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ABSTRACTThis summary of forest health conditions across British Columbia (BC) in 2002 is a compilation of the an-nual provincial aerial overview surveys, insect population predictions, information on forest health agentsnot aerially detectable and special project information. Ministry of Forests forest health specialists and foresthealth consultants supplied this information.
The largest mountain pine beetle epidemic in recorded history in BC continued to expand, with attackedarea more than doubled over 2001 to just under two million hectares. The largest increase occurred in thePrince George Forest Region, where 685,598 ha were affected, followed closely by 539,315 ha in the CaribooForest Region and 511,798 ha in the Prince Rupert Forest Region. Mountain pine beetle attack was lower inthe southern forest regions (Vancouver, Kamloops and Nelson) but they still experienced significant rises ininfested hectares. A series of mild winters and an abundance of mature lodgepole pine have contributed tothe current outbreak situation. Despite aggressive control tactics, a further population expansion is expectednext year if the winter weather continues to be mild.
Western balsam bark beetle and spruce beetle were two other bark beetles identified as a concern. Thewestern balsam bark beetle attacked nearly one million hectares of sub-alpine fir stands throughout BC(particularly in the northern forest regions). The area affected by spruce beetle increased more than 2 ½times over 2001 levels to a total of 268,995 ha, of which 94% occurred in the Prince George Forest Region.
Defoliators also had significant impact on the health of forests in BC. Western spruce budworm continuedon an upward trend, defoliating a total of 487,443 ha of Douglas-fir, primarily in the Cariboo and KamloopsForest Regions. Significant defoliation is also predicted for next year. Defoliation by the 2-year budwormaffected 160,231 ha of true fir and spruce stands in the Prince George, Cariboo and Kamloops Forest Regions.The eastern spruce budworm, a chronic defoliator of true fir and spruce, continued to damage stands in thePrince George Forest Region (although aerial mapping did not occur in 2002). Western hemlock looper waspredominantly in the second year of a predicted four year cycle in the southern portion of the province. In2002, the western hemlock looper defoliated 44,277 ha. Further increases in size and severity are predictedfor next year. Provincially, almost 68,000 ha of deciduous stands were also attacked by various defoliators.
Pine needle diseases affected large areas of lodgepole pine, particularly in the central and northern portionsof the province. Pine needle cast infected 265,930 ha in the Cariboo Forest Region. Low level aerial surveysdetected unprecedented levels of Dothistroma needle blight in the Prince Rupert Forest Region, with 19,530ha affected.
Aspen and poplar leaf and twig blight infected aspen (and some cottonwood) stands throughout the PrinceRupert and Prince George Forest Regions. The affected hectares more than tripled to 80,156 ha this year.Various other forest health factors such as false Hemlock looper, Douglas-fir beetle, flooding, bear andporcupine damage caused localized damage in different areas throughout the province.
2002 SUMMARY OFFOREST HEALTHCONDITIONS IN
BRITISH COLUMBIA Douglas-fir beetle
INTRODUCTION
Table 1. Number of flying hoursrequired by each Region tocomplete the 2002 provincialaerial overview surveys.
The B.C. Ministry of Forests(BCMOF) is responsible fordetecting, recording and monitor-ing insects, diseases, animaldamage and environmentalfactors in the forests of BritishColumbia (BC). Much of this
information is gathered at theregional level (Figure 1) throughaerial overview surveys. Experi-enced personnel map foresthealth disturbances from fixed
wing aircraft. The map scale isusually 1:100,000, which allows forefficient coverage of the provinceat an acceptable level of accuracy.The standards employed foroverview surveys have beenadopted from the Canadian Forest
Service standards. Details of thesurvey methodology are availableonline at the Resources Informa-tion Standards Committee website:http://srmwww.gov.bc.ca/risc/
pubs/teveg/foresthealth/index.htm.
2002 marks the fourth year thatthe BCMOF has conductedprovincial aerial overviewsurveys. Methodology of data
collection varied from region toregion over the first three years,consisting of a mosaic of over-view and detailed aerial surveydata (collected specifically fordirecting bark beetle manage-ment activities). In 2002, all
Preparing for an aerial overview survey
Region Flight hours
Vancouver 52.5
Cariboo 240.8
Kamloops 48.0
Prince Rupert 177.5
Prince George 100.8
Nelson 96.7
Total 716.3
3
Figure 1. Map of British Columbia outlining Ministry of Forests Regional and District boundaries in 2002.
4
Disturbance Intensity Class Description
Mortality Light 1-10% of the trees in the polygon recently killed.
Moderate 11-29% of the trees in the polygon recently killed.
Severe 30%+ of the trees in the polygon recently killed.
Defoliation Light Some branch tip and upper crown defoliation, barely visible from the air.
Moderate Noticeably thin foliage, top third of many trees severely defoliated, some completely stripped.
Severe Bare branch tips and completely defoliated tops, most trees sustaining more than 50% total defoliation.
Table 2. Intensity classes used for recording forest health damage.
data collected for the overviewsurvey conformed to the currentmethodology, which created aconsistent, cohesive picture offorest disturbances throughoutBritish Columbia.
The 2002 provincial aerial over-view surveys were conducted frommid July through the first week ofSeptember. The surveys werecompleted three weeks earlierthan in 2001 due to favourableweather conditions and betterproject organization. A total of716.3 flying hours were requiredto survey the province (Table 1).
The majority of all forested landswere surveyed; the main excep-tion was Fort Nelson and thenorthern portion of Fort St. JohnForest Districts, where easternspruce budworm was the primaryforest health agent. The windowof opportunity for mapping thisdefoliator occurred before the
aerial survey contract wasawarded and heavy rains in Julywashed away most of the sympto-matic red foliage from the defoli-ated trees. Consequently, theareas with budworm damagewere not flown in 2002.
Forest health disturbances thatkill trees (such as beetles,flooding, windthrow, porcupine,etc.) were detected during aerialsurveys by observing foliagecolour changes in dead trees.Only recently discoloured trees(attacked and killed within thelast year) were mapped; thereforeeach year's survey results do notinclude trees that have been deadfor more than one year. Smallinfestations of up to 50 trees wererecorded as spot infestations.Larger infestations were drawn as
polygons on the survey map, withthe percentage of recently killedtrees separated into three intensityclasses (Table 2).
Visible defoliation caused byinsects and foliage diseases wasalso recorded during the surveys.Defoliator damage tended to bewidespread throughout areas,and was therefore mapped only asinfested polygons, not spots. Onlycurrent defoliator damage wasrecorded, which was assessed as aportion of the tree defoliated(average for the polygon), ratherthan a percentage of treesattacked within a polygon (Table2).
Sketch mapped forest healthdisturbances were digitized usingBCMOF Forest Practices Branchstandards, available on theMinistry of Forests website (http://www.for.gov.bc.ca/hfp/forsite/overview.htm).
Certain forest health concerns,particularly diseases such as rusts,cankers, decays and dwarfmistletoes, are not usually visibleduring aerial overview surveys.Therefore, these disturbances areonly covered in this report whenidentified by other survey meanssuch as ground surveys or specialproject surveys. This report is asummary of the 2002 aerialoverview survey results, withadditional insect populationpredictions and special projectsinformation supplied by regionaland district forest healthspecialists and consultants.
Mountain pine beetle continued tobe the most damaging agent inthe province in 2002, with overdouble the infested hectaresrecorded in 2001. Other
5
Table 3. Summary of hectares affected by forest damaging agents as detected in 2002 aerial overview surveys in British Columbia.
a Includes infestations in parks totalling 482,426 ha.b Does not include unmapped eastern spruce budworm (estimate 1.6 million ha).c Does not include all large wildfires mapped by Protection Branch.d Does not include areas recorded in low elevation surveys (additional 18,365 ha).
