United States Department of Agriculture Forest Service Intermountain Forest and Range Experiment Station Ogden,UT84401 Research Note INT-333 July 1983 ## ABSTRACT Diameter-limit and leave-tree cuts were tested as ways to reduce orminimize lodgepole pine losses to the mountain pine beetle.In the first year after treatment,loss reductions were proportional to the intensity of cut.According to the Rate of Loss Model, the 100-leave-tree cut was the best deterrent of recurring infestation,measured as amountof losses and length of time. The 100-leave-tree cut also should provide the bestregeneration and has the added benefit of reducing dwarf mistletoe infection. KEYWORDS:mountain pine beetle,Dendroctonus ponderosae,lodgepole pine,Pinus contorta var.latifolia,harvest strategies Principal Entomologist,Population Dynamics of the Mountain Pine Beetle Research Work Unit,Intermountain Forest and Range Experiment Station,Ogden,Utah. Entomologist,Forest Pest Management,Rocky Mountain Region, USDA Forest Service,Lakewood,Colo. CANuSA Entomologist,Forest Pest Management,Boise Zone Office Intermountain Region,DA Forest Service,Boise,Idao 1271507 ## Harvesting 186153 Strategies for Management of Mountain Pine CSX Beetle Infestations in Lodgepole Pine: Preliminary Evaluation, East Long Creek Demonstration Area, Shoshone National Forest,Wyoming Walter E. Cole, Donn B. Cahill,2 and Gene D. Lessard3 East Long Creek in the Shoshone National Forest is one ofa seriesofdemonstration areaprojects that used management alternatives derived from research (Cole and Cahill 1976) and small-scale tests (Cahill 1978;McGregor and Cole,in press) in an attempt to reduce or minimize lodgepole pine (Pinus contorta var. latifolia Engelm.) losses to the mountain pine beetle (Dendroctonus ponderosae Hopkins). The objective of this initial large-scale application of management alternatives was to prevent undue losses of lodgepole pine by changing or reducing the food supply of the mountain pine beetle,and also to manipulate the stand to grow at or near optimum site capacity with continued prevention of large losses to the beetle. Some constraints on the project were to protect or enhance key resource values,remove merchantable material through a commercial timber sale,developper ment,improve forest cover growing conditions through disease control and stocking to attain timber production potentials on regulated lands,and develop a costbenefit analysis for each strategy.This report is limited to the reaction of themountainpine beetle and tree growth response the first year after cutting. Future efforts to manage stands to prevent losses to the beetle must be made before the beetle epidemic cycle.East Long Creek Demonstration Area provided this opportunity. ## STUDY AREA The East Long Creek Demonstration Area lies between 7,600 and8,800 ft (2317 and2683 m)elevation, which is the lower halfof the forested zone in the Wind River Drainage.The climate is cool and dry;moisture availability is the most limiting growth factor during the season. Soils are derived from sedimentary formations and glacial moraines derived from theWiggins formation. The clay content of the soils and seasonal distribution ofprecipitation make natural regeneration difficult on southerly and westerly aspects and flats,especially below 8,500 ft (2591m）. Cover types change with aspect and elevation;coniferous trees growonlyon favorable aspectsbelow 7,600 ft(2317 m),and seldom occur on more adverse aspects at higher elevations. Reestablishment ofconifers following fire is extremely slow on adverse aspects.Recovery from any drastic disturbance on this area can be expected to be slow unless seedlings are planted as the regeneration method.On some of the adverse aspects,the scattered limber pine (P.flexilis James)and lodgepole pine