Old Growth Forest Definitions for Ontario · Old Growth Forest Definitions fortOntario / 1 Executive Summary T his Old Growth Forest Definitions for Ontario report provides working

Old

Growth

Forest

Definitions

for

Ontario

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Old Growth

Forest Definitions

for Ontario

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© 2003 Queen’s Printer for Ontario

Printed in Canada

Single copies of this publication are available from:

Natural Resources Information Centre300 Water StreetP.O. Box 7000Peterborough, ONK9J 8M5

Current publications of the Ontario Ministry ofNatural Resources and price lists are also availablefrom this office.

Telephone inquiries about ministry programs andservices should be directed to the Natural ResourcesInformation Centre in Peterborough:

General Inquiry: 1-800-667-1940Renseignements en français: 1-800-667-1840FAX: 1-705-755-1677E-mail: [email protected]

Other government publications are available fromPublications Ontario, Main Floor, 880 Bay St., Toronto,Ontario. For mail orders write Publications Ontario,50 Grosvenor St., Toronto, ON M7A 1N8

This publication should be cited as:

Uhlig, P., A. Harris, G. Craig, C. Bowling, B. Chambers,B. Naylor and G. Beemer. 2001. Old growth forestdefinitions for Ontario. Ont. Min. Nat. Res., Queen’sPrinter for Ontario, Toronto, ON. 53 p.

Le présent document, de nature technique et àdistribution limitée, n’est disponible qu’en anglais envertu du règlement 411/97, en application de la Loi surles services en français. Cependant nos lecteursfrancophones trouveront en page 2 un sommairerédigé en français où ils pourront s’informer des pointsprincipaux du document. Pour de plus amplesrenseignements en français, prière de s’adresser aubureau du MRN le plus proche.

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In Memoriam

During the final preparations of this reportour dear friend and colleague Brenda Chambers

succumbed to long-term illness.

Her skill and insight as an ecologist and hergreat spirit and courage will be sorely missed.

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T a b l e o f C o n t e n t s

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Résumé . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Authors and Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

An Ecological Context for Ontario Forests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

The Challenge of Defining Old Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Evolving Old Growth Forest Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

The Ecological Context for Ecosystem Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

The Ecological Regions of Ontario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

The Boreal Forest Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

The Great Lakes-St. Lawrence Forest Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1

The Deciduous Forest Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

The Ecological Land Classification Framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

The Analytical Approach to Defining Old Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

The Boreal (West and East) Forest Region (ecoregions 3E, 2W, 3W, 4W, 3S, 4S, 5S) . . . . . . . . . . . . . . . . . . . . 14

The Great Lakes-St. Lawrence Forest Region (ecoregions 4E and 5E) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

The Deciduous Forest Region (ecoregions 6E and 7E) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

The Boreal-West Forest Region (ecoregions 2W, 3W, 4W, 3S, 4S, 5S) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

The Boreal-East Forest Region (ecoregions 3E) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

The Great Lakes-St. Lawrence Forest Region (ecoregions 4E and 5E) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

The Deciduous Forest Region (ecoregions 6E and 7E) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Summary and Next Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Appendix B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Database Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Boreal Forest Databases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Great Lakes-St. Lawrence Forest Databases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Appendix C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Analysis Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Analysis Methodology for Boreal Forest Databases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Analysis Methodology for Great Lakes-St. Lawrence Forest Databases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Analysis Methodology for Deciduous Forest Databases (Site Regions 6E and 7E) . . . . . . . . . . . . . . . . . . . . . 42

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Old Growth Forest Definitions fortOntario / 1

E x e c u t i v e S u m m a r y

This Old Growth Forest Definitions for Ontarioreport provides working definitions foridentifying old growth in Ontario’s forests.

These definitions will be used with existing inventorydata and approaches to identify forest stands andlandscapes that have achieved old growth condition.

The methodology in the report complements effortsby the Ontario Ministry of Natural Resources (MNR) tocomply with Terms and Conditions 80, 81, 97 and103(a) of the 1994 decision of the OntarioEnvironmental Assessment Board on the ClassEnvironmental Assessment for Timber Managementon Crown Lands in Ontario (Timber EA).

The report enhances the definitions provided in thefinal report of the Old Growth Forests Policy AdvisoryCommittee, Conserving Ontario’s Old Growth ForestEcosystems (MNR 1994). These definitions alsosupplement the preliminary characterization of oldgrowth by Carleton and Arnup (1993).