0
500,000
1,000,000
1,500,000
2,000,000
2,500,000
3,000,000
3,500,000
Hect
ares
Affe
cted
1999 2000 2001 2002
Year
Bark beet les
Defoliators
Figure 2. Hectares affected by major bark beetles and defoliators in BC.
significant damaging agentsincluded: western balsam barkbeetle, western spruce budworm,spruce beetle, two-year cyclebudworm, eastern sprucebudworm, western hemlocklooper, pine needle diseases, satinmoth, and aspen/poplar leaf andtwig blight. Several other foresthealth agents caused localizeddamage (Table 3).
Overall, bark beetles anddefoliators were the most visibleforest health factors to affect theforests of BC over the last fouryears. Bark beetle activitycontinued to increase signifi-cantly, due to mild winters andlow beetle mortality rates.Defoliator populations tend tofluctuate widely over a relativelyshort time period. The totalhectares defoliated in 2002 aremissing an estimated 1.6 millionhectares of unmapped easternspruce budworm defoliation(Figure 2).
A Provincial Forest HealthStrategy is being developed andwill be completed in early 2003.This strategy will provide overallobjectives and actions to achieveforest health goals and help toidentify provincial priorities.These provincial goals andpriorities will guide ministry andindustry operations and researchover the next few years.
The following pages reportdetailed observations of pestdamage as noted during 2002.
Damaging Agent Hectares Affected Major Bark Beetles:
Mountain pine beetlea 1,968,641 Western balsam bark beetle 990,515 Spruce beetle 268,995 Douglas-fir beetle 9,078 Lodgepole pine beetle 1,301
Defoliators: b Western spruce budworm 487,352 2-year budworm 160,231 Satin moth 45,394 Western hemlock looper 44,277 False Hemlock Looper 4,074 Forest tent caterpillar 4,127 Birch leaf miner 18,184 Unspecified/misc. defoliator 6,908
Abiotics: Wildfirec 5,179 Flooding 4,902 Windthrow 460 Slide 479
Other: Pine needle cast 268,314 Aspen/poplar leaf/twig blight 80,156 Porcupine 6,244 Dothistromad 1,165 Larch needle blight 868 Bear 796 Miscellaneous 727
Provincial Total 4,378,367
6
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
Hect
ares
Affe
cted
Nelson Kamloops Vancouver Cariboo Prince Rupert PrinceGeorge
Region
2000
2001
2002
DAMAGING AGENTS OF PINEMountain Pine Beetle, Dendroctonus ponderosae
The mountain pine beetle is themost destructive pest of maturepines in British Columbia, andcontinues to be the largest threatto BC forests in terms of timberloss, environmental concerns andnegative economic impacts.Infestations are causing extensivetree mortality throughout theprovince, from sea level up to theelevational limits of pine.
The most extensive mountain pinebeetle epidemic in recordedhistory is presently underway inBritish Columbia (Figure 4).Beetle populations have been onthe rise for several years, due toan abundance of maturelodgepole pine and veryfavourable weather conditions. It
Figure 3. Change in hectares affected by mountain pine beetle from 2000 – 2002 in the sixprovincial forest regions.
is believed that the province-widedrought in the summer of 1998contributed to the increase ofmountain pine beetle. Droughtstressed trees were then less ableto resist mass attack by mountainpine beetle. Beetle populationswere further bolstered by a seriesof mild winters. Without the usualprolonged cold periods in thewinter, beetle larval mortality hasbeen very low. This hascontributed further to the currentmountain pine beetle outbreak.
Hectares under attack by themountain pine beetle in BC haveincreased twelve fold from164,567 ha in 1999 to 1,968,641ha in 2002. Attack in all regionsexcept Kamloops and Nelson has
at least quadrupled from 2000 to2002 (Figure 3). Of the standsaffected by mountain pine beetlein 2002, 30% sustained severemortality (up 7% over 2001), 25%moderate, and 45% lightmortality.
Prince George Forest Regionexperienced the greatest increaseand consequently the largestaffected area in BC at a total of685,598 ha. The majority of theattack was recorded in theVanderhoof, Prince George andFort St. James Forest Districts at66%, 21% and 10% of the regionaltotal, respectively. VanderhoofForest District, particularly in thesouthwest, sustained the greatestincrease in attacked hectares with
7
Figure 4. Mountain pine beetle infestations recorded in British Columbia in 2002.
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Forest Health Ae rial Overview 20 02Forest Health Ae rial Overview 20 02Forest Health Ae rial Overview 20 02Forest Health Ae rial Overview 20 02
info@gisol utions.ca(250 ) 8 81-7727
Projection: Albers Equal AreaBase: 1:6,000,000 TRIMDate: January 20, 2003
40 0 40 80 120 16020Kilometers
1:8,500,000Scale:
Polygonal Data
Spot Data
Mountain Pine Beetle
Mountain Pine Beetle
Highw ay
Railw ay
International Boundary
Interprovincial Boundary
River
Lake
Island
Coast
Base Data
Road
Fores t Region Boundaries
8
Mountain pine beetle infestation in Tweedsmuir Park
'salt and pepper' spotting wasdeveloping along the edge of thebeetle infestation in the Big Lakeand Gaspard BMUs. ChilcotinForest District had the largestproportional increase of twenty-nine fold to 34,519 ha, primarilyin the Dean River corridor. Thisexpansion was due predomi-nantly to beetle pressure fromTweedsmuir Provincial Park andVanderhoof Forest District, andsome from Quesnel Forest District.
Hectares affected in the PrinceRupert Forest Region in 2002 werejust under the total for the CaribooForest Region at 511,798 ha.Almost all of the attack waslocated in Lakes Forest Districtwith 498,057 ha infested, of which235,707 ha (about half of totalinfested area) were in TweedsmuirProvincial Park and the portion ofthe Entiako protected area withinthe Lakes Timber Supply Area(TSA). Infestations in Morice andBulkley Forest Districts actuallydecreased significantly this year.
Due to the large volume of attackin the Lakes Forest District, it wasnecessary to move large quantitiesof infested timber into the BulkleyForest District for milling this year.To accomplish this without furtherspread of the beetle from theinfested timber, the mills (particu-larly Pacific Inland Resources) inconsultation with RegionalEntomologist Ken White, devised avery detailed transportation and
storage plan.Weather stationswere closelymonitored todetermine tem-perature thresh-olds for possiblebeetle flights.Hauling planswere devised toaccommodate thethresholds,including nighthauling whentemperatures werelow enough and
emergency plans fortimber pick-up in case of
truck breakdowns. Beetle emer-gence within mill yards wascontrolled by a variety of trapsand sprinkler systems.
Mountain pine beetle attack alsocontinued to rise in the VancouverForest Region with a 50% increasefrom 2001 to a total of 174,171 haaffected (Figure 3). Most of the
from high valueareas. Pendingfunding, thisproject could beunderway in thespring of 2003.
Mountain pinebeetle popula-tions in theCariboo ForestRegion also increasedat unprecedented rates,from 103,792 ha in 2001 to539,315 ha in 2002 (Figure 4).Almost 70% of the affected hec-tares were located in the QuesnelForest District, with the largestexpansion west of the Fraser Riverin the Kluskus, Pan and EligukBeetle Management Units(BMUs). All districts experienceda rise in attack; Williams LakeForest District was second with105,904 ha affected, particularlyin the Riske, Mackin, HawksCreek, Big Lake, Meldrum andWilliams Lake BMUs. Scattered
a rise from 77,944 ha in 2001 to450,904 ha in 2002. Roughly56,000 ha of the infested area inthe Vanderhoof Forest District arein Entiako Provincial Park. In FortSt. James and Vanderhoof ForestDistricts, lodgepole pine beetlehas been observed in the base ofsome mountain pine beetleattacked trees. To protect theurban environment in PrinceGeorge, a local forestry consultingfirm is coordinating a researchproposal to useanti-aggregationcompounds torepel the moun-tain pine beetle
mortality continued to occur inthe Mid-Coast Forest District(166,959 ha), with 153,063 halocated in Tweedsmuir ProvincialPark. Increases also took place in
9
Lodgepole pine killed by mountain
pine beetle in the Chilcotin
the Dean River drainage,spreading westward fromTweedsmuir Provincial Park to thePacific Ocean. Additional areas ofsignificant beetle infestations werein the Whistler-Pemberton corri-dor, on the east side of LillooetLake and in Manning ProvincialPark. Control activities have beeninitiated to the north of Whistlerin an attempt to prevent thesouthward spread of the beetle.
