2004 Forest Health Protection and State Forestry Organizations WEB July 2010

Kenneth E. Gibson Management Guide for USDA Forest Service, Mountain Pine Topics

Management 1 ponderosae Hopkins Life History 2

Lodgepole pine 2 (LPP): Direct The mountain pine Most  Lodgepole pine Control beetle is the most frequently Ponderosa pine  aggressive, LPP: Hazard Rating 3 killed hosts in  Whitebark pine the Northern persistent and  Limber pine destructive bark LPP: Silvicultural 7 and Central  Western white beetle in the Control Rocky Mountains: pine western United Semiochemicals & 10 States and Canada. baiting Natural Controls 11

Ponderosa pine 12 (PP) Manage by suppression and prevention Hazard Rating Because outbreaks usually develop The strategy of preventive PP: Silvicultural 13 in mature to over mature forests, management is to keep beetle Control especially in lodgepole pine, large populations below injurious levels by reserves of these forests pose a constant limiting the ’ food supply Western White Pine 13 hazard in areas climatically favorable through forestry practices designed to Whitebark Pine 14 for the mountain pine beetle (MPB). maintain or increase tree/stand Thus, "storing" mature/over mature resistance. Preventive management Other Reading 14 trees on the stump should be addresses the basic cause of epidemics, Field Guide discouraged, or at least the risk of such which is stand susceptibility, and is should be realized. In addition, considered the most satisfactory long- Management Guide management plans for reserved areas, term solution. It includes a Index such as parks and wildernesses, should combination of hazard rating, priority consider the need for protection against setting, and silvicultural manipulations. destructive outbreaks. The economic protection costs. Situations where Key Points impact of tree mortality is largely MPB instead of forest managers set  Use hazard rating to dependent on the effects of epidemics priorities and dictate management set treatment on allowable cut, regeneration of options should be avoided. In contrast, priorities affected areas, and increased fire. suppression of MPB populations, that is Management must focus on forests killing them by various methods of  Prevent outbreaks and not MPB. Management should direct control; treats only one symptom by regenerating alter stand conditions that favor buildup of the problem (too many beetles). mature lodgepole of beetle populations. However, Effects are usually, therefore, only  Thinning can help alternative strategies for reducing temporary. When proper1y used, direct losses from MPB must emphasize control might be effective both in  High value trees are biologically sound silviculture that reducing the rate of the spread and afforded temporary includes concern for other resource intensification of infestations; but protection using values. should be considered only a “holding pesticides Basi cally, there are two action” until susceptible stands can be approaches to reducing losses from altered silviculturally. MPB in pine forests: (1) long-term (preventive) forest management, and (2) direct control. Page 2 Back to menu Mountain Pine Beetle 4.2

Life History Mountain pine beetle over winters long. are laid along each side of mostly as larvae beneath (or within) the the gallery in individual niches. Both inner bark of host trees. Occasionally, niches and galleries are tightly pupae and callow adults may also packed with partially digested woody overwinter. In most lodgepole and particles, or frass. Eggs hatch and ponderosa pine stands, larvae pupate at larvae feed until freezing temperatures the ends of their feeding galleries in late cause dormancy. Larvae go through spring. Adults emerge and attack from four instars before pupating (Amman about early July through August and Cole 1983). depending on elevation and temperature. Egg galleries are more or less straight and vertical and may be up to 30 inches

Mountain Pine Beetle Life Cycle 4.2 Back to menu Mountain Pine Beetle Page 3

Controlling MPB in lodgepole pine Suppression Direct Control lodgepole pine stands need to be Direct control is expensive in time, prioritized on economic, or other effort, and resources. In spite of its long criteria; and control applied only to the history, there is no general agreement most valuable stands. These stands In order to be among scientists and foresters must be resurveyed yearly, and as soon effective, regarding its effectiveness in reducing as newly attacked trees are discovered, suppression losses. Operational activities in Canada a decision made on the feasibility of should be based indicate that direct control can be a control action. If control action is on the following temporarily sound strategy and that feasible, direct treatment is applied principles: tactics can be developed to implement involving sanitation cutting, controlled it. burning, single-tree treatment, or a 1. Early detection Since direct control is expensive, it combination of these methods and control is usually prohibitive to treat all (Safranyik 1982). action over the entire infested infestations. Therefore, susceptible area within one to two years. 2. Continue control work as long as necessary. 3. Thorough Methods to kill beetles under the bark: treatment and 1. Pesticides (systemic, bark-penetrating) on unbaited or follow-up pheromone-baited trees. Chemical control by spraying standing surveillance and/or fallen trees provides only a holding action at best until the highly susceptible trees can be removed. Tree mortality will probably result despite any immediate success of direct control measures. Because stand susceptibility is not changed by this management option, reinfestation will occur (Cole and Amman 1980). This type of treatment might be more suitable for treating isolated spot infestations, especially in remote locations or in areas where logging is not possible. 2. Heat (burning, solar). 3. Mechanical (debarking process). 4. Water (sprinkling, submersion). Page 4 Back to menu Mountain Pine Beetle 4.2

