ARNEWS Annual Report 1993 Rapport annuel 1993 sur le...

ARNEWS Annual Report 1993

Rapport annuel 1993 sur le DNARPA

ARNEWS Informe Anual 1993

J. Peter HallCanadian Forest Service / Service canadien des forêts

Information Report / Rapport d’information / Informe ST-X-9

Ressources naturellesCanada

Service canadiendes forêts

Natural ResourcesCanada

Canadian ForestService

0 1250 km

Arctic Cordillera/Cordillère arctique/Cordillera ártica

Northern Arctic/Haut-Arctique/Artico norte

Atlantic Maritime/Maritime de l'Atlantique/Zona marítima del Atlántico

Boreal Shield/Bouclier boréal/Meseta boreal

Taiga Shield/Bouclier de taïga/Meseta de taiga

Southern Arctic/Bas-Arctique/Artico sur

Taiga Plains/Plaines de taïga/Llanos de taiga

Taiga Cordillera/Cordillère de taïga/Cordillera de taiga

Prairie Plains/Plaines de prairies/Planicies de los Llanos

Boreal Plains/Plaines boréales/Llanos boreales

Mixedwood Plains/Plaines à forêts mixtes/Llanos de bosques mixtos

Montane Cordillera/Cordillère montagnarde/Cordillera subalpina

Pacific Maritime/Maritime du Pacifique/Zona marítima del Pacífico

Boreal Cordillera/Cordillère boréale/Cordillera boreal

Hudson Plains/Plaines hudsonniennes/Llanos de la bahía Hudson

Ecozones/Écozones/Zonas ecológicas

ARNEWS Plots/Parcelles du DNARPA/Parcelas del ARNEWS

Canada’s ecozones and locations of ARNEWS plots. (PNFI 1991)Écozones du Canada et position des parcelles du DNARPA. (IFNP 1991)

Las zonas ecológicas de Canadá y las parcelas del ARNEWS en esas zonas. (PNFI 1991)


Rapport annuel 1993 sur le DNARPA

ARNEWS Informe Anual 1993

Compiled by/Compilation par/Preparado por

J. Peter HallScience and Sustainable Development Directorate/Direction des sciences et du développement durable

in cooperation with officers of the Forest Insect and Disease Survey/avec la collaboration des agents du Relevé des insectes et des maladies des arbres:

G.A. Van Sickle, R. TurnquistPacific and Yukon Region / Région du Pacifique et du Yukon

J.P. BrandtNorthwest Region / Région du Nord-Ouest

A. HopkinOntario Region / Région de l’Ontario

S. D’Eon Petawawa National Forestry Institute / Institut forestier national de Petawawa

P. Desrochers, D. LachanceQuebec Region / Région du Québec

L.P. Magasi, J.E. HurleyMaritimes Region / Région des Maritimes

W. Bowers, D. StoneNewfoundland and Labrador Region / Région de Terre-Neuve et du Labrador

Information Report / Rapport d’information / Informe

ST-X-9

Published by/Publié par/Publicado por

Canadian Forest Service / Service canadien des forêts Science and Sustainable Development Directorate/Direction des sciences et du développement durable

Ottawa, 1995

©Her Majesty the Queen in Right of Canada 1995Catalogue No. Fo29-33/9-1993ISBN 0-662-62004-6ISSN 1188-2891

Copies of this publication may be obtained free of charge from:Natural Resources CanadaCanadian Forest ServiceOttawa, Ontario K1A 0E4

A microfiche edition or copies of this publication may be purchased from:Micromedia Ltd.240 Catherine St., Suite 305Ottawa, Ontario K2P 2G8

Editing and production: Paula IrvingLayout: Danielle Monette

Cataloguing in Publication Data

Canadian Forest Service. Science and Sustainable Development Directorate

ARNEWS annual report = Rapport annuel …surle DNARPA = ARNEWS informe anual

1990-Annual(Information report; ST-X-9)Text in English, French and Spanish.ISSN 1188-2891 = ARNEWS annual reportCatalogue No. Fo29-33/9-1993

1. Forest conservation — Canada. 2. Acidrain — Canada. 3. Air — Pollution — Canada.I. Title. II. Title: Rapport annuel...sur le DNARPA. III. Title: ARNEWS informe anual.IV. Series: Information report(Canadian Forest Service. Science and SustainableDevelopment Directorate); ST-X-9.

SD414.C32 1993 634.9'619'0971

Printed on alkalinepermanent paperPRINTED IN CANADA

Printed onrecycled paper


Contents

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

ARNEWS and the Terrestrial Ecozones . . . . . . . . . . . . . . . . . . . . . . . . 8

Forest Health and Its Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Forest Health in Canada’s Ecozones . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Atlantic Maritime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Mixedwood Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Boreal Shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Boreal Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Taiga Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Montane Cordillera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Boreal Cordillera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Pacific Maritime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Health of Canada’s Model Forests . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Selected Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

6 ARNEWS Annual Report 1993

Acknowledgments

ARNEWS was conceived and developed and is imple-mented by the Forest Insect and Disease Survey (FIDS) staff ofthe Canadian Forest Service (CFS). This collaborative effortextends to the production of this report which has been preparedfrom regional reports and analyses. FIDS plays a leading role inmanaging ARNEWS through its field, laboratory, analytical,and management staff. ARNEWS is also part of the CFS LongRange Transport of Atmospheric Pollutants (LRTAP) programand is linked to Canada’s Green Plan through the department’s“Partners for Sustainable Development in Forestry” program.

We wish to thank Environment Canada, State of the Envi-ronment Reporting who provided the descriptions of the forestedecozones and located the ARNEWS plots in the ecozones.

Abstract

The Acid Rain National Early Warning System (ARNEWS)has been in place since 1984 to detect early signs of damage toCanadian forests and to monitor changes in forest vegetationand soils. In 1993, ARNEWS was expanded to 150 plots andthe methods for assessing crown condition in conifers and hard-woods were revised.

ARNEWS plots are established and assessed by the ForestInsect and Disease Survey (FIDS) of the Canadian ForestService (CFS). The role of FIDS in ARNEWS is to identifythe types and degree of damage to forests, whether causedby natural factors such as insects, diseases, and weather, oranthropogenic factors such as management practices and airpollution. The health of 20 conifer and 8 hardwood speciesfrom across Canada is described. There has been no indicationof a large-scale decline in forest health and few symptoms ofpollution were observed. Where pollution-like symptomsoccurred, they were usually accounted for by natural factors.Exceptions occur in the Bay of Fundy area of New Brunswickwhere dieback on birch coincides with the presence of acid fogand high levels of tropospheric ozone. Needle flecking hasbeen observed on conifers in Nova Scotia and New Brunswick;its cause has yet to be verified.

Introduction

Canada’s forests are a valuable economic and sociologicalresource whose sustainability is essential to our well-being.Concerns about forest health in the face of environmentalchange led the Canadian Forestry Service (CFS) to establishthe Acid Rain National Early Warning System (ARNEWS) in1984. This national biomonitoring network was designed to

detect early signs of the effects of acid rain on Canada’s foreststo enable action to be taken to forestall anticipated damage.The term “acid rain” encompasses all forms of air pollution —wet and dry deposition of sulfates (SOx), nitrates (NOx), gaseouspollutants (ozone); and airborne particles.

ARNEWS uses a common set of measurements taken onpermanent sample plots established by the CFS Forest Insectand Disease Survey (FIDS) to assess forest health. Datacollected are supplemented by the results of other surveys andinvestigations by FIDS and its cooperating agencies. Thestrategy of the ARNEWS program is to detect early signs ofdamage to forest trees and soils that may have been caused byacid rain by isolating damage attributable to natural causes ormanagement practices, and to monitor the long-term changesin vegetation and soils attributable to acid deposition and otherpollutants. The symptoms of air pollution damage are nothighly specific, and they also frequently resemble damagefrom other causes. The experience of FIDS field technicianstrained to distinguish these symptoms from abnormal climaticconditions, nutrient deficiencies, and the effects of insects anddiseases is crucial to the functioning of ARNEWS.

Plots have been established across Canada in the eightforested terrestrial ecozones. Emphasis was placed on thecommercially important tree species and in areas of knownacid deposition. ARNEWS was designed to assess all foresttypes; however, species that occur sporadically, such as elm(Ulmus sp.), hickory (Carya sp.), and walnut (Juglans sp.), arenot well represented in the network.

Air pollution has subtle effects on tree physiology and soilchemistry and the symptoms may be masked by the effects ofnatural conditions. Many trees assessed as part of ARNEWShave been stressed by weather conditions, insects, diseases, andother processes in forest ecosystems. Individual trees arealtered by stress and become susceptible to insect and diseaseorganisms that attack and may kill them. Usually forestecosystems are not permanently damaged and recover to astate resembling their original condition. It is usually theinteraction of several abiotic and biotic factors that producesan unhealthy forest, rather than the effect of a single factor. Itis in this context that ARNEWS data are interpreted.

Reporting of results began in 1990. This and subsequentanalyses concluded that there was no evidence of large-scaledecline in the health of Canadian forests, although it waspossible that trees had been weakened or stressed by air pol-lution and that this stress was not apparent. Results to dateshow that mortality was generally in the normal range of1 –2% and was attributed to natural factors. Nevertheless,certain instances of forest damage have been observed andpollutants may be involved.

In 1993, ARNEWS was expanded to 150 plots to assessareas that had been underrepresented and to obtain better

ARNEWS Annual Report 1993 7

assessments of the more common and widespread species.Improvements were made in the assessment of crowncondition used to evaluate the health of the trees.

Changes in reporting occurred in 1993 when the data werepresented on the basis of eight terrestrial ecozones, as devel-oped by Environment Canada, State of the EnvironmentReporting branch. This reflects the importance of an eco-system approach to environmental research and decisionmaking.

An early warning system to detect and monitor conditionsremains an essential part of the CFS commitment to thesustainability of Canada’s forests. This is the fourth in theseries of annual reports on the health of Canada’s forests andpresents the results of the 1993 measurements.

Methods

ARNEWS consists of 150 permanent sample plots locatedacross Canada in eight forested ecozones. Most ARNEWSplots are located in semimature, natural forests, where thenumber of trees would normally be expected to declinebecause of competition as the stand matures. Mortality greaterthan 2% often reflects the effects of stress, such as significantinsect defoliation, drought, windstorms, or anthropogeniccauses.