Kamloops Forest Region continuedto be less affected by mountainpine beetle than most otherregions. Affected hectares contin-ued to rise however, particularlyin the northern portion of theKamloops Forest District. Modestdeclines occurred in Merritt andSalmon Arm Forest Districts. Intotal, 35,903 ha were attacked inthe Kamloops Forest Region.
Nelson Forest Region continued tobe the least affected of all regions,though infestation levels morethan doubled from 9,611 ha in2001 to 21,856 ha in 2002. Thelargest increase and the majorityof attack occurred in theCranbrook Forest District with7,785 ha affected, up from only593 ha in 2001. Most of thisattack was located along the ElkRiver from Fernie to Elkford.Invermere and Arrow ForestDistricts also contained significantproportions of the region's attackat 22% and 17%, respectively.
The increase of mountain pinebeetle attack across the provincereflects a healthy beetlepopulation. In general, large
infestations from 2001 showed analarming amount of dispersal in2002 in the form of numeroussmall patches found outside of themain attack area in previouslyuninfected stands. This includedpatches of current attack only (noold attack nearby) in many areas.
Weather plays a significant role inthe timing of beetle flight, beetledevelopment, and the ability oftrees to resist attack.
Province wide, the spring of 2002was generally cool and wet, whichresulted in slower beetledevelopment and slightly later,more extended flights thannormal in many areas. However,most regions reported that thebeetle flight was closer to normalthan it has been in the last fewyears.
Late, extended flight patterns inthe Prince Rupert, Prince Georgeand Cariboo Forest Regions haveresulted in larvae overwintering invarious instars, the majority ofwhich are smaller than usual.Smaller larvae are generally moresusceptible to cold temperaturesbut recent winter weatherconditions have been too mild tocause significant mortality.
Following a cool wet spring mostof the province experienced a drysummer and fall (with the excep-tion of Prince George ForestRegion and Invermere ForestDistrict). The moisture stressedtrees were often too weak toproduce pitch tubes in response tobeetle attack. This was particu-
larly true when combined withlate beetle flights when the treeswere shutting down, or in areaswhere high beetle pressureresulted in heavy beetle attack pertree, such as in the southwestportion of Vanderhoof TSA. Incontrast, the attacked trees in therest of the Prince George ForestRegion tended to have normalpitch tubes. An anomaly occurredin the Ootsa Lake and ChelaslieArm areas of the Prince RupertForest Region, where mountainpine beetles attacked only high upthe boles of the trees.
All recorded areas of mountainpine beetle attack are based onaerial detection of new red trees,which are actually trees attackedand killed approximately one yearprior. Currently attacked treesremain green until the growingseason the spring followingattack. Therefore, ground surveysare required to determine theratio of undetected "green attack"vs. the recorded "red attack".
10
Lodgepole pine trees affected by
Dothistroma needle blight
Table 4. Green to red mountain pine beetle attack ratios observed in 2002.
Pitch tubes and frass resulting from
mountain pine beetle attack
Region High Range Low Range
Cariboo 27:1 to 40:1 (All districts) 3:1 to10:1 (100 Mile House and Horsefly Districts)
Kamloops 8:1 to10:1 (All districts) 1:1 (Clearwater District)
Nelson 12:1 to 20:1 (Cranbrook and Invermere Districts) 1:1 to 3:1
Prince George 5:1 to 10:1 (Prince George and Vanderhoof Districts) 1:1 to 3:1
Prince Rupert 10:1 (Morice District) 2:1 (Bulkley District)
Table 4 details green to red ratiosobserved throughout the provincein 2002. The highest ratio in theprovince was reported for variousareas in the Cariboo Forest Re-gion, where the ratio reached40:1. Several new infestations inWilliams Lake and Horsefly ForestDistricts were reported to containover 100 green attacked trees withno red attack in the vicinity.However, green to red ratios mustbe interpreted carefully. Excep-tionally high ratios (usually
greater than 5:1) may indicatethat the sampling was done inareas that were being inundatedby beetles from a neighbouringsource, and may not be trulyrepresentative of the averagesituation. The ratios are a roughestimate of the average number ofnew attacks expected for each redtree.
All indications are that despiteaggressive control tactics, themountain pine beetle populationwill continue to expandprovincially in 2003, barring asignificant cold weather eventduring the winter.
In 2001, the province instituted,through regulation, an emergencybark beetle management areabased on the Provincial BarkBeetle Management Strategy.Within this area, special appraisaladjustments and streamlinedregulatory processes are eligible inspecific situations to promoteexpedited small volume harvest-ing to treat small volumes ofinfested wood. Small patchremoval is used as a controlmethod on small isolated new
Pine Needle Diseases
Pine needle cast,Lophodermella concolor
Dothistroma needle blight,Mycosphaerella pini
Pine needle casts, such asLophodermella concolor, affectlodgepole pine trees of all ages.Needles are only infected duringtheir first year of growth duringmoist summers and they do notturn red until the following spring.Growth reduction and occasionalmortality may result after years ofrepeated defoliation, particularlyin younger trees.
infestations and on the leadingedge of the outbreak whereaggressive treatment is beingapplied to slow the expansion andsuppress beetle populations.
11
some degree by Dothistroma, and1219 ha had <50% maximum livecrown left on the pine within theentire opening. At least somemortality has occurred on 1,350ha and trees in 455 ha havesustained >10% mortality. Thisfoliage disease is even causing asmall amount of mortality inmature lodgepole pine.
Ground surveys of the mostheavily infected stands are pres-ently underway, and they confirmthe aerial estimates. Replantingof 800 ha over the next two yearswith shade tolerant species (dueto a well established deciduousoverstory) is planned for openingswith unacceptable levels of deadand dying lodgepole pine.
55 year old lodgepole pine affected by Dothistroma needle blight
Dothistroma (red band) needleblight attacks needles of all ages,any time conditions are suitablefor spore release and germinationduring the growing season; hencedamage to lodgepole pine can befar more devastating in a shorterperiod of time than that whichoccurs with needle casts.Immaturestands can sustain significantmortality, and even maturestands can be seriously affected.
For both foliage diseases, theaerial overview survey likelyunder-represents the actual areaaffected due to the difficulty inaccurately identifying damage toolder foliage and because thesurvey is not conducted at theideal time.
The Cariboo Forest Region was theonly region in the province tohave a significant number ofhectares infected with pine needlecast in both 2001 and 2002.Aerial overview surveys detected265,930 ha of infected lodgepolepine in 2002. The majority of theinfected stands were found in theWilliams Lake and ChilcotinForest Districts at 42% and 34%,respectively. In 100 Mile HouseForest District 35,053 ha weremapped as affected, but thisdistrict was surveyed somewhatlate and it was estimated thatdouble the identified hectareswere actually infected. Pineneedle cast infected 1,884 ha inthe Prince George Forest Region.Infestations remained minor inthe Kamloops and Nelson ForestRegions (under 500 ha) for thesecond consecutive year.
Unprecedented levels of infectionin immature pine stands byDothistroma needle blightcontinued in the Prince RupertForest Region. The disease hasspread considerably and impactshave intensified since 2000. Themajority of affected stands werelocated in the Kispiox TSA,Cranberry TSA and Nass TSA inthe Interior Cedar Hemlock andCoastal Western Hemlockbiogeoclimatic zones.
A project was undertaken toconduct low level aerial surveysover 21,000 ha of immaturelodgepole pine leading stands inthe Kispiox and Cranberry TSAs toassess incidence levels andpotential timber supply impacts ofDothistroma needle blight. Theresults showed that only 7% of thestands had no obvious symptomsof the foliar disease; 16,055 hahad 100% of the trees affected to
12
Comandra blister rust, Cronartium comandraeStalactiform blister rust, Cronartium coleosporioides
Western gall rust, Endocronartium harknessii
Pine stem rusts are prevalent onlodgepole pine throughout BC.Trees of all ages can be infected,but damage is greatest in youngpine stands. Infections can reducetree growth, lead to seriousdefects, and cause tree mortality.It is uncommon to be able toidentify rust mortality during anaerial overview survey, as thedead trees are usually small andtend to be scattered.