Individual Tree Methods to protect trees from fatal attacks Protection 1. Lethal trap trees baited with pheromone and treated with Preventative sprays insecticide. can protect high-value 2. Protective chemicals. Although carbaryl treatments provided the trees in campgrounds, picnic areas, visitor standard preventive measures for more than 25 years, and was centers, around the only chemical registered for most of that time; pyrethroid permanent and insecticides have been recently tested and registered, and now summer homesites and provide an alternative to the use of carbaryl. administrative areas. 3. The anti-aggregative pheromone, verbenone, has been tested and registered as a preventive treatment. Results have not Shade and aesthetics been as reliable as chemical insecticides, but may be a can be protected for up reasonable alternative in some situations. to 2 years with one application of water- based carbaryl spray prior to beetle flight (Gibson and Bennett 1985) Prevention Management objectives should be determined by proximity to beetle directed toward preventing, or at least populations. substantially mitigating, development To date, several hazard rating Shore and of epidemic beetle infestations. Once systems have been developed based on Safranyik Hazard populations increase to an epidemic climatic, tree, and stand variables that Rating System status and outbreaks become as large as have significant effects on both beetle experienced during the 1970's and early survival and distribution. That is, tree Has three distinct 1980's, management of beetle age, size, stand structure, phloem facets: populations, as well as other resources, thickness, climatic conditions, and tree  a susceptibility becomes more complicated. growth all determine stand index, susceptibility. Such site factors  a beetle pressure Hazard rating: influence amount of tree and volume index, Recurrent depredations by MPB loss within stands.  a risk index. allow the forest manager less than a 50 The system formerly used in the percent (perhaps as low as 25 percent) Northern Region was developed by chance of growing lodgepole pine to a Amman and others (1977) and involves 16-inch diameter in unmanaged stands. a 3-point rating of each of three factors: Risk index is a Two commonly asked questions are: (1) climate (elevation/latitude), (2) combination of (1) which lodgepole pine stands are average age of lodgepole pine in the susceptibility index most susceptible to mountain pine stand, equal to or greater than 5 inches and beetle pressure beetle outbreak, and (2) how many d.b.h., and (3) average d.b.h. of the index and is a measure of a stand's trees will be killed, or how much lodgepole pine in the stand, equal to or relative likelihood of volume loss will occur, if a stand greater than 5 inches d.b.h. Currently in sustaining damage becomes infested? our Regions, we most often from beetle attack in Susceptibility of stands to MPB recommended a hazard-rating system the near future. Risk depredation is determined by hazard developed by Shore and Safranyik index is a number, and risk rating stands. Generally, (1992). Similar in some respects to the between 0 and 100. Higher numbers, "hazard" is defined as the likelihood of one described by Amman, and others represent higher an outbreak within a specific time (1977), it is more definitive in its use of probability of period and is a function of stand more detailed stand information, and it infestation. conditions. “Risk" defines expected incorporates data relative to nearby loss should an outbreak occur and is beetle populations. 4.2 Back to menu Mountain Pine Beetle Page 5

Calculating the Stand Susceptibility Index

To determine a stand's risk index, determine first its susceptibility index using stand Susceptibility data in the following relationship: The susceptibility index will range from 0 to 100. index is a measure Highest values indicate the most susceptible stands. of stand characteristics Susceptibility Index (S) = P x A x D x L where: which describe their P = Percent of susceptible pine basal area attractiveness to A = Age factor beetles and is based on four D = Stand density factor variables: L = Location factor 1. Susceptible host P is calculated: Average basal area per hectare of LPP > 15 cm d.b.h. x 100 basal area (as percent of stand Average basal area per hectare all species > 7.5 cm. d.b.h. basal area), (Note: Metric units must be used in formulas to assure appropriate table values are 2. Age of dominate obtained.) and codominant host, 3. Stand density, and 4. Location (latitude, Age of dominant or co-dominant LPP Age Factor longitude and Age factor elevation). from table: < 60 years 0.1 61-80 years 0.6 > 80 years 1.0

Stems per Hectare Density (all species > 7.5 cm d.b.h.) Factor Density factor < 250 0.1 from table: 251-750 0.5 751-1,500 1.0 1,501-2.000 0.8 2,001-2,500 0.5 > 2,500 0.1

There are three possible location factors, based on a combination of longitude, latitude and elevation. Location factor is determined from the formula Y = [24.4 longitude] -[121.9 latitude] -[elevation (in meters)]+ 4545.1. For most areas on a District, and perhaps over a Forest, the location factor, once determined, will remain constant.