Parameters measured annually, at 5-year intervals, ormore frequently as required are as follows:

A. One or more assessments per growing season1. Insect and disease conditions2. Acid rain symptoms3. Seed production

B. Annual assessments1. Tree mortality2. Tree condition

C. Every 5 years1. Radial growth2. Vertical growth3. Crown structure and density4. Foliage nutrients5. Soil chemistry

The trees in the plots are assessed visually; sampling anddetailed measurements requiring hand-held branch samples aremade on off-plot trees to ensure that trees in the plot are notdisturbed. Measurements reported here are tree mortality, treecrown condition, and the type and degree of foliar damage,including any symptoms of air pollution. Possible symptomsof air pollution are compared with known symptoms of emis-sion toxicity on vegetation followed up by laboratory identi-fication.

In 1992–93, the methods and measurements for assessingtree condition were revised. These revisions were prompted byseveral problems encountered during the measurement processand in the quality assurance/quality control program. Theseimprovements should result in a more reliable, repeatable dataset for the condition of tree crowns.

Tree Mortality

The cause of tree mortality is determined in the field,supplemented by laboratory examination if necessary. The rateof mortality is determined and compared with the “normal”mortality rate, which in most of Canada’s natural forests is1–2%.

Conifer Crown Classification System

Conifers (except larches) are classified according to theamount of crown defoliation. Defoliation is defined as foliagemissing for whatever reason from the normal foliage com-plement. Bare and dead tops are considered defoliated. Thistakes into account the natural loss of needles as a twigmatures. The crown condition classes are:

1 No defoliation.2 Only current foliage defoliated, total defoliation <25%.3 Current and/or some older foliage defoliated, total <25%.4 25–50% total defoliation.5 51–75% total defoliation.6 76–90% total defoliation.7 More than 90%total defoliation.8 Tree died since last assessment.9 Dead tree.

Trees are considered healthy if they are in the first threeclasses. As crown defoliation approaches 40%, the health ofthe tree begins to decline and it becomes susceptible to dam-age by secondary organisms. Recovery is possible but asdefoliation increases in extent and time, the possibility ofrecovery decreases.

Hardwood Crown Classification

The hardwood classification system is based on the visibleparts of the outer crown: the quantity and quality of foliage inthe outer crown, the percentage of the outer crown that con-tains bare twigs, and dead branches. Larches/tamaracks areassessed as if they were hardwoods. The condition of hard-wood tree crowns is assessed according to the following:

10 Full complement of foliage, no visible crown damage.20 Foliage thin, off color, no dead branches or bare twigs.


30 No dead branches, bare twigs in up to 5% of the crown.35 No dead branches, bare twigs in more than 6% of

the crown.40 Dead branches and bare twigs in up to 15% of the crown.45 Dead branches and bare twigs in up to 16–25% of

the crown.50 Dead branches and bare twigs in up to 26–37% of



the crown.65 Dead branches and bare twigs in 76% or more of

the crown.70 More than 50% of the crown dead, only small adventitious

branches present, usually at the base of the crown or stem.08 Tree died since last assessment.09 Dead tree.

Hardwood trees are considered healthy if no branches aredead (classes 10–30). This too is a rough guide, but as crowndieback increases beyond this level the tree becomes less andless able to recover and ward off other damaging insects anddiseases.

Insects and diseases are identified and their levels ofdamage are determined. Observations are made to coincidewith the life stages of the different groups of damagingorganisms. The conifers described are eastern white pine, jackpine, lodgepole pine, red pine, ponderosa pine, tamarack,black spruce, Engelmann spruce, Norway spruce, red spruce,hybrid spruce, Sitka spruce, white spruce, western hemlock,coastal and interior Douglas-fir, alpine fir, amabilis fir, balsamfir, and western red cedar. The hardwoods described includetrembling aspen, white birch, yellow birch, American beech,red oak, black cherry, red maple, and sugar maple.

Data are compiled on the basis of the terrestrial ecozonefor the species assessed in that ecozone in the ARNEWS plotnetwork. Species that occur in more than one ecozone aredescribed in each of the ecozones in which they occur.

Arnews and the Terrestrial Ecozones

In recent years, the value of an ecosystem approach toenvironmental research and decision making has become moreapparent. We must take into account the longer term con-sequences of changes set in motion in an intricately linked anddynamically balanced ecosystem, because factors that affectone part of that ecosystem affect the whole ecosystem.

Environment Canada through State of the EnvironmentReporting (SOER) will be reporting data in 1996 on the basis

of ecozones. Canada has been divided into 17 terrestrial eco-zones, areas that exhibit comparable ecological attributes. Theecozone boundaries are based on climate and soils using ahierarchial system of classification from the landscape to thenational level. Of these 17 ecozones, 8 are forested. TheARNEWS network established in two stages in 1984 and 1993was not selected with the ecozones in mind. Plots establishedin 1984 were placed where pollution levels were thought to bea significant stress on Canadian forests. Those established in1993 considered climate change a major stress on Canadianforests.

This report discusses the health of species located in thefollowing ecozones: Atlantic Maritime, Boreal Shield, Mixed-wood Plains, Boreal Plains, Taiga Plains, Montane Cordillera,Boreal Cordillera, and Pacific Maritime (see the map on theinside back cover of this report). The analysis and evaluationof tree health are based on the ARNEWS network supportedby the results of other surveys by the CFS and other agencies.

Forest Health and Its Evaluation

To ensure forest sustainability, managers need to know thestate of health of these forests so that appropriate actions canbe taken to protect them. However, defining or evaluatingforest health is difficult. Forest health means many things tomany people and it is usually easier to describe an unhealthyforest than a healthy one. Nevertheless, some measure orevaluation of forest health is necessary so that forests can beprotected and information produced for policy decisions.

Evaluating the health of forests at a particular time is com-plicated by the fact that forests are dynamic systems in contin-uous change. Descriptions of forest health therefore includebroad and easily evaluated criteria. Traditional measures offorest health include trends in tree growth and mortality; con-dition of tree crowns; condition of soil, water, and wildlife;frequency and severity of pest outbreaks; and the forest’s vul-nerability to pests. Increasingly, human-caused factors, such asnewly introduced pests, air pollution, and the possible effectsof changes in global climate, are influencing forests and havefocused our attention on the need to ensure forest sustainability.

Healthy forests are resilient and tolerant of stress and arestructurally and functionally complex. Forests respond to acomplex of environmental factors rather than to a single factorsuch as “air pollution.” Other stresses affect forests so signif-icantly that subtle responses such as those caused by pollutionare masked by the variability in the data. Consequently, moni-toring biological responses to pollutant deposition in the fieldis very difficult. The ARNEWS approach is to assess the stateof the health of the forest using a common set of measure-ments on permanent plots. The degree of health is assessed by


comparing the levels of mortality, the condition of the treecrowns, and the presence of symptoms of damage by air pollu-tion. Tree mortality is considered to be at normal levels if it isabout 1–2%, the rate at which natural thinning occurs in unman-aged natural stands. Greater mortality can be expected to occurfrom damage by insects, diseases, weather extremes, or anthro-pogenic causes such as air pollution.

Crown condition is another measurement of forest health.Trees are considered to be healthy as long as there is no branchdieback. This varies with initial tree health, site, and weatherconditions, but as dieback exceeds this level, the tree becomessusceptible to other damaging insects and diseases.

The ARNEWS crews also search for damage caused bypollution. This damage often resembles that caused by naturalfactors, and laboratory determination of cause and effect isusually necessary.

Finally, it is difficult to be certain whether trees or forestsare being damaged by pollution. Cause and effect can beinferred only when there is a strong pattern of consistency,responsiveness, and a demonstrated biological mechanism.Consistency requires that injury must invariably be associatedwith the presence of the suspected causal factor(s). Respon-siveness requires that removal of the pollutant allows treerecovery. Also, a biological mechanism of cause and effectmust be demonstrated. These requirements are difficult tosatisfy but have been demonstrated in certain situations. Policyaction may still be necessary in the absence of incontrovertiblescientific evidence of cause and effect. The fact that we do notknow everything is not an excuse to do nothing or to avoidresponsibility. We do not need to wait until all the effects areproven, and the forests dead, before we act in a scientificallysound and responsible manner.

Forest Health in Canada’s Ecozones

Atlantic Maritime

The Atlantic Maritime Ecozone extends from the mouth ofthe St. Lawrence River in Quebec, southeasterly across NewBrunswick, and into Nova Scotia and Prince Edward Island.The ecozone is dominated by the interior Appalachian uplandand the Northumberland coastal plain. The uplands of NewBrunswick and Nova Scotia are composed of granite, gneiss,and other hard, crystalline rocks. Rough upland terrain is dom-inated by glacial till and humo-ferric soils. The coastal lowlandareas, with their deeper humo-ferric soils derived from marinedeposition and glacial erosion of the underlying sedimentarybedrocks, are the main areas of settlement. Forest stands aremixed coniferous–deciduous characterized by red spruce, bal-sam fir, yellow birch, and sugar maple, with red pine, white pine,and eastern hemlock occurring frequently. Some boreal species

are present including black spruce, white spruce, balsampoplar, and white birch. Jack pine is prominent on sandy soilsand in areas of regrowth after fires. The Atlantic Ocean and itscurrent have created a perhumid, moderately cool borealclimate. Forest growth is productive except where the bedrockis exposed. Forestry and agriculture are the major land-orientedactivities. In addition, the natural beauty of the interior andcoastal environment supports a valuable tourist industry.

There are 35 ARNEWS plots in the Atlantic MaritimeEcozone. Species descriptions include white pine, jack pine,red pine, larch/tamarack, black spruce, red spruce, hybridspruce, white spruce, balsam fir, trembling aspen, white birch,yellow birch, black cherry, red maple, and sugar maple.

Eastern White Pine (Pinus strobus L.)There was no mortality of eastern white pine in the

ARNEWS plots in 1993. The average annual mortality ofwhite pine between 1984 and 1993 is 0.9%. The condition ofthe trees was good; most were in the healthiest classes 1 and 2.The condition of white pine has been stable since 1989following an improvement over conditions in the first 3 yearsof ARNEWS assessments. All trees were declining ordeteriorating in the 1984–86 period; gradual improvementoccurred in 1987 and 1988 and 80% or more of the trees havebeen classified healthy since 1990. Foliar damage by insects,including the white pine weevil (Pissodes strobi Peck.), andunidentified flecking on needles were observed at trace levels.