Various studies of stem rustincidence and impact on younglodgepole pine are underwaythroughout the province. Oneproject has recently been
completed in the Lakes TSA in thePrince Rupert Forest Region. From1995 to 2001, 331 cutblocks ofprimarily young lodgepole pinewere sampled (total of 15,039ha). Stem rusts were observed in99.7% of the sampled stands:
percentages of the stands found ineach incidence class were 25.3%low (<10%), 36.4% moderate (10-20%), and 38.3% high(>20%). High incidence levelswere frequently found adjacent tolong straight openings wherewinds were frequent or persistent.High incidence areas were mostoften clustered, and ecosystemclassification did not seem to becorrelated with rust incidence.Many of the stem infections datedback to the year 1992; a yearwhen weather conditions seemedfavorable for infection.
From 1982 to 1999 in the CaribooForest Region, a series of perma-nent sample plots were estab-lished in young lodgepole pinestands across the region in variousbiogeoclimatic zones. Each plotwas set up in an area with aspecific forest health concern, to
assess pest incidence and impactand the spread of specific foresthealth factors or pest complexesthroughout a stand over time.The specific focus of eight of theseplots is stem rusts. The plots havebeen assessed several times, mostrecently in the fall of 2002. Resultsare being analyzed over thewinter.
DAMAGING AGENTS OF DOUGLAS-FIR
Pine Stem Rusts
Stalactiform blister rust infection on
young lodgepole pine stem
Western Spruce Budworm, Choristoneura occidentalis
The western spruce budworm is aserious defoliator of interiorDouglas-fir in BC. Outbreaks ofthis budworm cause significantdamage via larval feeding on thefoliage, resulting in reduced seedproduction due to damagedcones, growth loss, topkill,creation of stem deformities andeven mortality, particularly withthe understory.
Defoliation by the western sprucebudworm has expanded substan-tially over the last three years,particularly in the Cariboo andKamloops Forest Regions. Totaldefoliation by western sprucebudworm in the province hasquadrupled in area from 2001 to2002, to a total of 487,352 ha(Figure 5). As in 2001, the major-ity (82%) of the total defoliation
occurred in the Cariboo ForestRegion, primarily south ofWilliams Lake to Meadow Lake,and around the Clinton area. Thesevere defoliation experienced inthe 108 Mile House area over thepast several years declined signifi-cantly this year. Most of theKamloops Forest Region defolia-tion occurred in the Princeton andAspen Grove areas of the Merritt
13
0
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250,000
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350,000
400,000
450,000He
ctar
es o
f Def
olia
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2000 2001 2002
Year
Kamloops
Cariboo
Figure 5. Change in hectares of western spruce budworm defoliation inKamloops and Cariboo Forest Regions.
District, and in the northwesternportion of Kamloops ForestDistrict. In the majority of theKamloops Forest Regiondefoliation was light, while thedefoliation in the Cariboo wasapproximately two-thirds lightand one-third moderate.
Infestations in the VancouverForest Region continued toexpand, up from 1,492 ha in 2001to 3,645 ha in 2002. Defoliationwas mapped in the Boston Barand Nahatlach portions of
Table 5. Summary of fall 2002 western spruce budworm egg mass survey results for districts where moderate to severe defoliation is predicted.
Chilliwack Forest District, and theBirkenhead and Halymore areasof Squamish Forest District.Defoliation intensity increasedfrom primarily light in 2001 tomoderate in over half the areasthis year.
Egg mass surveys conducted in thefall predict further significantdefoliation for next year, particu-larly in the Williams Lake, 100Mile House, Merritt and KamloopsForest Districts (Table 5). Themajority of the predicted
defoliation is in previouslyuninfected stands.
High value stands with predictedmoderate to severe defoliationcan be treated with the biologicalcontrol agent Bacillusthuringiensis var. kurstaki (B.t.k.).Cariboo Forest Region treated23,111 ha and Kamloops treated4,548 ha in the spring of 2002.Kamloops Forest Region hadplanned on treating a larger area,but deleted some planned sitesdue to population declines. Thetreatments were successful, withegg mass counts predicting lowdefoliation for 2003 in treatedareas. The areas where significantwestern spruce budworm defolia-tion is expected in the Kamloopsand Cariboo Forest Regions will beevaluated to determine if they fallwithin treatment criteria (asdetermined by a new provincialdefoliator strategic plan which isunder development). Infestationsin the Vancouver Forest Regionare expected to expand andintensify. No treatments areplanned at this time.
Western spruce budworm larva
No. of sites in each defoliation category
Forest District Nil Light Moderate Severe Average # egg masses/10m2
foliage Lillooet 0 5 1 0 30.0
Williams Lake 3 23 14 0 44.4
100 Mile 4 64 23 1 44.7
Penticton 0 5 4 0 56.2
Merritt 0 47 60 1 63.2
Kamloops 1 6 14 0 63.3
Chilliwack 0 0 3 0 110.3
14
Douglas-fir beetle, Dendroctonus pseudotsugae
Douglas-fir beetle is an importantpest of mature Douglas-fir in BC.At low population levels, thebeetle infests scattered, stressedtrees and windthrow. However,Douglas-fir beetle populations canquickly build under favourableconditions, at which time largenumbers of healthy trees can beattacked and killed. Drought, fireor significant windthrow/break-age from ice are often theprecipitators of outbreaks.
Hectares attacked by Douglas-firbeetle across the provincedeclined from 14,500 ha last yearto 9,078 ha (Figure 6). Althoughthe total hectares affected by thebeetle are comparatively minor,the attacked trees are frequentlylocated in old growth manage-ment areas or within valuablemule deer winter range.
Figure 6. Change in hectares affected by Douglas-fir beetle in BC from2000 to 2002.
Nelson Forest Region continued toexperience the largest decline inaffected hectares, from 7,836 hain 2000 to 885 ha in 2002. Themost significant decline occurredin Invermere Forest District, wherelevels dropped from 2,522 ha lastyear to 55 ha. This was attributedin part to a general decline in thepopulation, but also to aggressivecontrol measures which includedharvesting infested timber andconducting a large lethal funneltrap program (utilizing insecticidestrips containing the activeingredient Dichlorvos).
Prince George Forest RegionDouglas-fir beetle infestations alsodropped dramatically to endemiclevels throughout the region.Douglas-fir beetle attack in theKamloops Forest Region dropped37% from 2001, with local
collapses primarily caused byheavy predation. However, newspot infestations were found tohave very healthy populations.This bark beetle continues to be aproblem throughout the Douglas-fir stands in the transition wet beltareas of Salmon Arm andClearwater Forest Districts.
The largest increase in affectedhectares occurred in the CaribooForest Region, with a 32% gainover 2001 to 5,114 ha (Figure 6).The majority of the attackoccurred in small infestationsalong the Chilcotin and FraserRiver corridors. Active areas ofDouglas-fir beetle in 100 MileHouse Forest District were locatednear Young Lake and Loon Lake.
Vancouver Forest Region had thelowest level of Douglas-fir beetleattack, though hectares affecteddid rise from 93 ha to 372 ha. Themajority of the attack centers werelocated in the Skagit Valley.
The Canadian Forest Service and aUBC Faculty of Forestry graduatestudent have been working withthe Kootenay Lake Forest Districton the development of asusceptibility rating system forstands in the West Arm that arebeing attacked by Douglas-firbeetle. The study first focussed ontree variables that influencedsusceptibility. Age, diameter,height, phloem thickness, barkthickness and growth rate werefound to be significant variables.
15
Douglas-fir tussock moth larva
A more recent addition to thestudy measured water useefficiency by analyzing theamount of carbon 13 relative tocarbon 12 in trees. The resultssuggested that infected trees hadbeen subjected to higher droughtstress than non-infected trees.