The report identifies current old growth conditions.MNR developed the old growth definitions within theframework of the Ontario Ecological Land Classification(ELC). The report provides definitions for all forestedELC ecosites and all major tree species or forestcommunity associations present in the province. Thedefinitions also include all landscape conditionscaptured by the ELC framework. The frameworkpermits a closer examination of associated structuralfeatures of old growth, such as the occurrence andabundance of snags and downed coarse woodymaterials, successional trends, wildlife associations,and landscape dynamics. In addition, the frameworkprovides a context for understanding the diversity ofthe soils and sites, forest structures and plantcommunities associated with each of the tree speciesdescribed.

The report provides estimates of old growth age-of-onset and duration or persistency. It lists the estimatesby ELC ecosite areas within related ELC ecoregions.MNR analyzed an extensive compilation of plot dataspanning these ecological regions to derive thequantitative estimates for old growth age-of-onset.(The data is summarized in Appendix B.)

Results are presented in the form of four matrices.Each matrix represents one of the major forest regionsin the province – the Boreal (West and East), Great

Lakes-St. Lawrence and Deciduous forests. To makethe results as useful as possible, estimates of oldgrowth age-of-onset and duration are provided by ELCecosite or ecozone and forest tree species or forestcommunity associations, as well as by aggregated orgeneralized stand conditions, known as forest units.

The definitions should allow forest planners andmanagers to query currently available ecosystem andforest inventory databases to identify old growthconditions when they are developing spatially explicitstrategies for conserving old growth in forests.Planners can use the definitions to identify old growthconditions:

• that exist today, using available forest resourceinventory and/or remote sensing data;

• that existed in the past, using reliable historicalrecords; and

• that will exist in the future, using predictions offuture forest conditions.

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2 / Old Growth Forest Definitions fortOntario

R é s u m é

Ce rapport sur les définitions relatives aux forêtsanciennes vise à définir les termes propres auxforêts anciennes de l’Ontario. Ces définitions,

données sur l’inventaire actuel et méthodes serviront àidentifier les peuplements forestiers et paysages quiportent des forêts anciennes.

La méthodologie proposée pour produire lesdéfinitions contenues dans le rapport, comme lesautres efforts du ministère des Richesses naturelles(MRN) de l’Ontario, se conforme aux conditions nos80, 81, 97 et 103(a) de la décision de 1994 de laCommission des évaluations environnementalesconcernant l’évaluation environnementale de portéegénérale sur le bois d’œuvre des forêts de la Couronnede l’Ontario.

Ce rapport met en valeur les définitions fournies dansle rapport final du Comité consultatif de la politiquesur les forêts anciennes Préserver les écosystèmes deforêts anciennes de l’Ontario (MRN, 1994). Cesdéfinitions s’accordent avec les caractérisationspréliminaires de Carleton et Arnup sur les forêtsanciennes (1993).

Les définitions des forêts anciennes s’inscrivent dans lecadre du Programme de classification des terresécologiques (CTÉ). Le rapport reconnaît les conditionsactuelles caractérisant la forêt ancienne. Le cadre duCTÉ permet d’effectuer un examen plus approfondides caractéristiques structurelles associées aux forêtsanciennes, telles que : la présence et l’abondance dechicots et de débris de bois gisant au sol; les tendancesà la succession; les espèces fauniques en rapport avecl’écosystème; et la dynamique du paysage. En outre, lecadre fournit un contexte utile à la compréhension dusol et du terrain et de la diversité structurelle etvégétale associée à chaque essence. Les définitionscomprennent tous les types de paysages classés dans lecadre de la classification des terres. Toutes lesconditions de paysage comprises dans le cadre du CTÉse retrouvent dans les définitions.

On y trouve une estimation de l’âge marquant lecommencement d’une forêt ancienne et sa durée ou sapersistance, selon dans les cinq principales zonesécologiques des écorégions en question. Unecompilation approfondie des coordonnées a permisd’arriver à une estimation quantitative ducommencement d’une forêt ancienne (Annexe B).

Les résultats se présentent en quatre matrices, chacunereprésentant une des principales régions forestières dela province : boréale ouest, boréale est, GrandsLacs/Saint-Laurent et feuillus. Pour une utilitémaximale, les estimations de l’âge du commencementet de la durée d’une forêt ancienne sont offertes parécosite ou écozone de la CTÉ et par essence d’arbre ouespèces associées à la forêt et selon la condition dupeuplement (agrégé ou généralisé), soit des « unités »de la forêt.