trees appear to be pioneers of a first generation forest. The lower part of the coniferous cover could be classed as Abies lasiocarpa-Arnica cordifolia habitat type,milk vetch phase.This habitat type on the Wind River District has almostno potential to be dominated by Abies lasiocarpa because the development of the climax community requiresmore time than is permitted by the natural fire cycle. Inland Douglas-fir(Pseudotsuga menziesii [Mirb.] Franco) predominates in an alternative seral community on this habitat type where soils are basic.At this elevation,the inland Douglas-fir/mountain snowberry habitat ispresent on soils derived from limestone formations. Aspen(Populus tremuloides Michx.)isa short-lived seral communityreplaced by limber pine orlodgepole pine in the first generation.Retention of aspen as a cover typerequires areduction in competition for moisture and cutting the live aspen tobreak the auxin flow so sprouting can occur. In most of the stands in thiszone,the lodgepolepine component of the stand is 150 to200 years old and dying out rapidly.Younger stands are still dominated by lodgepole pine andhave a manageable pole and smallsize sawtimber component.Thiszone of the coniferous forest isan Abieslasiocarpa-Vacciniumscoparium habitat type. Regeneration following disturbance is morerapid in thishabitat andwill tend tobemixed aged,withsome tolerant species seedlings and saplings present in the first50 years of stand development.Thenumber of mentprobablydependsonseedsource,oncethe lodgepole pine component accomplishes the necessary site modification.In some cases,competition by density stocked lodgepole pine may reduce spruce and fir regeneration. Site indexvalues forlodgepole pine are 30 to35ft(9.1 to 10.7 m) in 50years in the Abies lasiocarpa-Arnica cordifolia-milkvetchphase habitat,increasing to 45to50 ft (13.7 to 15.2m)in50 years in the Abies lasiocarpaVaccinium scoparium habitats. Throughout this area of the forest,basal area in natural standsfollows the site indexvalues,with basal areasaslowas65ft2/acre(14.4m²/ha)onthe lowersite index areas and increasing to 140 ft2/acre(31.1m²/ha)on the most productive sites.Total live conifer trees over 2 inches(5.08cm diameter atbreast height)(d.b.h.)on the 1,789acres(724ha) cruised rarely exceeded400per acre (988perha). The demonstration area contained approximately 1,898 acres(768 ha).Beforeharvesting,the area contained 3,777boardfeet(bd.ft.)ofgrossgreenvolume peracre and 1,664bd.ft.of dead standingvolumeperacre.Net volumeswere3,397bd.ft.ofgreenvolumeperacre and 1,332bd.ft.of deadvolumeperacre,or4729bd.ft.total net volume per acre. ## STAND PRESCRIPTIONS Three general prescriptions were applied:(1) cutting levels based on diameters,(2)leave-tree cuts,and(3) clearcuts.In each case,the primary purpose was to remove the foodsupply from thebeetle;thelarger diameter treesgenerallycontain the thickerphloem. However,other criteria were considered in each case. Eachprescriptionrequired retention ofadequate forest cover topromotenatural regeneration,wildlifeneeds, andvisual qualities,andwas designed to fit the conditionof thestand and its ecology topromote future development under natural conditions. The prescriptions and their applications were: - 1.Diameter cuts. - (1) Late transitional stands that had converted to the spruce-fir type.The lodgepole pine component was decadent or dying rapidly. In this case,adequate lodgepole pine growing stock was to be retained.Lodgepole pine regeneration could be expected to fill in openings created by logging. - a,Cut all lodgepole pine 7 inches (17.78 cm) d.b.h. and larger and salvage dead trees 8 inches (20.32 cm) d.b.h.and larger.This prescription was applied to three different stand conditions: - (2) Two-aged lodgepole pine stands that contained very few tolerant