger pines and mortality in scattered pockets of sapling and pole-sized trees. 

Trees attacked by the pine bark beetles are generally killed. Attacks may occur on either individual 

trees or groups of trees. In the endemic situation, the beetles attack trees that are under stress due to 

competition with other trees, weakened by pathogens, injured by fire, or are otherwise debilitated. 

Periodically, large-scale outbreaks can occur and infestations can extend into stands of healthy trees. 

Trees infested by the pine bark beetles provide temporary food sources for woodpeckers and other 

insectivores. Infestation by western pine beetle sets the stage for other agents, such as woodborers 

and decay fungi that are involved in the recycling of nutrients back into the soil. 

In ponderosa pine, the mountain pine beetle is generally associated with fairly young trees (75 to 100 

years old) and acts as a thinning agent in denser stands. This thinning may be fairly irregular and may 

involve sizable groups of trees but is generally far less dramatic than is the case when beetles infest 

lodgepole pine. 

In the case of five-needle pines where host trees are usually scattered among other tree species, the 

mountain pine beetle will kill large scattered dominants or create small holes in stands as it attacks 

pines stressed by competition, white pine blister rust, or other factors. 

The western pine beetle serves as a key mortality agent for ponderosa pines weakened by the effects 

of old age, drought, diseases, or competition with other trees. Successful attacks result in death of the 

host tree. Occasionally, groups of trees are killed, especially when growing under crowded 

conditions. Since larger trees are generally preferred, the western pine beetle can dramatically alter 

the character of a forest that comes under attack. Stand structure can be altered and gaps can be 
created in the stand as the bark beetles kill the larger trees, either singly or in groups. In those 

instances where ponderosa pine occurs in mixed stands with firs, the western pine beetle can 

accelerate the successional process by selectively removing the early seral species from the stand. 

Pine engravers are associated with logging slash and windthrown material. Pines broken or knocked 

down by snow may favor conditions for Ips bark beetles. On occasion, beetles can spread from this 

down material into standing trees and can cause significant tree mortality, especially in thickets and 

in young recently thinned stands. Tops of large trees may also be killed. Ips beetles help to accelerate 

the recycling of woody material by introducing wood decay fungi into host sapwood. Pine engravers 

also create gaps and introduce diversity into dense stands when they kill groups of young pines. 

The mountain pine beetle has one generation per year. Adult flight occurs between July and 

September, with eggs laid beneath the bark immediately after the tree is colonized. The eggs hatch 

within 10 to 14 days and larvae begin feeding in the cambium. The winter is spent in the late larval 

stage and pupation occurs in the spring or early summer. By mid-summer, callow adults develop and 

new adults are ready to emerge shortly thereafter. 

Pine bark beetles are generally associated with trees under stress from such factors as competition 

with other trees, infection by dwarf mistletoe, root disease organisms, or other pathogens, or 

infestation by other insects. During drought periods, all of these factors become more important, and 

mountain pine beetle activity is at its greatest. Second-growth ponderosa pine stands are likely to be 

infested when growth rates of codominant trees are less than 3⁄4-in. in diameter for the last decade. 

Other species of pine are likely to be killed by mountain pine beetle when growing under dense stand 

conditions. 

The western pine beetle completes two generations in one year. Adult beetles fly in early June and 

late August. Female beetles locate a suitable host and initiate attacks by burrowing through the bark. 

They release an airborne chemical (pheromones) that attracts other beetles and leads to concentrated 

attacks on the host tree. 

In times of particularly warm weather, these beetle-produced attractants can lead to mass attacks on 

several trees in a group. Each female lays about 60 eggs in individual niches cut in the sides of the 

egg gallery. These eggs hatch in two weeks and young larvae feed initially in the phloem, later 

moving into the middle bark where most development takes place. After four larval stages, the 

insects turn into pupae and then adults. 

Pine engraver beetles can complete several generations in one year depending on the temperature, 

leading to rapid outbreaks when conditions are right. Adults emerge from their over-wintering sites 

in late April and fly in search of fresh slash or windthrown material. The males initiate attacks and 

produce attractants, which draw other males and then females onto the same host material. In the 

case of I. pini, the males are joined by as many as four females and after mating in a nuptial chamber 

created beneath the bark by the male, each female constructs an individual egg gallery. Eggs are laid 

in these galleries, and larvae develop quickly and transform into pupae by mid-June. New adults are 

ready to emerge and fly by the end of July. If this second generation does not find fresh slash or 

windthrown material, it is likely to infest standing trees. The second generation is completed by midto late-September. Some new adults over winter beneath the bark of their host while others emerge 

and fly off to hibernate in the forest.