Jack Pine (Pinus banksiana Lamb.) One jack pine tree died representing 1.6% of all jack pine

in the ARNEWS plots in the ecozone. The average annualmortality of jack pine between 1984 and 1993 is 1.8%. Thedead tree was intermediate in the crown and had beendeteriorating since 1991 when the top was broken. The treewas also attacked by sawyer beetle (Monochamus sp.) in 1991.

There was slight deterioration in the overall condition ofjack pine in 1993 shown by an increase in the number of bothdeclining and deteriorating trees. About two thirds were inclasses 3 and 4 and the remainder were in poorer condition.There was considerable insect damage from 1987 to 1990from spider mites, tip borers, gall makers, and the pitch nodulemaker, which all contributed to the declining condition. Manyof the trees had been damaged by a severe storm which causedsome of them to decline and die. Foliar damage by insects,diseases, or abiotic causes was at trace levels in 1993.

Red Pine (Pinus resinosa Ait.) No mortality occurred in 1993, nor has any occurred since

plot establishment in 1984. Tree condition declined from 1984to 1991; since then the number of trees in class 3 increased from35.1% in 1992 to 51.1% in 1993. Many trees had yellowing of


old foliage concentrated in the lower crown. Needle retentionwas 3–4 years for healthy trees and 2–3 years for trees inclasses 5 and 6. Needle reddening and the premature loss ofneedles may be the result of the shallow soils and damage bythe pine rosette mite (Trisetacus gemmavitians Styer). A studyis ongoing to determine the cause of the decline.

Larch/Tamarack (Larix laricina [Du Roi] K. Koch)No trees died in 1993; the average annual mortality

between 1984 and 1993 is 1.0%. No tree has died since 1991.The condition of larch has been deteriorating gradually since1984. Although there is little mortality, increasing numbers ofstressed trees are showing signs of decline and deteriorationwith about half in declining stages, that is, class 4 or greater.European larch canker (Lachnellula willkommii [R. Hartig]Dennis) is affecting many trees mostly in the form of branchcankers and is a factor in the degradation process. Foliardamage by insects, diseases, or abiotic causes was usually attrace levels, and many trees were damaged by the larchcasebearer (Coleophora laricella Hbn).

Black Spruce (Picea mariana [Mill.] B.S.P.)No trees died in 1993. The average annual mortality of

black spruce between 1984 and 1993 is 1.9%. The condition ofblack spruce has improved slightly since 1992 but most trees(93.2%) have some defoliation. Most trees are in classes 3 and4, 44.4% and 40.7%, respectively. There was a gradual dete-rioration in tree condition until 1992 after which it improved.The poor condition of trees before 1988 was caused bydefoliation by the spruce budworm (Choristoneura fumiferanaClem.) Foliar damage by insects, diseases, or abiotic causeswas at trace levels in 1993.

Needle retention was 8–9 years for healthy trees (class 3)and 7–8 years for trees in classes 4–5.

Red Spruce (Picea rubens Sarg.)Four red spruce died in the ARNEWS plots in the Atlantic

Maritime Ecozone in 1993, or 1.3% of the total. One tree waswindthrown and another had the top broken off and wasattacked by a bark weevil (Pissodes sp.). The others had beenseverely damaged by spruce budworm, were suppresssed, andgradually declined.

The condition of red spruce has gradually improved since1991 and about two thirds of the trees are now in the healthiestclasses. There is some regional variation in tree conditionreflecting the intensity of insect outbreaks. In the MontMégantic area in southern Quebec, 38% of the trees changedfrom class 3 to class 4; foliar damage appeared as needleyellowing and reddening in the lower third of the crown.

Foliar damage by insects, diseases, or abiotic causes wasusually at trace levels and there was considerable variation

among plots. Spruce budworm caused light defoliation innorth central New Brunswick, and winter drying was recordedon several plots.

Spruce HybridsThese trees are introgressed hybrids of red spruce and

black spruce and exhibit characteristics of both parents. Notrees died in 1993, and the average annual mortality between1984 and 1993 is 0.9%.

In 1993, two thirds (66%) of the trees were healthy (inclasses 1–3), about a fifth (22.7%) were declining, and 11%were dead. The condition of the spruce hybrids has beengradually changing during the past 7 years; the condition ofsome trees is improving indicating reduced stress, while othersare showing signs of decline and deterioration. This patterncould be the result of competition in the younger stands. Foliardamage by insects, disease, or abiotic causes was at trace lev-els in 1993.

White Spruce (Picea glauca [Moench] Voss) No white spruce died in 1993; the average annual mor-

tality between 1984 and 1993 is 0.5%. The condition of whitespruce has been stable since 1991 and has improved graduallysince 1984. There is little mortality or deterioration, and treesare recovering from spruce budworm damage and becominghealthier. There is little variation in tree health throughout theecozone except where previous budworm damage had beenparticularly severe such as on Cape Breton Island. Foliardamage by insects, diseases, or abiotic causes was at trace lev-els in 1993. Spruce budmoth (Zeiraphera canadensis) dam-aged shoots and spruce needle rust (Chrysomyxa ledicola[Peck] Lagerh.) affected foliage. Needles were retained for6–8 years on healthy trees.

Balsam Fir (Abies balsamea [L.] Mill.)Ten trees died in 1993 in the Atlantic Maritime Ecozone, or

1.9% of the total. Trees were in all four crown classes from dom-inant to suppressed. Three trees had been more or less uprootedin windstorms and subsequently damaged by armillaria root rot(Armillaria mellea) and other diseases. The remainder hadshown previous signs of deterioration and had been damaged byeither armillaria root rot or sawyer beetle (Monochamus sp.) orboth. Natural thinning also caused some mortality.

The largest group of trees were in class 3 (49.6%) and hadless than 25% defoliation. Condition, however, varied widelythroughout the ecozone depending on local occurrences ofspruce budworm outbreaks. There is a steadily increasing treemortality rate as insect-weakened and suppressed trees suc-cumb to secondary organisms or blowdown.

Foliar damage by insects, diseases, or abiotic causes wascommon; spruce budworm caused widespread but not severe


defoliation in northern New Brunswick, and the introducedfalse balsam gall midge (Dasineura balsamicola Lint.) affectedtrees in western Nova Scotia. Foliage browning due to abioticcauses increased over 1992 levels, and needle flecking wasobserved on trees in a plot in Cape Breton. Healthy treesretained their needles for 5–9 years or longer.

Trembling Aspen (Populus tremuloides Michx.)No trembling aspen died in 1993 but several declining and

deteriorating trees were observed and mortality may increase.In 1993, there were trees in every tree condition category:about half of the trees (47.7%) were healthy and a third(33.7%) were declining in class 40 with some branch mortality.

Foliar damage by insects, diseases, or abiotic causes wasat trace levels; poplar serpentine leafminer (Phyllocnistispopuliella Cham.) and a leaf rust (Melampsora abietis-canadensis Ludwig ex Arth.) affected trees. Hypoxylon canker(Hypoxylon mammatum [Wahl.] P. Karsten) was observed fre-quently and some trees have been killed by the disease.

White Birch (Betula papyrifera Marsh.)Four white birch died in 1993, a death rate of 1.9%. Three

trees died from a combination of acid fog and subsequentstress and had been in a deteriorating condition during thepast 4 years. The pollutants are responsible for severe foliagebrowning since at least 1979. The fourth tree died from woundsand decay organisms.

In 1993, fewer than half of the trees (41.2%) were healthyand approximately 40% were declining and had some branchmortality. There were white birch trees in all tree conditionclasses and there was a wide variation among the plots. Mostof the white birch in the Atlantic Maritime Ecozone, apartfrom along the Bay of Fundy, had low levels of branch andtwig dieback. There is no decline in the ecozone generally,only the area influenced by acid fog along the Bay of Fundy.

Foliar damage by insects, diseases, and abiotic causesincreased slightly over 1992 levels. Insect damage levelsincreased slightly from 3% to 5.5% caused by the birch leaf-miner (Fenusa pusilla Lep.) and the birch skeletonizer (Buc-culatrix canadensisella Cham.) The most prominent disease,observed on 7% of the leaves, was septoria leaf spot (Septo-ria sp.), which occurs frequently in association with foliagediscoloration caused by acid fog.

Yellow Birch (Betula alleghaniensis Britton)One tree died in 1993 (1.5% of the total) as a result of

mechanical injury and armillaria root rot. In 1993, about halfof the trees (51.6%) were healthy with some stress and theremainder (45%) were declining and had limited amount ofbranch dieback. The condition of yellow birch has remainedstable since 1991, individual trees changing among tree

condition classes. There has been a gradual decrease in thenumber of vigorous trees over the years, but slightly more thanhalf of the trees have remained healthy since 1988.

Foliar damage by insects, diseases, or abiotic causes wasat trace or light levels. A variety of insects damaged trees, andbirch leafminer and birch casebearer (Coleophora serratella L.)were the most notable. Wind damaged some foliage.

Black Cherry (Prunus serotina Ehrh.) No trees died in 1993. As in previous years, most trees

showed some twig and branch dieback in 25% of the crown.Foliar damage was caused by insects, and leaf spots werepresent on all trees at trace or light levels. Black knot (Apiospo-rina morbosa [Schwein.: Fr.] v. Arx) occurred on crowns andoccasionally on stems.

Red Maple (Acer rubrum L.)Two trees died in 1993, 1.4% of the trees in this ecozone.

These trees were both suppressed trees in poor condition forthe past 3 years. One of the trees was killed by armillaria rootrot and the other had several unidentified stem cankers.

The condition of tree crowns was generally poor. Twothirds were in class 40 and had up to 15% twig and branchmortality. Several insects and diseases were present on thetrees when the program was established and they continue toaffect the trees. Drought in the sample area may have affectedthe trees, and exposure of residual hardwoods after loggingmay also have further stressed the trees. Foliage was damagedby gall mites, anthracnose (Aureobasidium apocryptum [Ell. &Ev.] Herm.-Nij.), and leaf spot fungus (Phleospora aceris [Lib.]Sacc. and Phyllosticta minima [Berk. & Curt.] Underwood &Earle). Some damage was also caused by wind.