Y Location Factor > 0 1.0 between 0 and -500 0.7 < -500 0.3 Page 6 Back to menu Mountain Pine Beetle 4.2

Calculating the Beetle Pressure Index Beetle pressure index is related to the size and proximity of MPB population being rated. Determine first the size category from the following table:

Number infested trees outside Number infested trees inside stand stand (within 3 km) < 10 10-100 > 1 00

Beetle pressure < 900 Small Medium Large index is related to size and proximity of nearest 900-9,000 Medium Medium Large mountain pine beetle population. Both relative abundance of > 9,000 Large Large Large beetles and their nearness to the stand Now, use following table to determine beetle pressure index: for which risk is being determined will influence that stand's likelihood of being Relative Infestation Distance to Nearest Infestation (km) infested. Infestation Within 0-1 1-2 2-3 3-4 4+ Size Stand Beetle Pressure Index (B) Small 0.6 0.5 0.4 0.3 0.1 0.06 Medium 0.8 0.7 0.6 0.4 0.2 0.08 Large 1.0 0.9 0.7 0.5 0.2 0.10

Risk Index:

Having determined both susceptibility index (S) and beetle pressure index (B), we can now calculate risk index (R) from the relationship:

R = 2.74 [S1.77e-0.0177S][B 2.78e -2.78B] Where: e = Base of natural logarithm = 2.718 B = Beetle pressure index S = Susceptibility index

Alternatively, Risk index can be found in the table on page 6. Risk index will be a number between 0 and 100. The highest numbers represent stands that would receive the most damage from beetles in the near future 4.2 Back to menu Mountain Pine Beetle Page 7

Risk Index Table Based on Susceptibility Index (S) and Beetle Pressure Index (B)

S Beetle Pressure Index (B) 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Risk index 10 <1 <1 2 3 5 6 7 8 8 8 is a relative measure of a 20 <1 2 6 10 14 18 20 22 24 24 stand's likelihood 30 <1 4 10 17 24 30 35 39 40 41 of being infested in the near future 40 1 6 14 24 33 42 49 54 56 57 -generally less than 3 years. 50 1 7 18 30 42 52 61 67 70 71 Because it includes beetle 60 2 9 20 34 48 61 70 77 81 82 pressure, a dynamic statistic, 70 2 10 22 38 53 67 78 85 89 91 it should be updated every 80 2 10 24 40 56 71 82 90 95 96 couple of years.

90 2 10 24 41 58 73 85 93 98 99

100 2 11 25 42 59 74 86 94 99 100

Models to predict stand losses Rate of Loss Model Risk index is not a predictive McGregor 1983) to determine an measure, per se, but does show a approximation of loss should To approximate particular stand's likelihood of infestation occur. This model mortality in high- infestation relative to others predicts tree and volume loss over risk stands: evaluated. In a follow-up study, time and helps set priorities for  Available as part Shore, and others (2000) developed entering high-risk stands. The model of FINDIT a predictive model that could be is available as part of the FINDIT program used to estimate percent basal area program (Bentz 2000), and is also a  Subroutine of killed, based on stand susceptibility subroutine of the Forest Vegetation the Forest index. Their model is expressed as: Simulator (FVS). Vegetation Data used in determining stand Simulator. Percent basal area killed = 0.68 x susceptibility and risk may be stand susceptibility index obtained from surveys designed As an alternative, stands specifically for determining stand determined to be of highest risk susceptibility, timber inventory, or could be subjected to analysis using regular stand exams. the Rate of Loss Model (Cole and Page 8 Back to menu Mountain Pine 4.2

Silvicultural Alternatives: Even-aged lodgepole pine stands Type conversion: loss reduction practices (D. M. Cole Type conversion can be an attractive 1978). Salvage cutting should be choice when most objectives of carefully planned and administered as a management can be met equally well conscientious silvicultural practice to with different forest types. Even though protect other resource values. Time the mountain pine beetle appears to infest between tree killing and salvage cutting the lodgepole component of mixed stands should be minimal to prevent wood as readily as pure stands, the overall deterioration. This should be done stocking and wood production would be before beetle flight or it won't be higher. Achieving a mosaic of age effective in protecting trees in the classes and tree species in stands creates cutover adjacent stands. a minimum area susceptible to the beetle, making fast removal and/or application Sanitation cutting of direct control action more feasible. of highly preferred large-diameter, Shortened rotation This operation takes careful long-range infested trees from high-hazard stands is a viable option planning, good roads, markets, and above may slow rate of mortality. However, when lodgepole pine is the desired all, time. sanitation cutting will not significantly species and a Clearcutting in small- to moderate- alter stand structure, and beetles will seek smaller tree size sized blocks creates age and size mosaics out and infest residual, preferred large- can be grown within extensive pure even-aged stands diameter lodgepole pine unless all which would still and is a highly recommended practice preferred trees are cut or the stand satisfy product (Amman 1976). Timely surveys and structure is altered. Surveys to inventory requirements and maps of stand growth and volume, site stand structure, diameter-phloem economics of the quality, and other risk-related factors distribution, and growth of residual operation such as phloem (inner bark) thickness, lodgepole pine may permit successful elevation, latitude, stand structure and cutting; and prevent, or greatly reduce, form, composition, and forest type are beetle infestation for several years. essential for clearcuts to be effective. Sanitation cutting is expensive and must Schedules for clearcutting as a be carefully coordinated to prevent preventative measure should be spread of beetles into other stands along coordinated with other multiple-use haul roads or from infested log decks at management objectives. In areas where sawmills. Sanitation cutting must also probability of loss is high, future damage take into account the presence of dwarf can be reduced by directing regeneration mistletoe or cutting may leave too many to alternating species among blocks or to infected residuals. Salvage, or a mixed species within blocks (D. M. Cole combination of sanitation/salvage, should 1978, Cole and Amman 1980, McGregor be used with caution in some stands. and Cole 1965). Residual stands should be managed to meet objectives for growth, maximum Salvage and sanitation cutting: stocking levels, and species composition. In practice, salvage and sanitation Salvage works best where epidemics are logging is favored over individual tree in early stages, in well-stocked stands treatment because it is more cost with a relatively minor component of effective. Also, salvage operations host species, and generally confined to utilize infested timber and reduce both operable ground with access in place. the number of beetles and their potential food source. Individual tree treatments Stocking control: do not yield any salvage value and it is This is extremely important in pure, difficult to thoroughly treat large areas even-aged lodgepole pine stands. It (Safranyik 1982). allows maintenance of good stand vigor Salvage and sanitation cutting and the direction of stand growth toward should be adjusted either directly by moderate tree sizes and rotation timber economics or indirectly through objectives (D. M. Cole 1978). protection of other resources to qualify as 4.2 Back to menu Mountain Pine Beetle Page 9