The study also looked at standvariables. Preliminary resultssuggest that live crown ratio is animportant variable. This mayindicate that the hazard rating forDouglas-fir beetle is morecomplicated than for other barkbeetle species and should take intoaccount several other standvariables not included in currenthazard rating methods.
Douglas-fir beetle gallery
Douglas-fir tussock moth, Orgyia pseudotsugata
Defoliation of a Douglas-fir stand north of Cache Creek by
Douglas-fir Tussock Moth
The Douglas-fir tussock moth is adestructive defoliator of Douglas-fir of all ages. Since the larvaeconsume both old and newfoliage, one year's defoliation canresult in top kill and mortality.Historically, infestations haveoccurred in thedriest parts of thesoutherninterior,primarily inthe KamloopsForest Region.
Pheromone trapping sites are usedto monitor the population in highhazard areas in Kamloops ForestRegion and the southern part of100 Mile House Forest District.Trap catches in 100 Mile HouseDistrict have not reached the
threshold where significantdefoliation is expected, thoughtrap catches have slowly climbedagain from a sharp drop in 2000.The highest trap catches were in
the areas of ClintonCreek, Bonaparte River
and Loon Lake.Trap catchesin theKamloops
Forest Region in2001 indicated a
building popula-tion that would
probably reach outbreak propor-tions in 2002. However, extensiveparasitism occurred in the fall of2001, and no treatment wasnecessary in 2002 (only 92 ha ofvisible defoliation was mapped
during the overview surveys).
16
Western False Hemlock Looper, Nepytia freemani
The western false hemlock looperis found primarily in the drierportions of southern BC. Itsprimary host is Douglas-fir,though other conifersare sometimesattacked. The larvaeconsume both oldand new foliage, anddefoliation can besevere, resulting intop-kill and mortality.
Hectares defoliatedby the western falsehemlock looperexpanded substan-tially in the NelsonForest Region in 2002.The main infestationwas located in the Eager Hillsoutside of Cranbrook, where 2,558ha of Douglas-fir stands of all ageclasses were defoliated. Themajority of the defoliation was
severe but buds were surviving;therefore, significant mortality isnot expected. The remainder ofthe defoliation in the region
occurred in the Invermere ForestDistrict near Radium Hot Springs,Invermere, and Fairmont. Theseverity of defoliation was evenlysplit between light and moderate
Western false hemlock looper defoliation in Cranbrook District
in these areas. Most of theinfested areas in Invermere ForestDistrict coincided with areas beingset up for ecosystem maintenance
burning by theKootenay NationalPark to restore openrange for bighornsheep habitat.Sampling across theregion showed anexpected populationdecline next year.
The only other noteddefoliation by thewestern false hemlocklooper was 512 ha oflight and moderate
defoliation in the KamloopsForest District at Inks and MowichLakes, where it was combinedwith western hemlock looperdefoliation.
DAMAGING AGENTS OF SPRUCESpruce beetle, Dendroctonus rufipennis
The spruce beetle is the mostdestructive damaging agent ofmature spruce in BritishColumbia. At low populationlevels, the spruce beetle prefers toinfest weakened trees and downedhost material. If a significantamount of a food source such aswindfall is available, populationscan build to the point of outbreak,where beetles will then move intohealthy trees and causewidespread mortality.
Recorded incidence of sprucebeetle attack totaled 268,995 haacross the province in 2002, upmore than 2 ½ times over 2001.Of this total 61% of the hectaresaffected sustained light mortality,35% moderate mortality, and only4% severe mortality. Severity andhectares affected by spruce beetletend to be underestimated fromthe air, as newly killed trees onlyshow as a dull yellowish or redcolour at best, and sometimes justchange directly from green to
grey. The transition period forcolour change is also very short,and can be missed during anoverview survey. This may in partexplain the large drop in thespruce beetle in Prince RupertForest Region which was surveyedrelatively early in the season,versus the large increase in sprucebeetle in the Prince George ForestRegion, which was surveyed later.
Hectares affected by spruce beetlein the Prince George Forest Region
17
increased almost eight fold from2001 to 2002 (Figure 7). Over253,159 ha of attack weredetected this
year acrossthe region.Infestationswere upsubstantiallyin all thedistricts withthe excep-tion of FortSt. John,wherepopulationsdropped toendemiclevels (notethat not allof the districtwas flown). The highest level ofattack was recorded in the PrinceGeorge Forest District, where 65%of the total hectares for the regionwere located.
Infested hectares in the PrinceRupert Forest Region droppedfrom 65,226 ha in 2001 to 8,631
ha in 2002.Groundsurveysconfirm thatspruce beetleis generallyon thedecline in theregion, inpart due toaggressivetrap treeprograms.Infestationsdropped inall districts.The LakesForest
District showed 5,556 ha stillaffected, which represents 64% ofthe regional total.
In the Cariboo Forest Region, totalhectares infested by spruce beetle
0
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Figure 7. Hectares affected by spruce beetle, for regions with more than4000 ha infested.
rose modestly from 1,197 ha in2001 to 4,692 ha in 2002 (Figure7). The majority (93%) of theattack occurred in 100 Mile HouseForest District in the Hendrix Lakeand Spanish Creek area, adjacentto an active infestation in WellsGray Provincial Park. Some areas,up to 150 ha in size, had 98% ofthe trees attacked.
The remaining three southernregions experienced low levels ofspruce beetle infestation. InKamloops Forest Region, 1,024 haof spruce beetle were recorded,primarily in the Lillooet ForestDistrict, near Carpenter Lake andsouth of Anderson Lake.
Hectares affected in VancouverForest Region increased to 1,423in 2002, with infestations prima-rily located in the Haylmore Creekarea of the Squamish ForestDistrict. In Nelson, small scat-tered spots totaled only 74 haacross the region.
Spruce foliar disease,Rhizosphaera kaukhoffii
An unusual foliar disease,Rhizosphaera (identified insamples sent to Brenda Callan,Canadian Forest Service) wasnoted in the Morice Forest Districtof Prince Rupert Forest Region. Atleast ten openings with juvenilespruce (<10 yrs. old) were foundto be 100% affected by this foliardisease. All foliage below 1.5meters was affected, but budswere unaffected. Infected foliagebecame visible in the spring, andremained on the trees throughoutthe summer.
Spruce beetle infestation
18
DAMAGING AGENTS OF TRUE FIREastern spruce budworm, Choristoneura fumiferana
2-year budworm, Choristoneura biennis
Both the eastern spruce budwormand 2-year budworm aresignificant defoliators of all agesof true firs and spruce. Severedefoliation can occur due to lateinstar larvae feeding on old andnew foliage. Several consecutiveyears of defoliation can result ingrowth loss, tree deformity, topkilland tree mortality. 2-yearbudworm is common in thesubalpine and boreal forests of theBC interior, and eastern sprucebudworm is found in northeasternBritish Columbia.
Eastern spruce budwormcontinued to be a chronic problemin the Prince George ForestRegion, primarily in the FortNelson Forest District and someareas in the Fort St. John ForestDistrict. Unfortunately, condi-tions did not allow for aerialsurvey of the defoliation in 2002,so it is not known if there has beena change from the 1.6 millionhectares of affected forestsreported in 2001. Based on localobservations, defoliation levelsseemed to be lower than last yearwith the exception of plantations,where defoliation was estimatedto be moderate to severe. Branchsamples from affected areas in theFort Nelson Forest District werecollected and early instar larvaeemerging from the samples werecounted in order to predict ex-pected defoliation levels for 2003.The sample results indicated
moderate defoliation next year atfour of the six survey sites (ClarkeLake, Snake River P-2, Kotcho andMuskwa) and light defoliation atthe other two sites. Neighbouringinfestations in Alberta have alsobeen sampled and results indi-cated increases in eastern sprucebudworm populations for 2003.