trees.The understory wasprimarily lodgepole pine, and the residual stand ofseedlings and saplings would be understocked.Trees less than 7 inches(17.78 cm)d.b.h.down to the seedling-sapling understory were not suitable growing stock because of disease-dwarf mistletoe (Arceuthobium americanum)and comandra blister rust (Cronartium comandrae). It was necessary on these sites to retain the undesirable pole timber to protect the site until natural regeneration occurs to bring the seedlingsapling stand up to 300 per acre (121 per ha).Timely removal of mistletoe-infected trees will be required. In some cases where stocking was inadequate and residual trees were sparse-less than 100 per acre(40 per ha)-planting wouid be necessary. Lodgepole pine or inland Douglas-fir containerized stock shouid be planted at200 to 400 treesperacre(81 to 162per ha) depending on the number and size of residual growing stock trees. - (3) Heavily stocked lodgepole pine pole timber stands where the age and disease conditions made regeneration of the stand desirable,and enough trees less than7 inches (17.78 cm) d.b.h.were present to furnish adequate cover to meet forest cover objectives,including site protection.Adequate natural regeneration was expected in these stands. 2. b.Cut all lodgepole pine trees 10 inches (25.40 cm） d.b.h.and larger and salvage all dead or at tacked trees8inches (20.32 cm) d.b.h.and larger.Thisprescription was applied to isolated stands in the unthinned component where forest cover was not maintained forproduction ofwood products,butprimarily where lodge pole pine was the principal component and cover objectives required retaining forest cover to protectother values. Site potential was low in these stands,eco systems were exceptionally fragile,and values other than timber were paramount.The prescription was applied to stands thatwere sparsely stocked and on adverse aspects.These stands were suspected to be first-generation coniferous forests,hence were fragile ecotones,and disruption could reverse ecologic trends.Subsequent treatments on regulated lands will be overstory removal in one or two steps,depend ing on disease conditions,regeneration success,and visual quality needs. - C. Cut all lodgepole pine trees 12 inches (30.48 cm) d.b.h.and larger and salvage all dead or attacked trees8 inches(20.32 cm) and larger.This prescription was applied to stands where lodgepole pine was the principal component,site potential was extremely low,stands were sparsely stocked,aspects were adverse,and stands contained trees exceeding this diameter limit. 2. 2.Leave-tree cuts. The leave-tree prescription was applied to two stands and required leaving 100 trees per acre (40 trees per ha),while removing the balance of the lodgepole pine component of the stand.All selected leave trees were the largest,most desirable lodgepole pine,growing stock,and sufficient desirable growing stock trees ofother species were retained to result in an average stock (17.78cm) d.b.h. Because of small islands of old lodgepole pine that escaped the fire that regenerated these two stands, and because these stands contained mistletoe infection centers,small clearcuts also were required. Natural regeneration could be expected in 5 years if these clearcuts did not exceed 5 acres (2 ha). - 3.Clearcuts. Six areas,averaging 14 acres (5.7 ha) each,were clearcut.These were in fire-regenerated pole timber stands.There were small islands of old-aged,larger diameter lodgepole pine trees thatwere diseased and decadent. Some of these islands had lodge pole pine andlor spruce-fir understories.Because of the heavy fuel accumulations in the pockets ofold growth,bulldozer piling and slash burning were desirable tomeet fuel managementobjectives. ## METHODS A total of 37 cutting units and one check block unit were laid