Sugar Maple (Acer saccharum Marsh.)No trees died in 1993. Most of the trees were in classes

30 and 40, indicating some stress; 54.5% of the trees were inclass 40, that is, twig and branch mortality occurred in up to15% of the crown.

Foliar damage by insects, diseases, or abiotic causesoccurred at trace or light levels on sugar maple in the AtlanticMaritime Ecozone. Some trees on one plot were damaged bymites (Phyllocoptes sp.), and leaf spot fungus occurred occa-sionally in northwestern New Brunswick. Leaf spot and anthrac-nose was observed on trees in Quebec.

In summary, in the Atlantic Maritime Ecozone, foliardamage was widespread on trees but usually at trace, light, ormoderate levels; tree health was not seriously affected.Symptoms of air pollution damage were observed particularlyon white birch near the Bay of Fundy. Needle flecking occurredoccasionally on conifers. Levels of mortality were within thenormal range for these forests and the causes were identified.


Mixedwood Plains

This ecozone covers the Lower Great Lakes–St. LawrenceValley area including the southern parts of Ontario and Quebecand is bisected by the Canadian Shield. Underlain by carbonaterich Paleozoic bedrock, this nearly level to rolling plain isdominated by a variety of deep, moraine, marine, and lacustrinedeposits. In the northern portion, the predominant soils arepodzols, luvisols, and brunisols. The forest in the northernportion is mixed coniferous–deciduous, dominated by whiteand red pine, eastern hemlock, oak, ash, maple, and birch. Asmall part of the deciduous forest, widespread in the easternUnited States, continues northward into southeastern Ontario.Previously abundant species include sugar maple, beech, whiteelm, basswood, and red and white oaks. Heavily forested at onetime, very little of the original forest remains today especially inthe southern portions. Much of the area is heavily settled, andthe forest vegetation is now in farm woodlots, hedgerows, andremnant stands. The zone has a humid, mild, mesic continentalclimate typified by warm summers and cool winters. Theweather is highly changeable in this region because it lies withinone of the major storm tracks of North America.

This ecozone spans four of the Great Lakes and containsimportant aquatic ecosystems, shipping corridors, and recre-ation areas. The combination of agricultural soils, gentletopography, and relatively warm summer climate has causedthis unit to be one of the most intensively used and highlypopulated.

There are 18 ARNEWS plots in the Mixedwood PlainsEcozone. Species descriptions include eastern white pine, whitespruce, red oak, and sugar maple. Frequently there is only onespecies per plot, so trends must be interpreted cautiously.

Eastern White Pine (Pinus strobus L.)No white pines died in this ecozone in 1993. Overall tree

condition has been constant for the past 5 years; about onethird of the trees had no damage at all. About half the trees(56%) are in class 4, that is from 25 to 50% defoliation.Many trees have been damaged by the white pine blister rust(Cronartium ribicola J.C.Fischer). No other damage wasobserved.

White Spruce (Picea glauca [Moench] Voss)Three trees died in 1993, or 5.2% of the total. All trees

were intermediate to suppressed and had been defoliated bythe eastern spruce budworm (Choristoneura fumiferana Clem.)from 1989 to 1991, resulting in poor crown condition. Overall,the condition of the crowns declined in 1993 compared with1992. In 1993, 96.6% of trees were in class 3, that is, the totaldefoliation was up to 25%. Damage to crowns was caused by theeastern spruce budworm.

Red Oak (Quercus rubra L.)No trees died in 1993. There has been little mortality

since 1984 among red oaks. Most of the trees have at leastsome dead branches in the crown. A variety of insects affectedtree crowns in 1993. Damage was caused by skeletonizinginsects, generally the oak skeletonizer (Bucculatrix ainsliellaMurt.), and pear thrips (Taneothrips inconsequens Uzel).Damage was at trace or light levels and so probably had littleeffect on tree health.

A variety of diseases affected the foliage also at trace orlight levels, including leaf blister (Taphrina caerulescens[Desm. & Mont.] Tul.) and anthracnose (Discula umbrinella[Berk. & Broome] Morelet). Twigs were diseased by Doth-iorella quercina (Cooke & Ellis) Sacc., Dothiorella advena(Cooke & Ellis) Sacc., Pseudovalsa longipes (Tul.) Sacc., andsome Cytospora sp. Twig dieback was caused by D. advena S.Some unknown abiotic factor(s) are causing a decline in thehealth of oaks in southern Quebec. Investigations of the pos-sible causes continue.

Sugar Maple (Acer saccharum Marsh.)Three trees died in 1993, 3.2% of the total in the ecozone.

These were intermediate or suppressed trees and had beenattacked by armillaria root rot. The condition of sugar maplecrowns was good and has changed little over the past 5 years.In 1993, 13.5% of the trees had no damage at all, 42.3% hadtwigs dead but no dead branches, and an additional 36.9% ofthe trees had twig and branch damage but less than 25% of thecrown affected.

Damage at low levels was caused by the sugar mapleborer (Glycobius speciosus Say) and pear thrips. Stem decaywas observed occasionally and foliar damage was caused byleaf spot and anthracnose.

In summary, in the Mixedwood Plains Ecozone, treemortality was higher than normal for two species, white spruceand sugar maple. Causes were typical of these forests. Damageto crowns occurred from leaf skeletonizers, leaf defoliators,and leaf spots. No symptoms of air pollution damage wereobserved on any trees.

Boreal Shield

The Boreal Shield Ecozone extends from northernSaskatchewan east to Newfoundland, passing north of LakeWinnipeg, the Great Lakes, and the St. Lawrence River. Thezone is dominated by broadly rolling uplands and lowlands.Precambrian granitic bedrock outcrops interspersed with ridgedto hummocky, discontinuous veneers and blankets of glacialmoraine, fluvio-glacial deposits, and colluvium are character-istic of its surface. Soils range from humo-ferric podzols in thesouth to brunisols in the north. The zone generally supports


closed stands of conifers, largely white spruce and black spruce,balsam fir, and tamarack. Toward the south, there are morebroadleaf trees: trembling aspen, balsam poplar, and whitebirch. Conifers common in the south include white pine, redpine, and jack pine. Throughout the contrasting areas of exposedbedrock, this mosaic of soils and non-soils tends to be coveredwith a range of communities dominated by lichens, shrubs, andforbs. Small to medium-sized lakes are common. Climate in theecozone ranges from humid, cryoboreal in the northwestern partto perhumid, moderately cool, boreal climate in the east. Its con-tinental climate is modified by maritime conditions in its coastalregions to the east and by cold arctic air masses from the north.

There are 57 plots in this ecozone and the species descrip-tions include eastern white pine, jack pine, tamarack, blackspruce, white spruce, red spruce, Norway spruce, balsam fir,trembling aspen, white birch, beech, and red maple.

Eastern White Pine (Pinus strobus L.)One tree died in 1993; mortality since ARNEWS was

established has been less than 1% annually. Tree condition isvariable throughout the ecozone. Crowns are in poor conditionin some areas and have been deteriorating in recent years. In1992, 66.7% of trees were in class 4, but in 1993, 58.8% werein class 5 and 29.4% in class 4. The missing foliage is a resultof damage by various defoliating insects. White pine blisterrust has persisted in some areas for several years generallyaffecting younger trees. Needle retention is lower than normalbut no signs of pollution damage are present.

Jack Pine (Pinus banksiana Lamb.)No mortality occurred in 1993; mortality since the plots

were established is 0.3% annually. Tree condition is generallygood overall; 74.7% were in classes 1–3. There was some dete-rioration during the past 5 years; 88.8% were in classes 1–3 in1992. Tree condition was best in Manitoba and Ontario, andcrown damage was highest in Quebec. In the western part of theecozone, the most prevalent and damaging pests were westerngall rust (Endocronartium harknessii [J.P. Moore] Y. Hiratsuka)and red squirrels (Tamiasciurus hudsonicus). Trees were alsodamaged by the larvae of the olethreutid moth (Rhyacionia sp.)

In some areas in Ontario, tree condition has improvedsince 1989, 90% of dominant/codominant trees having noapparent damage. In the Manitoba portion of the Boreal ShieldEcozone, about 97% of the trees were in the healthiest classes.Needle retention was normal.

Tamarack (Larix laricina [Du Roi] K. Koch)No mortality occurred in 1993. Trees are generally healthy

and have been damaged at only trace levels. The most wide-spread damage was caused by the larch sawfly (Pristiphoraerichsonii Htg.).

Black Spruce (Picea mariana [Mill.] B.S.P.)In 1993, three trees (0.5%) died in plots in the Boreal

Shield Ecozone. Cause of death originated with defoliation inprevious years by the eastern spruce budworm, subsequentattack by the spruce beetle (Dendroctonus rufipennis Kby.),and infection by armillaria root rot.

Tree condition was generally good in 1993; 45.8% of treeswere in classes 1 and 2 and 33.5% in class 3. However, this is adecrease from previous years when about 70% were in classes 1and 2. Tree condition was best in Newfoundland where over80% were in the healthiest classes (1–3). Crown damage wasmore prevalent in Quebec where over half the trees were dam-aged by defoliating insects and rust damage on needles. In someareas, crown condition improved following a reduction in sprucebudworm defoliation. Evidence of past defoliation by sprucebudworm was common in Ontario plots. Needle retention was6–9 years and the healthier trees retained needles longer.

White Spruce (Picea glauca [Moench] Voss)Two trees died in 1993 from the combined effects of sup-

pression, defoliation by the eastern spruce budworm, barkbeetles, sawyer beetle (Monochamus sp.), and needlecastdiseases.

Tree condition overall was good; 74.8% were in classes 1and 2, that is, less than 25% defoliation. Tree condition wasbest in Newfoundland where trees had recovered from pastinfestations of the spruce budworm, and 86% of trees had nodefoliation. Damage was at higher levels elsewhere because ofdefoliation caused by eastern spruce budworm. Trace levels ofEuropean spruce sawfly (Gilpinia hercyniae Htg.) damageoccurred on current foliage.

Red Spruce (Picea rubens Sarg.)Red spruce is a common species only in the eastern part

of the ecozone in Quebec and eastern Ontario. Mortality of redspruce in 1993 was 0.5%; two trees died from competition anddamage by armillaria root rot. Most trees are in crown condi-tion classes 3–4, and up to 50% of the crown was defoliatedon 78.4% of the trees. This is about the same level as the last5 years. Defoliation was caused primarily by the easternspruce budworm.