The 2-year budworm requires twoyears to complete its life cycle.Most defoliation damage occurs inthe 2nd year, when larvae are
bigger and hence consume largeamounts of foliage. In the PrinceGeorge Forest Region, 24,080 haof mainly light defoliation wereobserved. Prince George ForestDistrict contained 73% of theaffected hectares, and the remain-der was located in Robson ValleyForest District (particularlyaround Valemount). This is the2nd year in the budworm life cyclefor these districts. Infestations
were present in the Fort St. JamesForest District, but since thebudworm was in the 1st year of itslife cycle, defoliation was notvisible from the air. TheCanadian Forest Service, led byDr. Vince Nealis, conducteddefoliation assessments on anumber of permanent sampleplots in the region. They areworking to develop a method ofpredicting 2nd year defoliationfrom 1st year defoliation. Theresults have not been tabulated todate, but there appears to be ageneral trend towards decreasingpopulations in the surveyed plots.
In the Cariboo and KamloopsForest Regions, the 2-yearbudworm is in its 2nd year.Consequently, mappeddefoliation was up substantially.A total of 71,885 ha were affectedin the upper elevation wet beltareas of the Cariboo, with 78%recorded as light defoliation.Two-thirds of the defoliationoccurred in the Horsefly ForestDistrict, with the rest roughly splitbetween Quesnel and 100 MileHouse Forest Districts. InKamloops, 64,203 ha of defolia-tion was recorded, the majoritybeing of light intensity andlocated mostly in the wettersubalpine areas of the ClearwaterForest District. Eggmass samplingconducted in the fall of 2002generally predicted moderatedefoliation for 2004.
2-year budworm defoliation
on balsam fir tree
19
Western balsam bark beetle, Dryocoetes confusus
The western balsam bark beetle isthe most important damagingagent of its primary host, maturesub-alpine fir, in British Columbia.This bark beetle and an associatedpathogenic fungus can beresponsible for extensive treemortality in high elevationecosystems.
In 2002, just under one millionhectares sustained mortality dueto western balsam bark beetle.The annual impact of westernbalsam bark beetle is usually lessthan most bark beetles, becausethe mortality rate per year is verylow. This year, 92% of thehectares affected were lightattack, 7% moderate, and only 1%was severe. This reflects thetypically low percentage ofwestern balsam bark beetle attackper hectare, as compared to thespruce beetle or the mountainpine beetle (Figure 8). However,
western balsam bark beetle attacktends to occur year after year in asusceptible stand, resulting inextensive cumulative damage.
The greatest increases in hectaresaffected by western balsam barkbeetle in 2002 occurred in thePrince George Forest Region,where 566,350 ha were attacked(Figure 9). This is over double thearea noted as infested in 2001.The majority of the attackoccurred in Mackenzie and Fort St.James Forest Districts, at 39% and29% of the regional total,respectively. Infestations haveincreased significantly in all thedistricts, except in Dawson CreekForest District where levelsdropped by almost half, and FortSt. John Forest District wherereported levels dropped from5,002 ha to only 67 ha (note thatnot all of the district was flown).
Prince Rupert Forest Regionexperienced a large drop inwestern balsam bark beetle attackto 251,451 ha, which is 30% of thehectares affected in 2001 (Figure9). Hectares of attack droppedsubstantially in all districts exceptfor Bulkey-Cassiar Forest District,where 119,152 ha affected bywestern balsam bark beetlerepresented almost half of theregional total. Just under 100polygons were surveyed across theregion to determine if westernbalsam bark beetle was properlyaccounted for in the TimberSupply Review (TSR). The studyconcluded that indeed, mostimpacts are included in theVariable Density Yield modelingtool that is used to predict thevolumes for the TSR.
The large fluctuations in hectaresaffected in the Prince George andPrince Rupert Forest Regions maybe in part a result of differingobserver techniques. Due to thevast number of hectares of lowattack levels, some aerial obser-vers tend to record only areassustaining greater than normalattack with primary focus onspruce beetle and mountain pinebeetle, while others record every-thing. A more standardizedapproach will be implemented in2003. In general, nearly allmature sub-alpine fir stands in thenorthern regions have somedetectable levels of damagecaused by western balsam barkbeetle.Figure 8. Comparison of intensity of attack between the major bark beetles
in British Columbia in 2002.
0
10
20
30
40
50
60
70
80
90
100
Perc
ent I
nten
sity
Mountain pine beetle Spruce beetle Balsam bark beetle
Bark Beetle
Light
Moderate
Sev ere
20
Western balsam bark beetle attackmore than tripled in the CaribooForest Region in 2002 for a total of142,817 ha affected. Threequarters of the attack occurred inthe high elevation stands ofHorsefly and Quesnel ForestDistricts, at 43% and 32% of theregional total, respectively. Veryfew sub-alpine fir stands exist inthe Williams Lake Forest District,therefore area attacked was low.Chilcotin and 100 Mile HouseForest Districts contained theremaining attack in small,scattered patches.
The three other regions sustainedsignificantly lower levels of west-ern balsam bark beetle attack, inpart because sub-alpine fir is notas large a component of theirforested ecosystems. Mortalityremained relatively steady in theKamloops Forest Region with24,455 ha affected in 2002 (Figure9). Most high elevation forestssustained low levels of attack.Hectares affected remained verylow in the Vancouver and NelsonForest Regions.
Figure 9. Hectares affected by western balsam bark beetle in British Columbiafor regions with more than 5,000 ha infested.
The fir engraver beetle is a pest oftrue firs and occasionally Douglas-fir and spruce in southern BC.Trees may be partially attackedand survive, or, if beetles massattack, top-kill or mortality canoccur. In the southern part of theNelson Forest Region, particularlyin the Arrow Forest District,
Fir engraver beetle, Scolytus ventralis
0
100,000
200,000
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ares
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Kamloops Cariboo Prince George Prince Rupert
Region
2000
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widespread mortality of grand firoccurred at the lower elevations.The mortality was thought to bedue to a combination of thecontinued drought and the firengraver beetle. Much of thedamage occurred on private land.Grand fir in these areas tends tobe present as a small percentage
Balsam bark beetle infested stand
of mixed stands. Therefore, attackwas very scattered and hard to seeduring the overview survey.Mainly light mortality, totaling111 ha, was recorded for theregion, but the actual totalhectares affected was higher(ground observations).
21
DAMAGING AGENTS OF HEMLOCKWestern hemlock looper, Lambdina fiscellaria lugubrosa
The western hemlock looper is oneof the most destructive defoliatorsof conifers in BC. Westernhemlock is the preferred host, butduring an outbreak, the looperwill feed on a large variety ofconiferous, deciduous and shrubspecies. The larvae are wastefulfeeders of both new and oldfoliage, which can lead to top-killand mortality.
Western hemlock looperpopulations can increase suddenlyto outbreak levels, which canresult in extensive tree mortality.Outbreaks by this defoliator areusually predictable in length:populations rise in the 1st year butvery little defoliation occurs; in the2nd year significant defoliation isrecorded; in the 3rd year infesta-tions coalesce and defoliation is atthe peak; followed by heavy eggparasitism and a collapse in the4th year.
Western hemlock looper infesta-tions increased over six fold from6,801 ha in 2001 to 44,277 ha in2002 across BC. Recorded levels ofdefoliation were 47% light, 36%moderate and 17% severe. Defo-liation continued in the sameareas as last year in the Vancou-ver Forest Region: the west side ofHowe Sound, in the CapilanoWatershed and eastward toChehalis River. These infestationswere ahead of most in the prov-ince and are now in the declinephase. Infested hectares dropped
from a high of 4,445 ha to 2,818ha. Defoliation resulted inpatches of mortality on the westside of Howe Sound. These areaswill be salvage harvested, ifpossible.
In the Cariboo, Nelson andKamloops Forest Regions, thewestern hemlock looper isgenerally in the 2nd year of theoutbreak cycle, and significantdefoliation was recorded for thefirst time during this outbreak inmost areas. The Cariboosustained 24,117 ha of defolia-tion, primarily around QuesnelLake in Horsefly Forest District.