out in the demonstration area: 10 units in the 7-inch (17.78-cm) cutting block - 17 units in the 10-inch (25.40-cm) cutting block - 2units in the 12-inch (30.48-cm) cutting block - 6units in the clearcut block - 2units in the 100-leave-tree cutting block - 1check block unit Harvesting began in January 1979 and was completed inFebruary 1981,well before the 1981beetle flight.A summary of the pretreatmentstand structure and proposed cuts is shown in table 1. A survey of the demonstration area was made in the spring of 1982 to determine tree loss to the mountain pine beetle.A 20-percent survey was conducted in22of the 38units: - 6 of 10 units in the 7-inch (17.78-cm) cutting block - 2of 2 units in the 12-inch (30.48-cm) cutting block - 11of 27 units in the 10-inch (25.40-cm)cutting block - 2of2units in the 100-leave-tree block - 1check block unit The 20-percent survey used a 1-chain-wide strip (20 m) every5chains(100 m) and recorded beetle-killed trees in 1979,1980,and1981,othercausesofdeath,and diameter. Tree growth data were collected during the loss surveys.Basal area and radial growth measurements were taken at 5-chain (100 m) intervals along the cruise strip,using a 10BAF gage.nfortunately,imilar data were not taken before the harvest for comparison. | | Treatment | Treatment | Treatment | Treatment | Treatment | |-----------------------------|-------------|-------------|-------------|----------------|-------------| | Stand structure and volumes | 7-inch | 10-inch | 12-inch | 100-leave-tree | Clearcut | | Acres | | | | | | | Total | 1,132.0 | 581.0 | 60.0 | 39.0 | 86.0 | | Mean | 113.2 | 34.2 | 30.0 | 19.5 | 14.3 | | Live lodgepolelacre | | | | | | | Total | 1,633.0 | 3,668.0 | 686.0 | 428.0 | 1,475.0 | | Mean | 163.3 | 215.7 | 343.0 | 214.0 | 245.8 | | <7-inch | 864.0 | 1,925.0 | 458.0 | 242.0 | 769.0 | | Mean | 86.4 | 113.2 | 229.0 | 121.0 | 128.2 | | >7-inch | 769.0 | 1,743.0 | 228.0 | 186.0 | 706.0 | | Mean | 76.9 | 102.5 | 114.0 | 93.0 | 117.7 | | >10-inch | 352.0 | 656.0 | 88.0 | 62.0 | 271.0 | | Mean | 35.2 | 38.6 | 44.0 | 31.0 | 45.2 | | >12-inch | 166.0 | 282.0 | 14.0 | 24.0 | 156.0 | | Mean | 16.6 | 16.6 | 7.0 | 12.0 | 26.0 | | Live species/acre | | | | | | | Subalpine fir and other | 768.0 | 699.0 | 66.0 | 30.0 | 1,006.0 | | Mean | 76.8 | 41.1 | 33.0 | 15.0 | 167.7 | | Engelmann spruce | 194.0 | 47.2 | 0 | 2.4 | 248.0 | | Mean | 19.4 | 2.8 | 0 | 1.2 | 41.3 | | Aspen | 1,683.0 | 232.0 | 0 | 64.0 | 34.0 | | Mean | 168.3 | 13.6 | 0 | 32.0 | 5.7 | | Proposed cut | | | | | | | TIA | 769.0 | 656.0 | 14.0 | 228.0 | 1,475.0 | | Mean | 76.9 | 38.6 | 7.0 | 114.0 | 245.8 | | Gross volumelacre | | | | | | | Live cut | 4,468.0 | 3,518.0 | 3,683.0 | 3,205.0 | 4,093.0 | | Mean | 4,468.0 | 3,518.0 | 3,683.0 | 3,205.0 | 4,093.0 | | Salvage cut | 2,290.0 | 1,480.0 | 1,583.0 | 1,231.0 | 2,337.0 | | Mean | 2,290.0 | 1,480.0 | 1,583.0 | 1,231.0 | 2,337.0 | | Gross volume (M) | | | | | | | Green | 5,058.0 | 2,044.0 | 221.0 | 125.0 | 352.0 | | Mean | 505.8 | 120.2 | 110.5 | 62.5 | 58.7 | | Dead(≥8") | 2,592.0 | 860.0 | 95.0 | 48.0 | 201.0 | | Mean | 259.2 | 50.6 | 47.5 | 24.0 | 33.5 | | Uncut per acre | | | | | | | Lodgepole pine（≥2") | 891.0 | 2,916.0 | 558.0 | 39.0 | 877.0 | | Mean | 89.1 | 171.5 | 279.0 | 19.5 | 146.2 | | Total trees(≥2") | 1,602.0 | 3,661.0 | 624.0 | 43.0 | 2,132.0 | | Mean | 160.2 | 215.4 | 312.0 | 21.5 | 355.3 | | Average gross volume | | | | | | | per acre (M) | | | | | | | Green | 4.468 | 3.518 | 3.683 | 3.205 | 4.093 | | Dead | 2.290 | 1.480 | 1.583 | 1.231 | 2.337 | | Average net volume | | | | | | | per acre(M) | | | | | | | Green | 4.023 | 3.166 | 3.315 | 2.885 | 3.684 | | Dead | 1.832 | 1.184 | 1.267 | .985 | 1.870 | | Totaladjustednetvolume | | | | | | | Volume per acre | 5.855 | 4.350 | 4.582 | 3.870 | 5.554 | | Netvolume | 6.628 | 