Norway Spruce (Picea abies [L.] Karst.)Norway spruce is an exotic conifer commonly planted in

reforestation programs in central Canada. It is represented inone plot in ARNEWS. Two dominant trees died in 1993. Theyhad been in a deteriorating condition for several years andwere damaged by porcupines (Erethizon dorsatum L.) in 1993.Crown condition was good; 87% of the trees were in thehealthy classes. There were trace levels of crown damage fromseveral unidentified pests.


Balsam Fir (Abies balsamea [L.] Mill.)During 1993, five balsam fir trees died or 1.8% of the total.

One tree died from windthrow; two others from armillaria rootrot and secondary insects; and one from a combination ofeastern spruce budworm, sawyer beetle, and competition. Theother tree died suddenly after all foliage turned red during1 year; this is known as Stillwell’s syndrome.

Overall tree condition in balsam fir was good; 88.3% ofthe trees were in classes 1–3. Trees in Newfoundland have beendefoliated in two successive years by balsam gall midge (Para-diplosis tumifex Gagné), and the hemlock looper (Lambdinafiscellaria fiscellaria Gn.) defoliated many trees. Infestationby the balsam woolly adelgid (Adelges piceae [Ratz.]) increasedin 1993, also influencing tree condition. Fir broom rust (Mel-ampsorella caryophyllacearum Schröter) infected 24% oftrees in one plot.

Some intermediate trees showed some decline symptomsand were in classes 4 or 5. Light damage caused by winterdrying affected 11% of balsam fir in one plot in Newfound-land; this was the only incidence of abiotic damage on balsamfir in 1993.

In some areas, particularly in Ontario, tree conditionimproved slightly as a result of a reduction in the eastern sprucebudworm infestation. Crown condition is good in Quebec;80% of the trees are in class 3. Balsam fir had been subjectedto moderate to severe levels of budworm defoliation since1988 resulting in the deterioration in crown condition, but thebudworm defoliation is reduced in 1993 compared withprevious years.

Needle retention was good, 8–9 years on the trees withless damage and 5–6 years on more damaged trees.

Trembling Aspen (Populus tremuloides Michx.)Six trees died in 1993 or 2.5% of the total. This is slightly

above the rate considered normal for forest species, but likebalsam fir, trembling aspen has many stress factors affecting itand is a short-lived species. Three trees died from infection bystem cankers combined with attack by armillaria root rot, onedied from windstorm damage (broken stem), and the othersdied from physical damage.

Overall tree condition was good for a species attractiveto so many insects and diseases. Most trees (66%) were in thehealthiest classes and 25.5% were in class 4. Most trees hadsome foliar damage and about a third had trace levels of foliardamage caused by diseases. Damage was caused by largeaspen tortrix (Choristoneura conflictana [Wlk.]), forest tentcaterpillar (Malacosoma disstria Hbn.), and leaf beetles(Chrysomela sp.). Decay caused by false tinder conk (Phelli-nus tremulae [Bond.] Bond. & Boriss.) and poplar peniophora(Peniophora polygonia (Pers.:Fr.) Bourd & Galz.) occurredfrequently. Stem cankers were common.

White Birch (Betula papyrifera Marsh.)Mortality in 1993 was 1.7%. Five trees died from natural

causes including suppression, attack by armillaria root rot, andin one instance, damage from the bronze birch borer (Agrilusanxius Gory).

Overall tree condition of birches was good. About twothirds of the trees (64.3%) are in the healthiest classes, indi-cating low levels of damage to twigs and branches. This hasbeen caused by various defoliating insects, including birch case-bearer (Coleophora serratella [L.]), and stress from competi-tion resulting in numbers of dead branches.

American Beech (Fagus grandifolia Ehrh.)No trees died in the ecozone in 1993; some older dead

trees are present in or near the plots caused by chronicinfection by the introduced beech bark disease (Nectriacoccinea var. faginata Wats. and Ayers) and beech scale (Cryp-tococcus fagisuga Lind.).

Most trees are healthy but nearly all crown have sometwig or branch dieback, over 93% in the Quebec part of theecozone. Tree foliage was damaged by insects, diseases, andabiotic factors, usually at light or trace levels. Leaf spots wereobserved occasionally on trees in Quebec.

Red Maple (Acer rubrum L.)No mortality occurred in 1993 and tree condition

improved. Overall tree condition has deteriorated steadily since1989 caused by drought-induced decline, physical damage,and associated decay; 1993 is the first year when no furtherdeterioration occurred. Defoliation by insects has been at traceto light levels since 1989 and is not a major factor in the decline.Leaf diseases such as tar spot occur at trace levels.

In summary, mortality levels in the Boreal Shield Ecozonewere within normal levels. Tree health was affected by avariety of insects, diseases, and occasionally by abiotic factors.The degree of tree health varies among species. Balsam fir,white birch, and trembling aspen were often severely damagedby defoliating insects and so were under some stress. Suchdamage tends to be cyclical and tree recovery can be expected.These insects alter tree health predisposing trees to attack bysecondary organisms which also occurred frequently. Nosymptoms of damage by air pollution were observed on treesin the Boreal Shield Ecozone.

Boreal Plains

The Boreal Plains Ecozone extends as a wide band fromthe Peace River country of British Columbia in the northwestto the southeastern corner of Manitoba. This level to gentlyrolling plain is underlain by cretaceous shales and consists ofhummocky to kettled glacial moraine and lacustrine deposits.


The soils are largely luvisols. These grade southwards intoblack chernozems and northwards into brunisols and organics.

White spruce and black spruce, jack pine, lodgepole pine,and tamarack are the main conifer species. Broadleaf trees,particularly trembling aspen, are most numerous in the transi-tional section leading to the prairie grasslands. Other hardwoodscommon in the ecozone are white birch, trembling aspen, andbalsam poplar. Black spruce and tamarack dominate the morenortherly parts of the ecozone. The subhumid, moderatelycryoboreal climate is typified by cold winters and moderatelywarm summers. This ecozone is strongly influenced by conti-nental climatic conditions. There are 12 plots in the BorealPlains Ecozone. Forest health results are described for jack pine,lodgepole pine, black spruce, white spruce, and tremblingaspen.

Jack Pine (Pinus banksiana Lamb.)In 1993, mortality was 4.7%, a result of two trees dying

that had been declining for the past 2 years and had suc-cumbed to armillaria root rot. Mortality since the plot wasestablished is 1.4% annually.

Tree condition has improved from 1992 and 85% of thejack pine are in the healthiest classes. In addition to armillariaroot rot, lodgepole pine dwarf mistletoe (Arceuthobium ameri-canum Nutt. ex. Engelm.) and western gall rust (Endocronar-tium harknessii [J.P. Moore] Y. Hirats.) caused minor damageto jack pine. In previous years, jack pine budworm (Choris-toneura pinus pinus Free.) had damaged trees but the incidenceof this pest is declining. Needle retention is normal.

Lodgepole Pine (Pinus contorta var. latifolia Engelm.)Two trees died in the plots in 1993 or 1.0% of the total.

Annual mortality is 1.5%. Trees died from infection by atro-pellis canker (Atropellis piniphila [Weir] Lohman & Cash) andwestern gall rust. Atropellis canker is the principal agentcausing tree decline.

Some change in tree condition occurred in 1993. Trees inthe healthier classes (1–3) comprised 87.7% in 1993 comparedwith 91.6% in 1992. In 1993, 7.4% of trees were in classes 4–6,that is, more than 25% defoliated.

Light to moderate foliar discoloration was caused by aneedle cast (Lophodermella concolor [Dearn.] Darker) and anassociated hyperparasite (Hendersonia pinicola Wehmeyer).This is part of a widespread occurrence of pine needle cast thatoccurred over more than 193 000 ha in western Canada in1993. Needle retention has been normal.

Black Spruce (Picea mariana [Mill.] B.S.P.)No mortality occurred in 1993; mortality since plot estab-

lishment is 1.1% annually. Most trees (92.3%) were in thehealthiest classes. The only pest found on black spruce was

large-spored spruce–Labrador tea rust (Chrysomyxa ledicolaLagerh.). The rust was causing minor damage to black sprucein Manitoba in Duck Mountain Provincial Park. Needleretention was normal.

White Spruce (Picea glauca [Moench] Voss)No mortality occurred in 1993 and mortality has been

0.6% annually. Trees were generally healthy in 1993; 92%of the trees were in the healthiest classes. Tree conditionimproved from 1992 because of the reduction in damage byinsects and diseases. In eastern Saskatchewan, trees were dam-aged by an outbreak of the eastern spruce budworm that haddefoliated many trees at light to moderate levels. In other areas,pests damaging trees included the spruce gall midge (Mayeti-ola piceae [Felt]), the pale spruce gall adelgid (Adelges laricisVallot), and spruce broom rust (yellow witches’-broom)(Chrysomyxa arctostaphyli Diet.). Needle retention has beennormal.

Trembling Aspen (Populus tremuloides Michx.)No mortality occurred in 1993 and annual mortality has

been 0.9% in the ARNEWS plots. Tree health declined in 1993from 1992 primarily because of defoliation by the large aspentortrix which caused moderate to severe defoliation throughoutlarge parts of the ecozone. Other significant pests observedwere false tinder conk and poplar peniophora. Overall, 76.6%of the trees were in the healthiest classes, 10–30. In 1992,97.2% were in class 10, indicating some deterioration sincethen. Tree condition has fluctuated widely over the past5 years coincident with insect infestations and local frostoccurrences.

In summary, mortality in the Boreal Plains Ecozone waswithin the normal range for these unmanaged stands and thetrees were affected by a variety of known pests and diseases.No symptoms of pollution damage were observed.

Taiga Plains

The Taiga Plains are mainly located in the southwest-erly corner of the Northwest Territories, northeastern BritishColumbia, and northern Alberta. This level to gently rollingplain is underlain by cretaceous shale and covered with organicdeposits, undulating to hummocky glacial moraine, and lacus-trine deposits. A large portion of the area is underlain by per-mafrost, and this acts to perch the surface waters and promote aregional overland seepage system. When combined with low-angle slopes, it creates a landscape that is seasonally water-logged over large areas. Patterned ground features are common.Its widespread permafrost and poor drainage create favorableconditions for cryosolic, gleysolic, and organic soils. Arctictundra meadows and wetland plant associations are common.