Most of the 10,719 ha ofdefoliation in Nelson ForestRegion occurred in the Columbia
Forest District. The majority of theattack was situated on both sidesof Revelstoke Lake, from MarsCreek to Mica Creek. Larvalcounts at 72% of the permanentsample plots exceeded thresholdvalues for the second consecutiveyear, indicating that visibledefoliation will continue in 2003.The average number of larvae perbeating increased from 32 to 112in the infested plots. Sites withhigh larval counts, other than onRevelstoke Lake, includedlocations at Trout Lake andBeaver River.
Western hemlock looper infesta-tions totaled 7,387 ha in theKamloops Forest Region. Themajority of these infestationsoccurred east and north of Salmon
Western hemlock looper defoliation along Revelstoke Lake
22
Hemlock looper larva
DAMAGING AGENTS OFDECIDUOUS TREES
Forest tent caterpillar, Malacosoma disstria
The forest tent caterpillar is amajor defoliator in BC throughoutthe range of its primary host,trembling aspen. Other deciduoustree species, shrubs and even someconifers can be defoliated duringsevere infestations. Outbreaksoccur periodically across largeareas of susceptible stands.Sustained, severe defoliation canresult in top-kill, reduced growth,and occasional minor mortality.
Infestations by the forest tentcaterpillar were down sharply in2002 to 4,127 ha from 60,415 ha.This continues a downward trendexpressed over the last severalyears. All of the recordedinfestations were located in theVanderhoof Forest District, anddefoliation was primarily light.
Satin Moth, Leucoma salicis
Satin moth is an important
defoliator of all poplars, andoccasionally feeds on willow. Thisinsect was introduced fromEurope, and was first discoveredin southwestern BC in 1920. Sincethen it has spread throughout thesouthern and central interior.Periodic outbreaks often causetotal defoliation of the host, whichcan result in top-kill, growthreduction and occasional treemortality.
Defoliation by the satin mothcontinued to increase in theCariboo Forest Region from 6,575ha in 2001 to 45,070 ha. Defolia-tion levels were moderate in 60%,light in 29% and severe in 11% ofthe affected stands. Part of thelarge increase is attributable tohigher survey accuracy in the
Quesnel Forest District, whereover half of the entire regionaldefoliation was mapped in 2002as opposed to a negligible amountlast year, when it was under-estimated. The remainder of theinfestations were spread through-out poplar stands in the rest of theCariboo districts. The heaviestdefoliation occurred along theQuesnel River and at TatalayokoLake. Infestations in theKamloops Forest Region shrunksubstantially in 2002 to a total ofonly 324 ha.
Serpentine leaf miner, anotherdefoliator of aspen, was present toan extensive degree throughout100 Mile House Forest District.Aerial mapping of this foresthealth pest was not conducted.
Arm in Salmon Arm Forest Districtand Wells Gray Provincial Parkand the upper ends of Raft andMad River drainages in Clear-water Forest District. 702 ha ofdefoliation also occurred in theHidden Lake/Kingfisher areas ofVernon Forest District. Two highlyunusual infestations in lowelevation dry Douglas-fir stands(totalling 512 ha) occurred in thevicinity of Inks and Mowich Lakesin Kamloops Forest District, inassociation with western falsehemlock looper. Moth trapcatches at permanent sample sitesremained high for the third year,with the highest catches in thePerry River and Kingfisher Creekareas.
The biological control agentBacillus thuringiensis var. kurstakiunder the brand name Foray 48Bis now registered for use onwestern hemlock looper infestedstands in Canada. Pendingfunding, operational treatmentsand research trials are planned onapproximately 10,000 ha inNelson, 2,500 ha in Cariboo and2,000 ha in Kamloops ForestRegions for next year.
23
Birch Leaf Miner,Fenusa pusilla
The birch leaf miner wasintroduced into North Americafrom Europe, and can now befound throughout the range of itshost, paper birch, in BC. Damageto the foliage occurs when thelarvae feed between the leaflayers. Severe defoliation canresult in top die-back, minorgrowth loss and tree stress.
Defoliation by the birch leaf minermore than doubled from 2001levels to 9,720 ha in KamloopsForest Region. The majority of theinfestations occurred in theVernon, Kamloops andClearwater Forest Districts.
Substantial defoliation was alsorecorded in the Nelson ForestRegion on 8,464 ha in the Arrow,Columbia and Kootenay ForestDistricts in 2002. Some defolia-tion did occur in Nelson ForestRegion in 2001, but it was notrecorded during the aerial survey.Defoliation recorded as birch leafminer was actually identified as acomplex of various insects. Treesaffected by defoliation incombination with the ongoingdrought are beginning to experi-ence significant dieback in maturestands over many parts of theregion.
Gypsy Moth, Lymantria dispar
The gypsy moth is a seriousdefoliator that causes reducedgrowth and mortality on a widerange of deciduous trees andshrubs, as well as some coniferoustrees. It is an insect that has beenperiodically intercepted in BCsince 1978 but aggressivemonitoring and eradicationprograms have thus far preventedits establishment in BC.
During the past 23 years,province-wide monitoring usingpheromone-baited traps has beenconducted to detect incursions ofgypsy moth in BC and throughoutwestern North America where themoth has not established. Wheretrap catches identify potentialinfestations, eggmass and larvalsurveys are conducted to deter-mine if treatments are warranted.Where a population is detectedand is determined to be on theverge of becoming established,eradication treatments havehistorically been very successfully
Foliage damage caused by birch leaf miner
conducted. In 2002, fifteen mothswere caught during the CanadianFood Inspection Agency’s annualmonitoring survey. Thepheromone traps caught moths atseven different sites: three onVancouver Island, two on theLower Mainland and two in thesouthern interior. Most sitesrecorded only one or two mothswith the exception of the Delta sitethat was trapped using a higherdensity of traps. The Delta sitewas ground sprayed with Btk in2000 and has been “masstrapped” in 2001 (3 mothscaught) and 2002 (6 mothscaught). The two sites in thesouthern interior are associatedwith high-use recreation areaswhere pupae may have beentransported on recreationalvehicles.
A full history of the gypsy moth inB.C. is available on the MOF website at http://www.for.gov.bc.ca/hfp/gypsymoth/.
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Aspen and Poplar Leaf and Twig Blight, Venturia spp.
Aspen and poplar leaf and twigblight infects trembling aspen andpoplars. These fungi are widelydistributed throughout BC.Infected young shoots andterminal leaves are killed.Repeated infections can result ingrowth reduction and stemdeformities, particularly in youngstands.
The unseasonable cool and wetspring weather experienced in thePrince Rupert and Prince GeorgeForest Regions over the last fouryears have provided optimumconditions for the build-up ofinfections by aspen and poplarleaf and twig blight. In PrinceRupert Forest Region, infestationsmore than doubled from 2001 to a
total of 47,239 ha. All districtsexperienced increases except forKispiox Forest District, whereaffected hectares fell. The major-ity of the infected stands werelocated in the Cassiar, Lakes,Bulkley and Morice Forest Dis-tricts. In general, aspen stands
were heavily defoliated in the sub-boreal spruce biogeoclimatic zone,and cottonwood stands sustainedsevere defoliation in the interiorcedar-hemlock biogeoclimaticzone. Trees of all ages wereaffected.
In Prince George Forest Region,infection by aspen and poplar leafand twig blight affected 32,918 hain 2002. This was up sharply fromonly 162 ha recorded the previousyear. Defoliation was recorded inall districts, but was most preva-lent in Dawson Creek and Fort St.James Forest Districts.
Aspen shoots affected by Venturia
Aspen stand defoliated by Venturia
DAMAGINGAGENTS OF
MULTIPLE HOSTS
Armillaria Root Disease,Armillaria ostoyae
Armillaria root disease occursthroughout the southern portionof BC. A variety of conifers are itsprincipal hosts, though manydeciduous trees and shrubs arealso attacked. Armillaria cancause growth loss and minor buttrot in diseased trees, howevermortality is very common. Incoastal forests, observed mortalityseldom occurs in trees older thanabout 25 years but in the interiortrees of all ages are killed.Although Armillaria root diseasecenters can be identified from theair, they are not usually seenduring an overview survey due tothe height and speed of theaircraft.