2.528 | .275 | .151 | 478 | ## RESULTS The stand structure changed proportionally to the intensity of harvest cut used in each block (table 2).Stand average diameter (d.b.h.) changes were: | Treatment | Original diameter | Original diameter | Diameter after harvest | Diameter after harvest | |-----------------------|---------------------|---------------------|--------------------------|--------------------------| | | Inches | cm | Inches | cm | | 7-inch(17.78-cm) cut | 7.8 | 19.81 | 7.0 | 17.78 | | 10-inch(25.40-cm)cut | 7.7 | 19.56 | 7.0 | 17.78 | | 12-inch（30.48-cm)cut | 7.4 | 18.80 | 7.3 | 18.54 | | 100-leave-tree cut | 7.5 | 19.05 | 8.0 | 20.32 | Table 2.-Stand structure before and after cutting | | Live lodgepole pine per acre by diameter class | Live lodgepole pine per acre by diameter class | Live lodgepole pine per acre by diameter class | Live lodgepole pine per acre by diameter class | Live lodgepole pine per acre by diameter class | Live lodgepole pine per acre by diameter class | Live lodgepole pine per acre by diameter class | Live lodgepole pine per acre by diameter class | Live lodgepole pine per acre by diameter class | Live lodgepole pine per acre by diameter class | Live lodgepole pine per acre by diameter class | |--------------------|--------------------------------------------------|--------------------------------------------------|--------------------------------------------------|--------------------------------------------------|--------------------------------------------------|--------------------------------------------------|--------------------------------------------------|--------------------------------------------------|--------------------------------------------------|--------------------------------------------------|--------------------------------------------------| | Treatment | Before cut | Before cut | Before cut | Before cut | Before cut | Trees acre | After cut | After cut | After cut | After cut | After cut | | | Total | <7 inches | 7-9 inches | 10-11 inches | >12 inches | cut per | Total | <7 inches | 7-9 inches | 10-11 inches | >12 inches | | 7-inch cut | 163.3 | 86.4 | 41.7 | 18.6 | 16.6 | 76.9 | 86.4 | 86.4 | 0 | 0 | 0 | | 10-inch cut | 215.7 | 113.2 | 63.9 | 22.0 | 16.6 | 38.6 | 177.1 | 113.2 | 63.9 | 0 | 0 | | 12-inch cut | 343.0 | 229.0 | 70.0 | 37.0 | 7.0 | 7.0 | 336.0 | 229.0 | 70.0 | 37.0 | 0 | | 100-leave-tree cut | 214.0 | 121.0 | 62.0 | 19.0 | 12.0 | 114.0 | 100.0 | 一 | 一 | 一 | 一 | | Clearcut | 245.8 | 128.2 | 72.5 | 19.2 | 26.0 | 245.0 | 0 | 0 | 9 | 0 | 0 | | Check area | 251.0 | 255.0 | 196.0 | 91.0 | 42.0 | 0 | 251.0 | 255.0 | 196.0 | 91.0 | 42 | 'Data not available on distribution. Include only 4-to 6-inch trees. Considering only the kill by the mountain pine beetle, the trend for the3years(2yearsbefore the cutwascompleted and 1yearafter completed cuts) israther dramatic(table 3 and fig.1). In all cutting blocks,the numberof trees infested dropped considerably after harvesting; the check block continued to lose trees to thebeetle at about the samerate. It is evident thattreelosstosecondaryinsects,such asIps,Pityophthorus,Pityogenes,and Pityokteines,and comandra rustlessened after treatment(table 4).However,this apparentreductionoflossmaybe anartificial effectofsampling,because the checkareas also showed noloss due tothese factorsin 1981 (theyear after cutting was completed). Table3.-Tree mortality due to the mountainpine beetle | | Number of trees killed per acre | Number of trees killed per acre | Number of trees killed per acre | Number of trees killed per acre | |--------------------|-----------------------------------|-----------------------------------|-----------------------------------|-----------------------------------| | Treatment | 1979 | 1980 | | 1981 | | 7-inch cut | 0.72 | 0.51 | | 0.09 | | 10-inch cut | 35 | .66 | | .07 | | 12-inch cut | .19 | 5.00 | | 1.15 | | 100-leave-tree cut | .20 | .10 | | 0 | | Check area | 2.53 | 5.77 | cut completed | 4.23 | Figure 1.