Stocking control by age 25 (preferably Through stocking control, by age 15) to a spacing of about 10 by diameter/phloem thickness 10 feet results in culmination of mean distributions could be managed to annual increment on medium to good favor those not preferred by MPB. sites at about age 80 with average Alternatively, early stocking control stand diameters of about 20 inches and managed practices for increasing d.b.h. Additional thinning rate of growth (thinnings, genetic (commercial thinning would prolong improvements, and fertilization) could the culmination of CAI/MAI from increase tree vigor so that present age/ about 80 years to probably 120-130 size limits of tree susceptibility would years. Growth decline and MPB not be restrictive (Safranyik 1982). infestation could probably be prolonged for a number of years through early thinnings.

Photo of stocking control by thinning can make a stand less attractive to MPB.

Silvicultural Alternatives Pure, uneven-aged lodgepole pine stands and mixed-species stands

Stocking control, clearcutting, of the site. However, value of the and salvage cutting volume removed must exceed removal For uneven-aged and mixed costs unless indirect benefits of beetle species stands preventive practices management warrant subsidization. Partial Cutting mentioned for pure, even-aged may be useful where: lodgepole pine stands are also Partial cutting feasible. For example, mature uneven Partial cuts can be used to  Clearcutting is not -aged or mixed-species stands with a advantage in order to reduce the losses compatible with significant component of large from impending outbreaks through multiple-use lodgepole pine in the overstory can be overwood removal, shelterwood, and objectives. clearcut. If already infested, mortality group selection. This method is  Combinations of can be lessened by salvage logging. especially attractive when mature forest and Immature, uneven-aged, and environmental and visual impacts openings are desired. mixed-species stands are candidates preclude clearcutting. However, for stocking control with species dwarf mistletoe infection and windfall  Regeneration after discrimination possible in mixed- clearcutting is susceptibility can be serious difficult. species stands (D. M. Cole 1978). drawbacks on some sites (Safranyik 1982). Amman (1976) concluded that Species discrimination partial cutting is an option where In older mixed-species stands we timber values are primary, but applies can discriminate against lodgepole only where: pine by cutting only the larger  a small portion of the lodgepole lodgepole. This can be considered a pine have larger diameter and valid practice in regulated forests only phloem thickness categories if the residual stand is of sufficient conducive to beetle population vigor and stocking to maintain stand buildup, growth near the yield capability level (Continued on page 10) Page 10 Back to menu Mountain Pine Beetle 4.2

Considerations for Partial Cutting in Lodgepole Pine Stands Bollenbacher and Gibson (1986) have described additional conditions in which partial cutting may be desirable or preferable to regeneration harvests. If the decision has been made to conduct partial cuts, or "sanitation thinning," as a part of an overall management strategy, the land manager must choose stands where this technique will be most successful. Following is a list of site attributes and considerations to use when evaluating a lodgepole pine stand as a candidate for sanitation thinning. 1. Site productivity: A favorable soil moisture regime will likely add to the probability of an increase in growth and vigor of the crop trees. 2. Slope: Generally treat stands on tractor ground less than 35 percent to limit residual stand damage. 3. Average stand diameter: Choose stands where average d.b.h. exceeds 9 inches with less than 350 trees over 5 inches d.b.h. per acre. These stands will be more economical to log and will sustain less residual stand damage. 4. Age: Consider stands that are greater than 60 and less than 125 years old. 5. Current basal area: Stands should have at least 130 square feet per acre to be an economical logging chance. 6. Elevation: Consider only those stands lower than 6,000 feet. Stands at higher elevation (in northwest Montana) are generally lower risk due to a shorter growing season. 7. Wind firmness: In relation to topography, choose the most sheltered slope positions, as identified by Alexander (1975). 8. Present beetle infestation rate: Choose stands with a present infestation rate of 10 percent or less. Higher levels may result in excessive mortality in leave trees if logging is not completed prior to the next beetle flight. 9. Tree vigor: Choose stands with crop trees having a live crown ratio of 30 percent or greater. 10. Other resource objectives: Consider only those stands where other resource objectives may not be met through regeneration harvesting.