Dwarf birch, labrador tea, willows, bearberry, mosses, andsedges are dominant species. Upland and foothills areas andsoutherly locales tend to be better drained, warmer, and supportmixedwood forests characterized by jack pine, lodgepole pine,tamarack, white spruce, black spruce, trembling aspen, balsampoplar, and white birch. Its subhumid, subarctic climate ismarked by cool summers and long, very cold winters. Coldarctic air influences the area for most of the year. Some forestry,mining, and oil/gas activities are also carried out.

This ecozone is represented by two plots in ARNEWS,consequently conclusions are based both on ARNEWS resultsand other parts of the FIDS network.

White Spruce (Picea glauca [Moench] Voss)Data was collected in this ecozone for the first time in

1993. White spruce were healthy; 80.0% of the trees were inclass 1–2 and the remainder in class 3. The only pest presentwas spruce gall midge which damaged 13% of the whitespruce. Needle retention was normal.

Trembling Aspen (Populus tremuloides Michx.)The 1993 field season was the first in which condition data

were collected. Crown condition was good; 95.0% of the aspenwere in classes 10–30. The only important organism in the twoplots was the false tinder conk which infected 4% of the trees.

In summary, based on the limited data available for thisecozone, tree health is good, and crowns were affected by fewdamaging organisms. No symptoms resembling those causedby air pollution were observed. Results are consistent withthose from other surveys.

Montane Cordillera

Most of southern British Columbia and a portion ofsouthwestern Alberta are contained within this ecozone. It is arugged, mountainous unit which rings several major interiorplains. The plains are more extensive in the north and extendto the intermountain valleys towards the south. The plainsconsist of glacial moraine and some fluvial and lacustrinedeposits, while the mountains consist largely of colluvium andoutcrops.

The most common soil types are luvisols and brunisols;podzols occurr throughout the mountainous terrain in the east.The soils of the lower valley floor of the plains to the south areoften chernozems and support grasslands. These grade intodesert-like environments towards the Canada–United Statesborder. Ecoclimates are diverse; the alpine environment athigher elevations contains various herb, lichen, and shrubassociations, while the subalpine environment has tree speciessuch as lodgepole pine, alpine fir, and Engelmann spruce. Thevegetation of the mountainous slopes and rolling plains

contains the three species groups lodgepole pine, Engelmannspruce, and alpine fir; in the north and central parts of theecozone are ponderosa pine, interior Douglas-fir, lodgepolepine, and trembling aspen; and in the southeast are westernhemlock, western red cedar, interior Douglas-fir, and westernwhite pine.

The climate ranges from subarid, mild mesic in southernlower valleys to humid, cold subarctic in the north and higherelevations. The ecozone is characterized by moderately long,cold winters and short, warm summers.

Commercial forest operations have been established inmany parts of the Montane Cordillera, particularly in the north-ern interior sections. In the eastern Rockies and ColumbiaMountains, national and provincial parks have been estab-lished for recreational use or as reserves for wildlife habitat.

There are 12 ARNEWS plots in the ecozone and speciesdescriptions include lodgepole pine, ponderosa pine, Engel-mann spruce, white spruce, western hemlock, Douglas-fir inte-rior variety, alpine fir, western red cedar, and trembling aspen.

Lodgepole Pine (Pinus contorta var. latifolia Engelm.)One tree died in 1993 (0.6% of the total) after having been

damaged for many years by atropellis canker. The diseaseaffects the health of lodgepole pine and is present on manytrees. The crowns of lodgepole pine are in good condition andover 94% of the trees have no defoliation. Some foliar loss andchlorotic foliage were caused by summer drought stress. Lightto moderate foliar discoloration on some trees was caused by aneedle cast (Lophodermella concolor [Dearn.] Darker) and anassociated hyperparasite (Hendersonia pinicola Wehmeyer).Western gall rust infected stems and branches, and the sequoiapitch moth (Synanthedon sequoiae Hy. Edwards) also dam-aged some trees. The pitch moth is causing canker-like depres-sions on the infested pine stems; these infested trees are proneto stem breakage at the point of infestation. Needle retentionduring the last few years has been normal.

Ponderosa Pine (Pinus ponderosa Laws.)This species was first assessed by ARNEWS in 1993.

Most trees (80%) were healthy and had a full complement ofnormal foliage. About 16% of the trees were in class 2 and hadsome current defoliation caused by a weevil (Pachyrhinus[=Scythropus] californicus Horn). Some foliage loss was alsocaused by squirrels. Trace to light foliar discoloration on 78%of the trees at one plot was caused by a needle cast (Leptomel-anconium cinereum [Dearn]. Morgan-Jones).

Engelmann Spruce (Picea engelmannii Parry)No trees died in 1993. All trees had less than 25% of

the current foliage damaged by a spruce budmoth (Zeira-phera spp.).


White Spruce (Picea glauca [Moench] Voss)One tree (1.7%) died in 1993 from suppression and sec-

ondary attack from bark beetles (Dryocoetes affaber Manner-heim). Nearly all trees (89.7%) were undamaged; the remainderwere in poor condition from storm damage before 1993, androot and stem rot.

Western Hemlock (Tsuga heterophylla [Raf.] Sarg.)No trees died in 1993 in the ARNEWS network. Mortality

since plot establishment in 1985 has been 6%, caused by naturalthinning and storm damage. Most trees (76%) were healthy witha full complement of normal foliage. Trees were defoliated bythe western hemlock looper (Lambdina fiscellaria lugubrosaHulst). Most other trees that had foliar loss were suppressedunderstory trees in dense, closed canopies on coastal plots. A fewtrees had part of the crown damaged by storms. About 10% oftrees had trace levels of foliar discoloration attributed to naturalshading and competition in closed canopy stands.

Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco)The interior variety of Douglas-fir is a prominent species

in this ecozone. No trees have died since plot establishment.About two thirds (67%) of these trees were defoliated by thewestern spruce budworm (Choristoneura occidentalis Free.)There has been no mortality yet, but trees greater than 90%defoliated will probably die. This is the fourth consecutiveyear that trees have been defoliated.

Alpine Fir (Abies lasiocarpa [Hook.] Nutt.)No trees died in 1993; mortality to date has been due to

natural suppression in closed stands. Most trees (84%) werehealthy and had a full complement of normal foliage. Foliarloss was attributed to natural shading.

Western Red Cedar (Thuja plicata Donn)No trees died in 1993. About half of the trees (56%) were

healthy and had a full complement of normal foliage. Theremaining trees were defoliated to varying degrees by the west-ern hemlock looper. Some trees lost foliage from crown shadingin dense unmanaged stands and from windstorms.

Trembling Aspen (Populus tremuloides Michx.)One tree died in 1993, 1.0% of the total in the system. The

cause of death was stem cankers and wounding from previousstorms. Most trees were healthy and had a full complement ofnormal foliage. No foliar discoloration was observed.

In summary, in the Montane Cordillera Ecozone, treemortality was at normal levels and caused by known factors.Crowns were damaged by insects, shading in dense stands, andstorms. No symptoms resembling those caused by air pollutionwere observed.

Boreal Cordillera

This ecozone is located in the midsection of the CanadianRocky Mountain system. It covers sections of northern BritishColumbia and the southern Yukon Territory. The zone is char-acterized by mountain ranges that contain numerous highpeaks, extensive plateaux, and intermountain plains. Theseplains have been modified by glaciation, erosion, solifluction,and aeolian and volcanic ash deposition. Glacial drift, collu-vium, and outcrops are the main surface materials. Perenniallyfrozen ground (permafrost) and associated landscape featurestend to be widespread in the more northerly areas, and athigher elevations soils are cryosols. In the warmer lower eleva-tions in the southern half, brunisols, podzols, and luvisols arecommon. The climate ranges from humid to subhumid, verycold subarctic to cryoboreal. It is marked by long, cold wintersand short, warm summers and modified by vertical zonationand aspect. The Pacific Maritime influence is responsible formost of the precipitation that occurs in the autumn.

The vegetation consists of closed and open canopies overmuch of the plateaux and valleys. Tree species include lodge-pole pine, white spruce, black spruce, alpine fir, white birch,trembling aspen, and balsam poplar. In the northwest, thestands are generally open, and lodgepole pine and alpine fir areusually absent. Alpine tundra is prevalent at higher elevations,with sedge-dominated meadows and lichen-colonized rockfields being common. The forest, mineral, and large river sys-tem resources have fostered forestry, mining, and hydroelectricdevelopments. Tourism and recreation activities are importanteconomically. There is one ARNEWS plot in the ecozone.

Lodgepole Pine (Pinus contorta Dougl. var. latifolia Engelm.)No trees died since the plot was established in 1992. Over

80% of the trees had no foliar damage and most of the remain-der were in classes 3 and 4. Foliar loss was caused by summerdrought stress. Light to moderate foliar discoloration on treesin classes 3 and 4 was caused by a needle cast (Lophodermellaconcolor [Dearn.] Darker) and an associated hyperparasite(Hendersonia pinicola Wehmeyer). No other organisms wereobserved on the trees. No symptoms resembling those causedby air pollution were observed in the plot. Results are con-sistent with those from other surveys.

Pacific Maritime

This ecozone ranges along the Pacific Coast to the Alaskapanhandle. Mountainous topography dominates, cut throughby numerous fjords and glacial valleys and bordered by coastalplains along the ocean margin. Igneous and sedimentary rocksunderlie most of the area. Colluvium and glacial deposits arethe main surface materials. The soils are largely podzols, and


brunisols and folisols are common. The western coastal forestis composed mostly of western red cedar, western hemlock,Douglas-fir, mountain hemlock, amabilis fir, Sitka spruce, yel-low cedar, and alder. Douglas-fir is confined largely to the south;in the north, amabilis fir is more common. Mountain hemlockoccurs on the higher elevations.

The ecozone ranges from maritime-moderated, perhumid,mild mesic coastal climate to subhumid, cool boreal to mod-erately cool cryoboreal in the mountains. The annual precip-itation ranges from 600 mm in the lower Georgia Strait to3000 mm over the rest of the zone. There is little variationamong the mean monthly temperatures.