-Tree loss due to the mountain beetle within the demonstration areas. Table 4.-Trees killed per acre by cutting block,year,cause,and diameter | Treat. ment | Year of kill | Cause of death | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Diameter of tree killed (inches) | Total | | | |------------------------|------------------------------------|-----------------------------------------------------------------------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|--------------|-------------------------------------|--------------------------------------------------| | Treat. ment | Year of kill | Cause of death | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | >17 | trees killed | Trees killed per acre | Trees killed per acre | | 7-inch | 1979 | MPB | 2 | 3 | 3 | 3 | 7 | 4 | | 1 | | | | | 24 | 0.72 | 0.72 | | cut | | Pity's? Total | 1 | | 1 | 1 | | | | | | | | | 3 | .09 | .09 | | | | MPB | | 3 | 3 | 4 | 4 | 7 | 4 | 1 | 1 | | | | 27 | .81 | .81 | | | 1980 | Pity's | | 2 | 3 1 | 5 1 | 1 | 2 | 3 | 1 | | | | | 17 | .51 .06 | .51 .06 | | | | Comandra | 1 | | | | 1 | | 3 | 1 | | | | | 2 1 | .03 | .03 | | | | Total MPB | 1 | 2 | 4 | 6 | | 2 | | 1 | | | | | 20 | .60 | .60 | | | 1981 | | | | | | | | | | | | 1 | | 3 | .09 | .09 | | | All years | Total | | | | | 8 | 6 | 4 | 1 | | | 1 | 1 | 3 50 | .09 | .09 | | | | | 4 | 5 | 8 | 10 | | | | 3 | | | 1 | 1 | | 1.51 | 1.51 | | 10-inch | 1979 | MPB | 1 | 2 | 2 | 10 | | | | | | | | | 21 | .35 | .35 | | cut | | Ips spp. | 1 | 3 | 2 | | 2 | 2 | | | | | | | 6 | .10 | .10 | | | | | 6 | | | | | | | | | | | | | | | | | | Pity's | | 8 | 3 1 | 5 | 2 | 2 | | | | | | | 22 | .36 .03 | .36 .03 | | | 1980 | Comandra Total | 8 | 1 15 | 6 12 | 15 9 | 4 | 3 | | | | | | | 2 51 | .84 .66 | .84 .66 | | | | MPB Pity's Comandra | 1 4 | 6 3 | 4 2 | 1 | | | 2 | | | | | | 40 12 | .20 .08 | .20 .08 | | | | | | 2 | | 1 11 | 4 | 3 | 2 | | | | | | 5 57 | .94 | .94 | | | 1981 | Total MPB | 5 | 11 | 18 1 | 1 | 1 | | | | | | | | 4 | .07 | .07 | | | | | | | 1 | 1 | 1 | | | | | | 1 | | 4 | .07 | .07 | | | All years | Total | | | | 27 | 7 | | | | | | 1 | | 112 | 1.78 | 1.78 | | 12-inch | | MPB | 13 | 26 | 28 | | | 5 | | | | | 1 | | | | | | cut 100-leave tree cut | 1979 1980 1981 All years 1979 1980 | Comandra Total MPB Pity's Comandra Total MPB Total MPB Ips spp. Total MPB MPB Pity's Comandra | 2 2 1 1 3 1 1 2 1 1 4 | 1 1 2 1 1 3 1 | 1 1 4 4 2 | 5 5 5 | 1 1 5 1 6 14 1 | 10 18 18 | 2 3 3 | | | 7 3 1 | 1 1 | | 1 | .19 4 .77 1 .96 1 28 6 6 39 2 3 5 1 | 5.00 .19 .19 5.38 1.15 1.15 7.50 .20 .30 .50 .10 | | Check area | 1980 | Ips spp. Total Total | 1 1 | 1 2 4 3 4 1 | 2 7 | | 7 | 7 3 | 3 | | 6 | | | | 5 26 1 | 2 3 | .20 .30 | | | 1981 All years 1979 | MPB Total MPB MPB | | 2 1 | 1 7 | 1 1 9 | 5 | | 1 10 | 8 | 1 | 9 | 5 2 | | | 1 1 6 36 | .10 .10 06 2.53 | | | 1981 | | | | | | | | | | | | | 1 | | | | | | | | | | | 5 | 9 | | | | | | | | | | | | | | | | | 4 | | | | | | | | | | | | | | | | | | | 6 | 12 | | | | | | 1 | | 6 | | | | | | | Total | | | | | | | | | 5 | | 2 | | | | | | | | Pity's Total | | | 3 4 | 9 11 1 | 5 15 | | 1 10 | | 1 6 | 9 1 | 5 8 | 6 | 1 84 | 3 39 1 .07 .07 5.91 | .21 2.74 5.77 | | | | | | | | | | | 13 | | | | | | 60 | 4.23 | 4.23 | | | | | | | | | | 11 | | 6 | | | | | | | | | | | | | | | | | | | | | | 4 | | | | | | | | | | | 6 | | 9 | 11 | | 6 | | | | | | | | | | | | | | | 5 | | | 13 | | 5 | | | | | 4.23 | 4.23 | | | | | | | | 26 | | | | | | | 4 | | 60 | | | | | | | | 5 | | | | | | | | | | | | | | | | | | | | | | | 29 | 24 | 19 | | | | 1 7 | 82 1 | | | | | | | | | | | | 38 | | | | | | | | | | | | | | | | | | | | | | | 2 | | | | | | | | | | | | | | | | | | | | | | 