(Continued from page 9) Windthrow in relation to High windfall risk  residual trees would be prescribed cutting situations numerically adequate and Lodgepole pine is generally considered susceptible to windthrow,  Ridge top vigorous enough to maintain stand productivity. and the risk increases when stocking  Moderate to steep is reduced through partial cutting middle south– and Partial cuts in a mixed-species (Alexander 1975). Root system west-facing slopes stand, just coming under attack, might development varies with soil and not protected to be justified if removing high-risk stand conditions. On deep, well- windward, and all lodgepole pine in mixed-species drained soils, trees have a better root upper south-and stands would protect adjacent, un­ system than on shallow or poorly west-facing infested lodgepole pine stands. That drained soils. slopes. might only be applicable in the With the same conditions, the situation where lodgepole pine in the denser the stand, the less wind firm  Saddle on ridge mixed-species stand was of higher risk are individual trees because trees that tops. than that in the adjacent pure stand develop together in dense stands over and infestation of the mixed-species long periods of time, support each stand posed an undue risk to adjacent other and do not have roots, boles, and stands of lower susceptibility (D. M. crowns to withstand exposure to wind Cole 1978). if opened drastically.

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The risk of windthrow is also greater windward that can funnel wind into on some exposures than others. The the area. risk of windfall in these situations is These guides should be carefully increased at least one category by considered in assessing the efficacy of Moderate windfall such factors as poor drainage, shallow any intermediate or harvest cutting soils, and defective roots and boles. prescription for lodgepole pine stands, risk situations All situations become high risk if including those aimed at preventing or  Valley bottoms exposed to special topographic ameliorating mountain pine beetle parallel to situations such as gaps and saddles in effects. prevailing winds. ridges at higher elevations to the  All lower and gentle middle north- and west-facing slopes Low windfall risk situations not protected to the  Valley bottoms except where parallel to prevailing winds, windward. and all flat areas.  Moderate to steep  All low and gentle middle north- and east-facing slopes. middle south– and  All lower and gentle middle south- and west-facing slopes west-facing slopes that are protected by considerably higher ground not far protected by to windward. considerably higher ground not far to windward.

Semiochemicals and Baiting Semiochemicals in stands scheduled for harvest. Relatively recent developments Strategies vary with infestation by Borden, and others, (1983, 1986, intensity, size of infested stand, and 1987) have shown MPB susceptibility or infestation status of semiochemicals ("message"-bearing surrounding stands. chemicals) can be effectively used to augment silvicultural practices Spot baiting designed to reduce stand Developed to eliminate small susceptibility. Semiochemicals are "spot infestations of less than about naturally occurring pheromones 30 trees, spot baiting will hold produced by attacking beetles, plus beetles in the infested group until host-produced volatiles, which in that group can be removed in a small combination result in mass attacks on patch cut Best used for isolated individual trees. Taking advantage infestations, effectiveness of this of this phenomenon, private industry strategy may be diminished if has synthesized, packaged, and is heavily infested stands are closer marketing the complex of MPB than a few miles. In this strategy, 2­ semiochemicals in the form of 3 susceptible trees are baited in the aggregative “tree baits” (Phero Tech center of the group prior to beetle

1987). flight. Following beetle flight, the Photo displays a funnel trap con- Semiochemical tree baits are entire group of dead and currently taining aggregative semiochemi- used in various strategies, in infested trees is removed. cals provides a means to assess combination with logging, to populations of MPB essentially contain beetle populations Page 12 Back to menu Mountain Pine Beetle 4.2

Mop-up baiting beyond cut-block borders. Once This strategy is used as a follow- again, trees are baited before beetle up action where needed in an area flight and the entire stand is removed previously treated. By baiting in a clearcut operation following susceptible trees at a 2 ½- chain beetle flight. interval (165 feet) around the treated spot, and any susceptible trees left Additional research with within the spot, beetles can be further semiochemicals has involved the use concentrated and removed in a post­ of anti-aggregative pheromones for treatment operation. stand protection, and a combination of attractive and anti-aggregative Grid baiting pheromones in "diversion" tactics. Grid baiting has shown good Though both strategies hold promise, results in containing beetles in we are probably a couple of years or infestations up to 50 acres in size. more away from their operational use. Managing non- With this technique, susceptible trees The anti-aggregation pheromone, timber values within the infested area are baited on verbenone, has shown promise as a The do-nothing policy a 2 ½-chain (165) feet) grid stand or individual tree protectant in may be a viable option throughout the stand. Care should be recent tests (Bentz, and others, 2002). on forested areas not included in commercial taken to bait no closer to cut boundary timber production. As than 165 feet to avoid beetle dispersal far as aesthetics are concerned, infestations (both far and close views) may have little impact on the viewer. However, dead timber Natural Control Factors can have an enormous impact on areas While beetles are developing generally thicker in large-diameter relative to recreation, within a tree, many factors of trees and is a function of past growth. wildlife, build up of mortality are reducing their numbers. fuel, fire hazard, and These factors consist of competition Climate plant succession. among larvae, parasites and predators, Although tree diameter and Therefore, a fire pathogens, cold temperatures, drying phloem thickness are major factors management program of the bark, and pitch. Several utilizing prescribed fires involved in the dynamics of MPB in combination with comprehensive life table studies of populations, epidemics can develop some "safe" wild fires, the beetle and its mortality factors, only in stands located where may be more including one 13-year study, showed temperatures are optimum for beetle appropriate and that none of these factors, either development. Climate becomes an ecologically more individually or in combination, overriding factor at extreme northern desirable than the no- regulate beetle populations. Survival action policy (Safranyik latitudes and at high elevations. At 1982). of beetles during epidemics is more these extremes, beetle development is closely correlated with tree diameter out of phase with winter conditions. and phloem thickness of their hosts Consequently, stages of the beetle than any other factor. that are particularly vulnerable to cold In general, the number of beetles temperature enter the winter and are produced in any one tree is directly killed. Because of reduced brood related to thickness and quality of survival, infestations are not as phloem (food for developing larvae), intense and fewer trees are killed as and rate of phloem drying—which is elevation and latitude increase. lower in larger trees. Phloem layer is 4.2 Back to menu Mountain Pine Beetle Page 13