Much of the land is commercial forest. The lowlands ofthe Fraser Valley and the southeastern tip of Vancouver Islandcontain mainly agricultural soils and urban lands.

There are 13 ARNEWS plots in this ecozone and speciesdescriptions include Sitka spruce, western hemlock, Douglas-fir, amabilis fir, and western red cedar.

Sitka Spruce (Picea sitchensis [Bong.] Carr.)No mortality occurred in 1993. About three quarters of the

trees (74%) were healthy and had a full complement ofnormal, healthy foliage. Trees that had foliar damage weremainly understory, stressed trees. Some trees had trace to lightlevels of discoloration caused by a needle rust (Chrysomyxaspp.)

Western Hemlock (Tsuga heterophylla [Raf.] Sarg.)Two trees died in 1993, both as a result of storm damage.

Both trees had also been understory trees and had beensuppressed. There has been 6% total mortality of westernhemlock since the plots were established, averaging 0.7%annually. Nearly all trees (93.2%) were in the healthiestclasses (1–3). Most other trees that had foliar loss were sup-pressed, understory trees in dense, closed canopy, coastalplots and a few had a portion of the live crown broken-offby storm damage. About 10% of the assessed trees hadtrace levels of foliar discoloration, mainly chlorotic, olderfoliage in the lower crown, attributed to natural shading andcompetition.

Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco)Six trees died in 1993 in the ARNEWS network, or 1.0%

of the total. Five of the dead trees were suppressed, understorytrees that died from competition and shading, the other treedied as a result of storm damage. Nearly all trees (91.1%) hadno defoliation; another 3.4% had up to 25% defoliation andfoliar discoloration. This foliar damage was caused by naturalshading and competition in closed canopy stands and Swissneedle cast (Phaeocryptopus gaeumannii [Rhode] Petrack)caused foliar discoloration in central Vancouver Island.

Amabilis Fir (Abies amabilis [Dougl.] Forbes)Two amabilis fir died in 1993, 1.9% of the total. Mortality

was caused by shading and suppression in the closed stands.Most trees (80%) had a full complement of foliage. Most of thetrees that had some level of foliar loss were suppressed, under-story trees; two are dying and had pronounced discolored,reddish brown foliage. Nearly all trees had some foliardiscoloration (average 10%), but it was mainly chlorotic, withsome reddish brown older foliage in the shaded lower crown.A needle blight (Phaeocryptopus nudus [Peck] Petrak) causedsome discoloration.

Western Red Cedar (Thuja plicata Donn)No trees died in the ARNEWS network in 1993. About half

the trees (56%) were healthy and had a full complement ofnormal foliage. The remainder had damage caused by shadingof the understory, suppressed trees. Trace levels of foliar dis-coloration occurred on a few trees in two plots caused by nat-ural shading and lower crown dieback in closed canopy stands.

In summary, trees in the Pacific Maritime Ecozone had lowmortality rates, caused by suppression and shading for theunderstory trees and some trees killed by storm damage. Somefoliage damage was caused by defoliating insects, needle casts,blight fungi, and shading of understory trees. No symptoms ofpollution damage, such as needle flecking, were observed.

Health of Canada’s Model Forests

The goal of the Model Forest Program is to develop a co-operative system to ensure that ecologically sound, econo-mically viable, and socially acceptable decisions are madeabout how forests should be managed. Several factors areimportant in making the model forests concept work:ecological processes, forest practices, analysis of socio-economic trends, and communications. Knowledge of the stateof the health of these forests is necessary for the sustainablemanagement of the model forests. Model forests are repre-sented within the ARNEWS network, and there are additionalplots in nearby forests representing the same species and/orsimilar forest types. The evaluation of forest health is based onthe data from ARNEWS plots in the model forests augmentedby the results of other surveys by the FIDS organization.

Western Newfoundland Model Forest

The Western Newfoundland Model Forest covers707 000 ha in the Boreal Shield Ecozone. The model forest isa major timber supply area for two newsprint mills and con-tains large populations of moose, caribou, and black bear, anda variety of small fur bearers including the only remaining


population of Newfoundland pine marten (Martes americana).Recreation is an important part of the model forest becauseaccess to and use of the forest is perceived by Newfoundlandersas an inherent right.

Traditional forest management within the model forestarea has concentrated on timber production rather than otherresource values. In an attempt to redress this, a multidisci-plinary project has been initiated to develop a managementstrategy including timber harvesting, wildlife habitat, recre-ation, and the preservation of water quality.

Forests in this area have been repeatedly damaged byinsect outbreaks, particularly the eastern spruce budworm andthe hemlock looper. Although the forests are boreal, they haveseldom been affected by wildfire because of the high rainfalland humidity.

There are three ARNEWS plots in the model forest andthe major species assessed are balsam fir, white spruce, andyellow birch. There was no mortality in these plots in 1993.All balsam fir are in the healthiest three crown conditionclasses. Light levels of defoliation were observed on 38% ofthe trees caused by the balsam gall midge. Similarly, nearly allthe white spruce are healthy with trace levels of defoliation onabout 20% of the trees. There is some damage on yellow birchcaused by the birch casebearer.

Fundy Model Forest

The Fundy Model Forest in the Atlantic Maritime Eco-zone has a direct impact on a large portion of the population ofNew Brunswick. The three largest urban centers are near the400 000-ha model forest, and many communities that dependdirectly on forest lands are within its boundaries. These com-munities have a keen interest in how the forest is managed andthey bring a diversity of values and visions of the forest indefining forest management goals.

The forest has a mixture of uses: commercial, private, andrecreational. The forest also has a long history of insect dam-age, and defoliation by the eastern spruce budworm is the mostprominent. Red spruce, white birch, and red maple aredescribed from the two ARNEWS plots in the model forest.

No red spruce trees died in 1993. Trees were in goodcondition and 86% were in the healthiest classes (1–3). Foliardamage consisted of reddening of needles due to winterdrying. This condition was extensive and severe near coastalareas. No insect damage was observed.

White birch has been extensively damaged by acid fog since1979. Most trees were in poor condition in 1993; nearly 44% ofthe trees are dead, 15% are deteriorating (classes 50–65), and23% are declining. Only 18% of the trees are healthy. Three treesdied on the plot in 1993, and all were codominant trees indeteriorating condition during the past 4 years. Foliar damage by

insects, diseases, and abiotic conditions was light and did notexceed 10% in any category. Leaf browning, associated with acidfog, accompanied by the leaf spot fungus (Septoria betulae [Lib.]West) was the most common damaging agent observed. This isthe only incidence of forest decline caused by acid rain observedby ARNEWS to date.

Red maple trees were generally in poor condition. Fewerthan one third of the trees (30%) were in the healthy classes(10–35), half were declining (classes 40–45), and over a fifth(22%) were dead. The cause of death is unknown because thetrees were dead at the time of plot establishment in 1993. Foliardamage was light and was caused by gall mites (Eriophyidae),a leaf spot fungus (Phleospora aceris [Lib.] Sacc.), and wind.

Other forest insects and diseases active in the FundyNational Park part of the model forest include the early birchleaf edgeminer (Messa nana Klug), birch casebearer (Coleo-phora serratella L.), spruce bud scale, (Physokermes piceaeSchr.), Sirococcus shoot blight (Sirococcus sp.), yellow witches’-broom of balsam fir (Melampsorella caryophyllacearumSchröter), needle casts, and snow blight. Browsing by mooseand deer was also common on young balsam fir.

An Inhabited Forest

This model forest is located in the Bas-Saint-LaurentRegion, Quebec, and covers 112 000 ha. The stands of whitespruce, balsam fir, white birch, yellow birch, and sugar maplewhich cover most of the area are typical of the Atlantic Mar-itime Ecozone.

A major objective of this model forest is to demonstrate thatthe concept of sustainable development can be integrated intocommunities based on agriculture and forestry. To achieve this,managers are developing models for forest farmers and for theconsolidation and diversification of the activities of owners ofsmall woodlots.

This forested area has been widely used and is an intimatemix of private and public lands. Fire has not played an impor-tant role in forest succession. Forests have been damaged byvarious insects, particularly the eastern spruce budworm, theforest tent caterpillar, and the hemlock looper.

Two ARNEWS plots are in the model forest and containwhite spruce, balsam fir, white birch, yellow birch, and sugarmaple. Tree condition was generally good for balsam fir andwhite spruce. No mortality occurred in 1993. Most of the treesare in crown condition class 3, 60% for balsam fir and 80% forwhite spruce with low levels of crown damage.

Similarly the hardwoods were in good condition. Whitebirch and sugar maple had >90% of their crowns in the healthiestclass. Sugar maples and red maples have trace levels of foliardamage caused by various insects and most of the trees havetrace or 10% damage caused by leaf spots or anthracnose. Only


one tree, a yellow birch, has more than 25% dead branches in thecrown from a large basal wound. All yellow birch had tracelevels of damage from a leaf edgeminer. However, yellow andwhite birches in the model forest are quite healthy comparedwith elsewhere in Quebec, probably due to their younger age.

Eastern Ontario Model Forest

The Eastern Ontario Model Forest covers 1.5 million ha ofthe Mixedwood Plains Ecozone. Most of the trees in this pre-dominantly hardwood area are less than 80 years old. Approx-imately 88% of the forested land is privately owned. The EasternOntario Model Forest’s unique uses of the forest resource includemaple syrup production and the use of black ash by the Mohawkpeoples to make traditional handicrafts. From ecologicalwoodland restoration initiatives to the establishment of nutgroves and the monitoring of forest songbird populations, theEastern Ontario Model Forest projects are as diverse as theecosystems that form the landscape. All share the common goalof using the forest resource in a sustainable manner.

This settled area has a long history of land use as farmwoodlots; management activities consist of selective cutting anddevelopment of fast-growing plantation species. A stress factoris defoliation of hardwoods by the forest tent caterpillar (Mala-cosoma disstria) and the gypsy moth (Lymantria dispar L.)

There are two ARNEWS plots in the model forest con-taining white spruce and sugar maple. One white spruce treedied in 1993 from natural competition. Tree crowns were in goodcondition—97% were in class 3. Moderate to severe defolia-tion by the eastern spruce budworm occurred on 50% of thewhite spruce. Sugar maples were also healthy; all trees were inthe healthiest three classes. Results from other forest healthmonitoring plots in the area showed similar results. For exam-ple, plots in the North American Maple Decline network andplots in another FIDS network showed nearly all trees to be inthe healthiest classes. Some defoliation was caused by themaple webworm (Tetralopha asperatella [Clem.]) but it didnot affect tree health.