183 | | | | | | | | | | | | | | | | | | | 13 | | | | | | | | | | | | | | | | | | | | 12.88 | 12.88 | | | | | | | | | | | | | | | 6 | | | | | | | All years | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12 | | | | | | | Adding the loss due to themountainpinebeetle, secondary insects,and comandra rust to the trees cut peracre gives the gross numberof trees removed and thus the residual trees per acre (table 5).All cutting blocksnowcontain almost the same numberof treesper acre,which is aboutone-half thenumberperacre now in the check area,although the average stand diameteris different. Residual basal areafollowed the level ofcutaswould be expected (fig.2).Using the check blocks as a base, then66percentof thebasal areawasremovedin the 7-inch(17.78-cm)blocks;55percent in the 10-inch (25.40-cm)blocks;45percent in the 12-inch (30.48-cm) blocks;and 63 percent in the 100-leave-tree blocks. Therewas an apparent andslightlygreaterradial growth,of thoseresidual treesmeasured,in the 12-inch (30.48-cm),100-leave-tree,and checkblocksas compared to the7-inch(17.78-cm)and 10-inch(25.40-cm)blocks (fig.3).This does not necessarily reflect release by cutting,becauseonly1to2yearsofgrowthoccurredsince cuttingwas started. Table 5.-Net effects to the stands from cutting levels and mortality factors | | Trees per acre | Trees per acre | Trees per acre | Trees per acre | Trees per acre | Trees per acre | | |---------------------|------------------|------------------|------------------|------------------|------------------|------------------|----------| | Treatment | | | Before Number | Before Number | Before Number | Before Number | Residual | | | cut | cut | MPB1 | Ips spp. | Pity's? | Comandra | | | 7-inch cut | 163.3 | 76.9 | 1.32 | 0 | 0.15 | 0.03 | 84.90 | | 10-inch cut | 215.7 | 113.2 | 11.08 | 0.10 | 56 | .11 | 90.76 | | 12-inch cut | 343.0 | 229.0 | 6.34 | 0 | .19 | .96 | 88.66 | | 100-leave- tree cut | 214.0 | 114.0 | .30 | .60 | 50 | 0 | 99.70 | | Check area | 196.0 | 0 | 12.53 | 0 | .28 | .07 | 183.12 | MPB=Mountain pine beetle. Pityophthorus,Pityogenes,and Pityokteines. Figure 3.-Average radial growth of stand per year for last 10 years by cutting block. Figure 2.-Residual basal area of cutting blocks. ## DISCUSSION Having seen theimmediate results of the cutting levels,thequestionnowisof thefutureof thesestands, withrespect to the activityof thebeetle andstand development.The harvest levelsreduced the current levelof losssomewhatproportionally,butwill thebeetle resumekilling trees at the sameratio as before treatmentor has a change been induced in the course of the infestation?Toproject an answer to thisquestion,these mortality trend datawereused intheRateof LossModel (Cole and McGregor,inpress)topredict the rateof future tree loss and numberofyearsofsuch an infestation (fig.4). Figure 4.-Predicted trees per acre killed by mountain pine beetle, postharvest by cutting levels. Thisprojection showed that theinfestation within the check area shouldpeakin1981,with46.9 treeskilledper acre(19 perha),and subside to 1.1 trees peracre (0.44 per ha)by 1989,tailing to 0.02 tree per acre (0.008per ha) by 1993.The diameter-limit cutsreduced thepeakloss ratherproportionally to the extentof cutting;forexample,peakkill wasgreaterin the12-inch(30.48-cm)cuts than in the 7-inch(17.78-cm) cuts.The expected length of infestation changed accordingly,with the longest period ofoutbreakexpected forthe7-inch(17.78-cm) cut.The exceptionwas the 100-leave-tree cut.Thiscut extended thepredictedlifeof theinfestation to theyear2012,with peaktreelossofonly 1.5 treesperacre(0.61perha)in theyear 1993(table 6). Table 6.