Ponderosa Pine General site characteristics and earlier. On poorer sites, trees are damage usually 75 to 100 years old when an High stand density is directly outbreak first occurs. related to site quality, both of which are positively correlated with damage. Direct control Intensive competition between trees Most of the philosophies, in dense stands and its effect on tree methods, and materials used to resistance to beetle outbreak in the suppress MPB in lodgepole stands history of a second-growth stand can be used in ponderosa pine stands. usually occurs between ages 50 and Again, most direct control efforts 100 years, depending upon site should be considered a holding action Estimating mortality quality. Stands often sustain their until silvicultural treatments can be first serious infestation between 50 applied. Loveless (1981) Mortality and 75 years on better sites because Risk Rating system to they grow into a susceptible condition estimate anticipated mortality in ponderosa pine stands

Hazard Rating Stands Number of ponderosa pine killed in an Three stand characteristics affect (3) Stand Density infestation increases as: susceptibility to attack: (1) stand The more dense the stand within structure, (2) average d.b.h. of a given average diameter, the more  Average d.b.h. ponderosa pine component, and (3) susceptible it will be to severe beetle- decreases (down caused mortality. Hazard ratings for to about 6-8 stand density as expressed by average inches), basal area per acre (Stevens et at. stands in which average d.b.h. is greater than 5 inches are: more than 1980).  Site index 150 square feet per acre = high (3); 80 increases, (1) Stand Structure to 150 square feet per acre = moderate (2); and less than 80 square feet per Single-storied stands are most  age increases. acre = low (1). This will vary with susceptible to severe damage. They geographic area, with 120 BA/acre are most likely to become attacked being high risk in some stands. first and to suffer greatest mortality. Computing a stand hazard Such stands are given a hazard rating category is similar to that described of (3). Two-storied stands are rated for lodgepole pine. The three (2) since overstory trees are generally numerical ratings above for stand Stand Risk Hazard not as susceptible. Multi- storied characteristics are multiplied to obtain Value Rating stands have not been given a rating, a stand risk value. The hazard value but probably could be rated (1). will then be assigned a rating as 2-6 Low follows: (2) Average Diameter Schmid, and others (1994), As mean stand diameter confirmed Stevens earlier work and 8-12 Moderate increases, stand susceptibility also demonstrated that stand hazard, a increases. Stands greater than 1 10­ function of stocking, can effectively inch average d.b.h. are high hazard be reduced through commercial 18-27 High (3), those 6 to 10 inches are moderate thinnings. (2), and those less than 6 inches are low (1). However, more trees in the 6 - to 12-inch d.b.h. size classes will be killed once an infestation starts. Page 14 Back to menu Mountain Pine Beetle 4.2

Managing Silvicultural Alternatives ponderosa pine to minimize losses to Thinning of overstocked second- thinning in a small stand may not be MPB growth ponderosa pine stands can have successful if the stand is surrounded by a profound effect on beetle-caused un-thinned, infested stands. Finally, Year 1 mortality. An un-thinned stand stocked slash must be property disposed of, i.e.,  Determine at a basal area of 152 square feet per piled and burned or lopped and boundaries of area acre had 8 percent of the stand killed by scattered to prevent population to be included and mountain pine beetle in a 5-year period. buildups of pine engraver beetles (Ips arrange for A similar stand, thinned to 15- by 15­ spp.). Where limbs or tops more than 3 handling as a unit. feet spacing (80 square feet per acre inches in diameter are left, engraver  Salvage infested BA) showed only 0.2 percent mortality beetles may develop and infest trees over entire in the same period. In addition to surrounding green trees. area reduced mortality, thinned stands Stevens, and others (1974), have  Locate areas in showed a net growth (Sartwell and outlined a management program to which thinning is needed (through Dolph 1976). Maintaining stand basal minimize losses. See the sidebar at hazard rating area below 150 square feet per acre has right Using these guidelines, it may previously been effective in suppressing beetle take at least 3 years to implement the described). Begin outbreaks in the Black Hills (Schmid, program and significantly reduce thinning to BA of and others, 1994). A cooperative FPM- mortality. about 80 square Lolo National Forest study showed feet per acre. beetle-caused mortality was higher Natural control Year 2 where stand basal area exceeded 120 The same factors that affect MPB  Continue salvage. square feet per acre. in lodgepole pine pertain to ponderosa Cautions are issued, however, pine. However, severe low winter  Finish thinning. where thinning is used to manage temperatures probably do not kill as