A survey of Armillaria incidenceand impacts in managed forestareas was recently completed inthe Invermere TSA. A total of 561harvested or designated forharvest blocks were examined forevidence of Armillaria. The pre-harvest forest age of the cutblockswas 101 to 120 years. Infectionswere confirmed on 76% of theblocks through a survey of treesand stumps using transects thatcovered approximately 5% of eachblock. The weighted averageinfection using above groundArmillaria signs was 8.1%. Areaswith lodgepole pine and/or
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Douglas-fir had the most frequentoccurrence of Armillaria rootdisease and the highest incidenceof infected area per block. Inseveral blocks, Armillaria induceda change in tree species composi-tion from initially establishedDouglas-fir to less-susceptiblespecies. In a few blocks, reforesta-tion efforts failed. The results ofthese surveys substantiateprevious opinions about thewidespread occurrence andpotentially major impacts ofArmillaria root disease on forestproductivity in the Invermere TSA. cooperation of many major forest
licensees, including Lignum Ltd.,Riverside Forest Products Ltd.,Weldwood of Canada Ltd., WestFraser Timber Co. Ltd., Tembec(formerly CFI) as well as withseveral woodlot holders and theSmall Business Program.
The main focus of the work hasbeen to inoculate stumps inlogged areas with a saprophyticfungus (Hypholoma fasciculare),with the hope that it can competewith the fungus that causesArmillaria root disease(Armillaria ostoyae in the BCinterior). Initial results from fiveand six year old trials indicatethat mortalities are significantlylower in Hypholoma treated areasthan in untreated areas. Treatedareas have mortality rates thatare 1/3 (or less) of those inuntreated areas. Further ques-tions include: will these types ofresults occur over a wide range ofconditions and; will Armillariacaused mortalities begin toincrease over time, similar to whathappens in stumped areas, or will
the Hypholoma remain effectiveover time and continue to reducemortalities.
This research into the use ofHypholoma has explored acommonly held theory about themechanisms that limit Armillaria
in nature. It is postulated by theresearchers that after standdestroying events, the populationsof various saprophytic fungi risedramatically with the inputs offresh bole and other woodymaterial and these saprophyticfungi may outcompete rootdisease fungi in woody substrate(roots). It is suggested that thisnatural process never fullyeliminates root disease organisms,but lowers their inoculumpotential for several decades, sothat well-stocked stands are ableto establish. To test this hypoth-esis, many of the new trials con-tain a component of woody debrismanagement. All trials are at theresearch (not operational) level atthis time. For more information,contact Dr. Bill Chapman,([email protected]).
Since 1992, Dr. Bill Chapman(Research Section, Cariboo ForestRegion) and Dr. Guoping Xiaohave been conducting researchinto possible innovative methodsto control Armillaria root disease.Several research trials have beenestablished in the Nelson andCariboo Forest Regions. The workhas been done with the
Armillaria root disease center
Armillaria mycelial fan beneath Douglas-fir bark and a fruiting body
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Climatic InjuryTree species of all ages can beaffected by a variety of climaticinjuries, including drought, flood-ing, windthrow, frost, red belt andsnow. Damage can vary fromslight growth reduction to serioustree deformities and mortality.Additionally, trees damaged byclimatic injuries are often moresusceptible to insects and disease.
Mortality caused by floodingcontinued to be the most signifi-cant climate related damageagent in BC, affecting 4,902 ha.Nearly 100% of the damageoccurred in the three most north-ern regions, due to unseasonablywet and cool spring weather overthe last four years.
Windthrow or blowdown was notrecorded as a significant damageagent in 2002 during the aerialoverview survey. However,approximately 1000 ha in theWigwam area of the CranbrookForest District were identified byground surveys. The forest in thisarea was a lodgepole pine/Doug-las-fir mix 60 to 80 years old. Thissite will be monitored for a possi-ble increase of Douglas-fir beetleand Ips spp. beetle (commoncolonizers of recently killed anddamaged trees).
Drought affected 78 ha in theSquamish Forest District. Vancou-ver Forest Region has been drierthan average for several yearsnow, and further droughtmortality is expected in 2003.
AnimalsA variety of animals cause dam-age to various tree speciesthroughout BC, particularly at theseedling to sapling stages. Animalfeeding is responsible for themajority of the damage, whichcan range from foliage browsingto tree girdling, through barkstripping. Damage can alsooccur from rubbing and tram-pling. Most animal damage isnot visible during aerialsurveys. The most visibledamage is stem girdling, result-ing in dead tops or mortality.Bear and porcupine are mostoften responsible.
In 2002, black bear damageaffected 796 ha in Nelson ForestRegion, primarily in the Columbiaand Invermere Forest Districts.Although black bear damage inthe Vancouver Forest Region wasnot surveyed this year, damage
has spread and intensified. Porcu-pine damage affected 5,717 ha inPrince George Forest Region, withmost of the damage located inPrince George Forest District onlodgepole pine. An additional 527ha of porcupine damage wasmapped in Prince Rupert ForestRegion, primarily in the Kalumand North Coast Forest Districts.This mapped area is probablyunderestimated based on groundsurvey information that indicatesdamage is widespread andsomewhat chronic throughoutmany drainages in these twodistricts. It is difficult to accu-rately detect chronic porcupinedamage using the overview surveymethod, particularly in hemlockstands. Almost all of the porcu-pine damage in the province wasof very light intensity.Bear damage to young pine
American porcupine
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BC Ministry of Forests Forest Health Links on the World Wide Web:
BC Ministry of Forests forest health home page:http://www.for.gov.bc.ca/hfp/forsite/Forest_Health.htm
Forest health aerial overview surveyhttp://www.for.gov.bc.ca/hfp/forsite/overview/overview.htm
Standardized forest health aerial overview survey standards for British Columbia:http://srmwwww.gov.bc.ca/risc/pubs/teveg/foresthealth/index.htm
Aerial overview digital data standards:http://www.for.gov.bc.ca/hfp/forsite/overview/arcinfo.htm
Aerial overview survey data on MOF FTP server:ftp://ftp.for.gov.bc.ca/branches/forest_practices/external/!publish/Aerial_Overview/
Bark beetles in BC:http://www.for.gov.bc.ca/PAB/News/Features/beetles/index.htm
Field guide to forest damage in British Columbia:http://www.for.gov.bc.ca/hfp/forsite/pest_field_guide/index.htm
Ministry of Forests, Forest Practices Branch
Many thanks to the contributors to this document:Data and specialized project information:
Forest Practices Branch - Tim Ebata, Forest Health Project SpecialistJohn Muir, Forest Pathologist
Cariboo Forest Region - Leo Rankin, Forest EntomologistBill Chapman, Research Soil Scientist
Kamloops Forest Region - Lorraine Maclauchlan, Forest Entomologist
Nelson Forest Region - Art Stock, Forest EntomologistPrince George Forest Region - Robert Hodgkinson, Forest Entomologist
Richard Reich, Forest PathologistPrince Rupert Forest Region - Ken White, Forest Entomologist
Alex Woods, Forest PathologistVancouver Forest Region - Don Heppner, Forest Entomologist
Stefan Zeglen, Forest PathologistInvermere Forest District- Emile Begin, Forest Health OfficerCanadian Forest Service - Terry Shore, Research ScientistM.E. Ferguson ConsultingR. Stewart ConsultingTimberland Consultants (2001)Pro-Tech Forest Resources Ltd.
Photographs:Liz Goyette - Cranbrook Forest District (Western False Hemlock Looper)Alex Woods - Prince Rupert Forest Region (Dothistroma)Joan Westfall - EntoPath Management Ltd. (various)
Drawings:Soren Henrich - Henrich Design and Illustration
Maps:Duncan Richards - HRGISolutionsResource Tenures and Engineering Branch
Editing:Tim Ebata - Forest Practices Branch, Forest Health Project Specialist
Prepared by:Joan Westfall