-Predicted peak loss,length of infestation,and annual drain from the mountain pine beetle by cutting level (trees per acre) | Treatment | Peak loss | Peak year | Years of infestation | Total loss | Annual drain | |---------------------|-------------|-------------|------------------------|--------------|----------------| | Check area | 46.9 | 1981 | 14 | 180.5 | 12.9 | | 12-inch cut | 22.1 | 1981 | 18 | 80.1 | 4.4 | | 10-inch cut | 10.3 | 1982 | 26 | 62.5 | 2.4 | | 7-inchcut | 12.3 | 1982 | 13 | 32.8 | 2.5 | | 100-leave- tree cut | 1.5 | 1993 | 33 | 23.6 | .7 | The 100-leave-tree cut,according to these predictions, wouldreduce tree lossfrom the mountain pinebeetle to a low amount.This cut would also be advantageous in reducing orminimizing dwarf mistletoe occurrence (Wicker 1967;WickerandShaw 1967).Once the area is reseeded and theregeneration heightexceeds snow depth,theleave treesshouldberemoved.Thesmall targetarea of theregeneration,thewashing action of the snow inremoving dwarf mistletoeseeds,and theyoung stand being immune to themountain pine beetlemay well be thekeys toproducing a healthynewstandof lodgepole pine. ## SUMMARY The demonstrationarea on which diameter-limit and leave-tree cutswere applied toreduceor minimize lodgepolepine losses to the mountainpinebeetlewas evaluated the firstyear aftercutting.First-year losses werereducedproportionally to the intensityofcut.Projected losses and continuation of the mountain pine beetleinfestationwerederived from thepredictiveRate of LossModel.Thebestdeterrent of recurring infesta tion-amountoflosses andlengthoftime-wasthe 100-leave-tree cut.The 100-leave-tree cut alsowas the best in encouraging regeneration and reducing dwarf mistletoe infection. ## PUBLICATIONS CITED Cahill,Donn B.Cutting strategies as control measures of themountainpine beetle in lodgepolepine in Colorado.In:Berryman,Alan A.;Amman,Gene D.:Stark, Ronald W.,tech.eds.Theory and practice of mountain pine beetlemanagement in lodgepolepine forests: symposium proceedings;1978April 25-27;Pullman, WA.Moscow,D:niversityofdaho,Forest,Wildlif and Range Experiment Station;1978:188-191. Cole,WalterE.McGregor,MarkD.Estimating therat and amount of treeloss from a mountain pine beetle infestation.Inpress. Cole,Walter E.;Cahill,Donn B.Cutting strategies can reduceprobabilitiesofmountainpinebeetle epidemics inlodgepolepine.J.For.74:294-297;1976. McGregor,MarkDCole,Walter E.Harvesting strat egiesformanagementofmountainpinebeetle infestations in lodgepole pine.In press. Wicker,Ed F.Seed destiny asaklendusicfactorof infection and itsimpactuponpropagation of Arceuthobium spp.Phytopathology.57(11):1164-1168; 1967. Wicker,Ed F;Shaw,C.Gardner.Targetarea asa klendusicfactorin dwarfmistletoe infections. Phytopathology.57(11):1161-1163;1967. The Intermountain Station,headquartered in Ogden,Utah,is one of eightregional experiment stations charged withproviding scientific knowledge to help resource managers meet human needs and protect forest and range ecosystems. Field programs and research work units of the Station are maintained in: The Intermountain Station includes the States of Montana, Idaho, Utah,Nevada, and western Wyoming.About 231 million acres,or 85 percent,of the land area in the Station territory are classified as forest and rangeland. These lands include grasslands,deserts,shrublands,alpine areas,and well-stocked forests. They supply fiber for forest industries; minerals for energy and industrial development;and water for domestic and industrial consumption.They also provide recreation opportunities for millions ofvisitors each year. Boise,Idaho Bozeman, Montana (in cooperation with Montana State University) Logan, Utah (in cooperation with Utah State University) Missoula, Montana (in cooperation with the University ofMontana) Moscow,ldaho (in cooperation with the University of Idaho) Provo,Utah (in cooperation with Brigham Young University) Reno, Nevada (in cooperation with the University of Nevada)