Year 3 beetle populations. First, thinning has many beetles in ponderosa pine because no application where trees are in a of its thicker bark.  Salvage fringe area and widely spaced. Second, Year 4+  Maintain surveillance and Western White Pine salvage as needed. In the intermountain West, MPB is salvage logging, or partial cutting Year 10+ chronic in areas of residual mature usually does not stop the beetle from  Re-evaluate western white pine. Trees over 90 years killing residual mature western white treated area. Thin of age are susceptible and are pine in a stand. where necessary to frequently killed. Rarely does MPB Western white pine have not maintain low stand recently been intensively managed density. attack a western white pine under 10 inches in diameter unless there are because of blister rust depredations; extenuating circumstances—such as however, as rust-resistant plantations blister rust infestation, extreme dry begin to mature, we may learn thinning weather, or other stressing factor. to maintain low stand basal area will Infestations in unmanaged pockets of reduce mortality from MPB. At mature western white pine usually do present, we recommend harvesting not spread into surrounding stands of mature western white pine whenever lodgepole or neighboring ponderosa feasible. It is a gamble to store such pine trees. trees on the stump unless they can be Surveys and observations over the salvaged easily. years indicate that direct control, 4.2 Back to menu Mountain Pine Beetle Page 15

Whitebark Pine Although long known to be hosts Likewise, management efforts have of MPB, whitebark and limber pines been infrequently attempted on these have only recently begun to sites. There is, however, increased experience extreme amounts of beetle interest in protecting seed-bearing -caused mortality in the intermountain trees because of their importance to West. Currently, little is known about wildlife species, and because of beetle life cycle at higher elevations. recent efforts to develop rust-resistant It may well be longer than one year. programs.

Mountain Pine Beetle can be devastating in dwindling white- bark pine forests. Other Reading Alexander, Robert R. 1975. Partial cutting in old- Borden, J.H.; Conn, J.E.; Friskie, L.N.; Scott, B.E.; growth lodgepole pine. Res. Paper RM-136. Ft. Chong, L.J.; Pierce, H.D., Jr.; Oehlschlager, A.C. Collins, CO: USDA Forest Service, Rocky 1983. Semiochemicals for the mountain pine Mountain Forest & Range Experiment Station. 17 beetle, Dendroctonus ponderosae (Coleoptera: p. Scolytidae), in : baited tree Amman, Gene D. 1976. Integrated control of the studies. Canadian Journal of Forest Research. 13: mountain pine beetle in lodgepole pine forests. In: 325-333. Proceedings, XVI IUFRO World Congress, Borden, J.H.; Chong, L.J.; Lacey, T.E. 1986. Pre- Division II, Oslo, Norway. p. 439-446. logging baiting with semiochemicals for the Amman, Gene D.; McGregor, Mark D.; Cahill, Donn mountain pine beetle. Dendroctonus ponderosae, B.; Klein, William H. 1977. Guidelines for in high hazard stands of lodgepole pine. Forestry reducing losses of lodgepole pine to the mountain Chronicle. February 1986: 20-23. pine beetle in unmanaged stands in the Rocky Borden, J.H.; Ryker, L.C.; Chong, L.J.; Pierce, H.D., Mountains. Gen. Tech. Report INT-36. Ogden, Jr; Johnston, B.D.; Oehlschlager, A.C. UT: USDA Forest Service, Intermountain Forest 1987. Response of the mountain pine beetle, & Range Experiment Station. 19 p. Dendroctonus ponderosae Hopkins (Coleoptera: Amman, Gene D.; Cole, Walter E. 1983. Mountain Scolytidae) to five semiochemicals in British pine beetle dynamics in lodgepole pine forests. Columbia lodgepole pine forests. Canadian Part II: Population dynamics. Gen. Tech. Report Journal of Forest Research. 17: 118-128. INT-145. Ogden, UT: USDA Forest Service, Cole, Walter E.; Amman, Gene D. 1980. Mountain Intermountain Forest & Range Experiment pine beetle dynamics in lodgepole pine forests. Station. 59 p. Part I: Course of an infestation. Gen. Tech. Report Bentz, Barbara J. 2000. Forest and disease tally INT-89. Ogden, UT: USDA Forest Service, system (FINDIT) user manual. Gen. Tech. Report Intermountain Forest & Range Experiment RMRS-GTR-49. Logan, UT: USDA Forest Station. 56 p. Service, Rocky Mountain Research Station. 12 p. Cole, Walter E.; Amman, Gene D.; Jensen, Chester E. Bentz, Barbara J.; Kegley, Sandy; Gibson, Kenneth 1985. Mountain pine beetle dynamics in E.; Thier, Ralph. 2002. A test of nonhost tree lodgepole pine forests. Part III: Sampling and volatiles and verbenone for reducing the number modeling of mountain pine beetle populations. of mountain pine beetle-attacked trees. (In Press) Gen. Tech. Report INT-188. Ogden, UT: USDA Logan, UT: USDA Forest Service, Rocky Forest Service, Intermountain Forest & Range Mountain Research Station. Experiment Station. 45 p. Bollenbacher, Barry; Gibson, Kenneth E. 1986. Cole, W. E.; McGregor, Mark D. 1983. Estimating the Mountain pine beetle: A land manager's rate and amount of tree loss from mountain pine perspective. Forest Pest Management Report 86­ beetle infestations. Res. Paper INT-318. Ogden, 15. Missoula, MT: USDA Forest Service, UT: USDA Forest Service, Intermountain Forest Northern Region. 5 p. & Range Experiment Station. 22 p. Page 16 Back to menu Mountain Pine Beetle 4.2