A survey of red oak in the model forest showed that 61%of the trees had <20% dieback, 32% had 21–50% dieback,and others were more severely affected. The condition of oakhas improved in this area since 1992. Damage on these treeswas caused by a variety of defoliating insects, mainly gypsymoth, coupled with the effects of drought. No symptoms ofdamage by air pollution were observed, although this modelforest is in an area of relatively high pollution.

Lake Abitibi Model Forest

The Lake Abitibi Model Forest in northeastern Ontariocovers 1 094 690 ha in the Boreal Shield Ecozone near

Cochrane and Iroquois Falls. The model forest is characterizedby flat lowland peat sites that mainly support black spruce.

The model forest is testing new silvicultural methods andother projects. The goal is to protect unharvested trees moreeffectively, leaving them standing and able to form the nextforest. Research projects are also studying how small mam-mals are affected and how the fertility of these sites is affectedby harvesting.

A cultural heritage project was initiated to study the his-tory of the First Nations and nonnative use of the forest. Theproject has discovered and recorded several archaeologicalsites; the information will be used in the Timber ManagementPlanning process to protect these sites from disturbance.

Forests in this area are boreal and largely of fire origin.Forests have been harvested over extensive areas; damage byinsects has not played a large part in forest succession or foresthealth. Damage by the eastern spruce budworm and the jackpine budworm has been recorded frequently, however.

There are two ARNEWS plots in the model forest. Thespecies reported on are black spruce and white birch. All blackspruce are in the healthiest class and no damage was observedin 1993. About three quarters of the birch are in the healthiestclasses. No defoliation or pests were observed in the plots in1993.

Manitoba Model Forest

The Manitoba Model Forest covers 1 047 069 ha and islocated 100 km northeast of Winnipeg at the longitudinalcenter of Canada in the Boreal Shield Ecozone. Land owner-ship and use within the area is complex and diverse, includingmulti-use and wilderness parks, private woodlots, First Nationreserves, provincial forests, and a Forest Management Arealicensed to a newsprint company.

The diversity of ecosystems and land uses within themodel forest area requires an equally diverse program ofactivities. The projects include studying biophysical baselinedata, such as the songbird and plant census; the developmentof decision support models for moose and caribou; the devel-opment of a forest ecosystem classification system; forestregeneration techniques; harvesting systems; and economicdiversification studies.

Forest types are composed of typical Boreal ShieldEcozone forests, many of which are of fire origin. The majorinsects affecting forests are the jack pine budworm and theforest tent caterpillar.

The Manitoba Model Forest contains one plot of trem-bling aspen established in 1993. When the plot was estab-lished, two thirds of the trees were dead, caused by naturalthinning. The remaining trees were generally healthy and hadsome defoliation by a leaf beetle (Chrysomela sp.). Decay by


false tinder conk (Phellinus tremulae [Bond.] Bond. & Boriss.)and poplar peniophora (Peniophora polygonia [Pers.:Fr.] Bourd.& Galz.) was observed. The balsam fir were healthy and hadlight levels of damage caused by the eastern spruce budwormand the false balsam gall midge. Black spruce in the area wasalso in good condition and had little foliar damage.

Prince Albert Model Forest

The Prince Albert Model Forest covers 314 649 ha of theBoreal Shield Ecozone in central Saskatchewan. The moststriking features of this model forest are a strong commitmentto increase the participation of First Nations people in forestresource management, to advance the application of decision-making tools, and to promote the integration of research intoforest management decisions. The model forest ecosystem ischaracterized by large-scale disturbances, predominantlywildfire, and a dry cool climate. Several ecological researchprojects have been established to investigate the effects offorest management practices and wildfire on water, soilfertility, and biodiversity.

Forests have been affected by several insects and diseases,most particularly the jack pine budworm, the eastern sprucebudworm, and the forest tent caterpillar.

The Prince Albert Model Forest contains one ARNEWSplot established in 1993. Most of the trees are white spruceand trembling aspen. White spruce trees were generallyhealthy in 1993; 72.6% of the trees were in the healthiestclasses. A few of the white spruce are suppressed and theircondition is poor. The only pest found on white spruce waspale spruce gall adelgid (Adelges laricis Vallot).

The health of trembling aspen was good; 77.7% of thetrees were in the healthiest classes. Two pests contributed todecline in tree condition. The most prevalent was the defolia-tor large aspen tortrix, which caused moderate to severe defo-liation to most trees in the plot; poplar borer (Saperda calcarataSay) caused occasional damage.

Foothills Model Forest

The Foothills Model Forest covers about 1.2 million ha offorested land in the Boreal Plains Ecozone. It is a partnershipbetween Weldwood of Canada Ltd., the Alberta ForestTechnology School, and the Department of EnvironmentalProtection. Over 70 other organizations also participate.

These forests are affected by harvesting, wildfire, andoccasional abiotic damage from drying winds. The majorinsect pests affecting these forests are bark beetles, forest tentcaterpillar, and jack pine budworm.

The Foothills Model Forest contains one ARNEWS plotestablished in 1993. The plot is mostly white spruce and trem-

bling aspen, with some black spruce and lodgepole pine. Whitespruce are generally healthy; 91.3% were in the healthiestclasses. No pests were observed on white spruce or blackspruce. Trembling aspen were also healthy. The large aspentortrix caused some defoliation and contributed to some declinein tree condition. The few lodgepole pine in the plot wereaffected by the needle cast Lophodermella concolor (Dearn.)Darker, which contributed to the reduced vigor of the trees. Theneedle cast is common throughout the foothills of Alberta.

McGregor Model Forest

The McGregor Model Forest covers 181 000 ha in centralinterior British Columbia. It is part of the Montane CordilleraEcozone; major species include Engelmann spruce, subalpine fir,and some interior Douglas-fir. The forest is valued by local com-munities for forest products and services, recreation, scenic quali-ties, outdoor settings, ecological features, and cultural values.

The forest has been affected by harvesting, wildfire, andoccasional outbreaks of defoliating insects and bark beetles.There is one ARNEWS plot in the model forest established in1985. It contains Engelmann spruce and alpine fir as the majorspecies, plus a few interior Douglas-fir. Since plot establish-ment, two white spruce and two alpine fir have died fromstem breakage, likely during the high winds in the winter of1987–1988. In 1993, a single white spruce died, also weak-ened by storm damage. It was attacked by bark beetle (Dry-ocoetes affaber [Mannerheim]), a secondary organism damagingweakened trees. Otherwise, tree condition was good; therewas a light level of defoliation by the two-year-cycle budworm(Choristoneura biennis Free.), and some branch distortioncaused by the Cooley spruce gall adelgid (Adelges cooleyiGill.).

Other surveys by FIDS in the model forest include thoseof young stands, and the evaluation of a silvicultural trial.The white pine weevil (Pissodes strobi Peck.) was the mostcommon and significant pest on Engelmann spruce. Itoccurred in five of the six stands and killed 9% of the terminalshoots. In the silvicultural treatment trial, the spruce weevilattacked 65% of the terminal leaders. Other pests causingdamage included spruce gall adelgid, spruce bud moth,fir– fireweed rust (Pucciniastrum epilobi Otth.), and spruceneedle rust (Chrysomyxa ledicola [Peck] Lagerh.).

Long Beach Model Forest

The Long Beach Model Forest is situated on the westcoast of Vancouver Island, British Columbia, in the PacificMaritime Ecozone. Covering 400 000 ha, the area includesPacific Rim National Park and Clayoquot Sound. The forest isa patchwork of diverse and interrelated forest ecosystems,


much of it never having been harvested. Wildfires are notcommon in this wet ecozone.

Forest pests include defoliators of hemlock, cedar, and toa lesser extent the true firs. Defoliating insects are currently atendemic levels while only the more perennial pests such asdwarf mistletoe, root rots (Phellinus, Armillaria sp.), andspruce weevil are presently active at damaging levels. Moni-toring of these and other forest insects and diseases will con-tinue and will be enhanced with the establishment of anARNEWS plot within the model forest in 1995.

Conclusions

The assessment of ARNEWS plots in 1993 indicates thatthere is no large-scale decline in the health of Canadian foreststhat can be attributed directly to atmospheric pollution. Thisconclusion is similar to that reached from previous assess-ments. Damage caused by air pollution was described on birchin the Bay of Fundy area of New Brunswick. Localizeddeclines were reported for red oak and red pine. Flecking onpine needles was observed in the Atlantic Maritime Ecozone.The cause of these declines and the flecking damage is cur-rently being investigated. The effects of insects, diseases,drought, and storms were observed frequently. It is possible, ofcourse, that trees have been weakened or stressed by externalfactors such as air pollution but this stress is not apparent.

Tree mortality was 1.0% in 1993. Among conifers it was0.8% and among hardwoods 1.5%. Most mortality was causedby natural thinning. Higher than average levels of mortalityoccurred in jack pine, balsam fir, white birch, and tremblingaspen. The cause of this mortality was blowdown, root rots,stem cankers, and the eastern spruce budworm or other defo-liating insects. Air pollution was the cause of higher thannormal mortality in white birch.

In the boreal ecozones, extensive areas of forest continueto be affected by defoliation caused by jack pine budworm,eastern spruce budworm, forest tent caterpillar, and birchskeletonizer. The results indicate a continuing recovery fromthe effects of earlier droughts that had a negative impact ontree health in the southern parts of the Boreal Shield Ecozoneand the Mixedwood Plains Ecozone. In the northwestern partof the Boreal Shield Ecozone and in the Boreal PlainsEcozone, higher than normal mortality of trembling aspen wasattributed to a combination of insects, diseases, and unseasonalfrosts acting on old, unhealthy trees. In the Pacific MaritimeEcozone, most mortality was caused by storm damage.

Canadian forests appear to be generally healthy, althoughaffected by insects, diseases, and abiotic factors. The presenceof air pollution damage on white birch and possible damage topines and some other species are cause for concern. Research

projects will investigate the causes of this damage. It is essen-tial to continue the long-term monitoring of the health of ourforests to provide the knowledge base necessary for the sus-tainable development of our forests.

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