Gibson, Kenneth E.; Bennett, Dayle D. 1985. Carbaryl Service, Pacific Northwest Forest & Range prevents attacks on lodgeple pine by the mountain Experiment Station. 8 p. pine beetle. Journal of Forestry 83(2):109-112. Schmid, J.M.; Mata, S.A.; Obedzinski, R.A. 1994. Loveless, Robert D. 1981. A hazard rating system for Hazard rating ponderosa pine stands for mountain western Montana ponderosa pine stands pine beetles in the Black Hills. Res. Note RM­ susceptible to mountain pine beetle. Missoula, 529. Ft. Collins, CO: USDA Forest Service, MT: Master of Science Thesis, University of Rocky Mountain Forest and Range Experiment Montana. 32 p. Station. 4 p. McCambridge, William; Amman, Gene D.; Trostle, Shore, T.L.; Safranyik, L. 1992. Susceptibility and Galen C. 1979. Mountain pine beetle. Insect and risk rating stands for the mountain pine beetle in Disease Leaflet 2. Washington, D.C.: USDA lodgepole pine stands. Information Report BC-X­ Forest Service. 7 p. 336. Victoria, B.C.: Forestry Canada, Pacific and McGregor, Mark D.; Cole, D. Michael (editors). 1985. Yukon Region, Pacific Forestry Centre. 12 p. Integrating management strategies for the Shore, T.L.; Safranyik, L.; Lemieux, J.P. 2000. mountain pine beetle with multiple-resource Suscpetibility of lodgepole pine stands to the management of lodgepole pine forests. Gen. Tech. mountain pine beetle: testing of a rating system. Report INT-174. Ogden, UT: USDA Forest Canadian Journal of Forest Research. 30:44-49. Service, Intermountain Forest & Range Stevens, Robert E.; Myers, Clifford A.; Experiment Station. 68 p. McCambridge, William F.; Downing, George L.; Phero Tech, Incorporated. 1987. Technical Bulletin: Laut, John G. 1974. Mountain pine beetle in front Mountain pine beetle management with tree baits. range ponderosa pine: What it's doing and how to Vancouver, B.C.: Phero Tech, Incorporated. 4 p. control it. Gen. Tech. Report RM-7. Ft. Collins, Safranyik, L.; Shrimpton, D.M.; Whitney, H.S. 1974. CO: USDA Forest Service, Rocky Mountain. Management of lodgepole pine to reduce losses Forest & Range Experiment Station. 4 p. from the mountain pine beetle. Forestry Tech. Stevens, Robert E.; McCambridge, William F.; Report 1.Victoria, B.C.: Canacian Forestry Edminster. Carlton B. 1980. Risk rating guide for Service, Pacific Forest Resource Centre. 24 p. mountain pine beetle in Black Hills ponderosa Safranyik, L 1982. Alternative solutions: Preventive pine. Res. Note RM-385. Ft. Collins, CO: USDA management and direct control. In: Proceedings, Forest Service, Rocky Mountain Forest & Range Joint Canada/USA Workshop on MPB related Experiment Station. 2 p. problems in western . Publication USDA Forest Service. 2007. Forest insect and disease BX-X-230. Victoria, B.C.: Canadian Forestry management guide for the northern and central Service, Pacific Forest Research Centre: 29-32. Rocky Mountains. USDA Forest Service, Sartwell, Charles; Dolph, Robert E. 1976. Northern Region, State and Private Forestry. Web Silvicultural and direct control of mountain pine Publication. http://www.fs.fed.us/r1-r4/spf/fhp/ beetle in second growth ponderosa pine. Res. mgt_guide/index.htm Note PNW-268. Portland, OR: USDA Forest

Publication Citation

Gibson, K. E. 2004. Mountain Pine Beetle Management. Chapter 4.2. Forest insect and disease management guide for the northern and central Rocky Mountains. USDA Forest Service, Northern Region, State and Private Forestry. 16 pp.

Available from USDA Forest Service, Idaho Department of Lands, and Montana Department of Natural Resources, and on-line at: http://www.fs.fed.us/r1-r4/spf/fhp/mgt_guide/index.htm

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