Ces définitions devraient permettre aux planificateurset gestionnaires des forêts, d’examiner les bases dedonnées actuelles sur les écosystèmes et l’inventaireforestier, afin de reconnaître des conditions propres àla forêt ancienne, quand ils visent à élaborer unestratégie localisée pour conserver la forêt ancienne :

• aujourd’hui, avec l’inventaire actuel des ressourcesforestières et les données de télédétection;

• jadis, avec les dossiers historiques fiables; et

• à l’avenir, avec des prévisions pour les futures forêtsanciennes.

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Authors and Acknow ledgement s

AuthorsThe following people were responsible for theproduction of this report and the analysis of datasets:

Peter Uhlig – Forest Ecologist, Provincial TerrestrialAssessment Program, MNR, Sault Ste. Marie

Anne Harris – Senior Policy Advisor, Forest ManagementBranch, MNR, Sault Ste. Marie

Grant Craig – Forest Program Specialist, Forest ManagementBranch, MNR, Thunder Bay

Colin Bowling – Stand Management Forester, NorthwestScience and Technology, MNR, Kenora

Brenda Chambers – Deceased.

Brian Naylor – Habitat Biologist, Southcentral ScienceSection, MNR, North Bay

Garnet Beemer – Resource Planning Analyst, MNR,Nipigon

AcknowledgementsMany colleagues made significant contributions. Wethank them for sharing data, analytical assistance andecological expertise. Contributors include:

Boreal-WestScott Hole – Judicial Review Forester, MNR, Nipigon

Mark Roddick – Growth and Yield Specialist, TerrestrialAssessment Unit, MNR, Thunder Bay

Chris Sawula – Data Analyst, Terrestrial AssessmentUnit, MNR, Thunder Bay

Bill Towill – Senior Silvicultural Specialist, NorthwestScience and Technology, MNR, Thunder Bay

Robert Whaley – Data Analyst, Northwest Science andTechnology, MNR, Thunder Bay

Boreal-EastRob Arnup – Consulting Ecologist, Timmins

Simon Bridge – Landscape Ecologist, Northeast Scienceand Technology, MNR, South Porcupine

Alison Luke – Stand Dynamics and Silviculture Specialist,Northeast Science and Technology, MNR, SouthPorcupine

John Parton – Growth and Yield Specialist, Terrestrial

Assessment Unit, MNR, South Porcupine

Kim Taylor – Ecologist, Northeast Science and Technology,

MNR, South Porcupine

Stan Vasiliauskas – Ecologist, Northeast Science and

Technology, MNR, South Porcupine

Bob Watt – Terrestrial Ecosystems Team Leader, Northeast

Science and Technology, MNR, South Porcupine

Gary White – GIS Specialist, Northeast Science and

Technology, MNR, South Porcupine

Central OntarioBrian Batchelor – Co-ordinator, Southcentral Science

Section, MNR, North Bay

Tim Bellhouse – Wildlife Assessment Unit Leader,

MNR, North Bay

Dave Heaman – Fire Science Specialist, Eastern Fire

Region, MNR, Peterborough

Gillian Holloway – Project Biologist, Southcentral

Science Section, MNR, North Bay

Daniel Kaminski – Systems Specialist, Southcentral


Dave Nesbitt – Database Analyst, Southcentral Science

Section, MNR, North Bay

Fred Pinto – Conifer Program Leader, Southcentral


Murray Woods – Growth and Yield Specialist, Terrestrial

Assessment Unit, MNR, North Bay

Southern OntarioGreg Greer – Growth and Yield Specialist, Terrestrial

Assessment Unit, MNR, London

Harold Lee – Ecologist, Southcentral Science Section,

MNR, London

Tim Williams – Growth and Yield Specialist, Terrestrial

Assessment Unit, MNR, London

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Au thors and Acknow ledgement s

Ontario Forest Research InstituteSylvia Greifenhagen – Forest Pathologist, OntarioForest Research Institute, MNR, Sault Ste. Marie

John Johnson – Ecologist and GIS Specialist, ProvincialTerrestrial Assessment Program, MNR, Sault Ste. Marie

Sean McMurray – Ecologist and GIS Specialist, ProvincialTerrestrial Assessment Program, MNR, Sault Ste. Marie

Frank Schnekenburger – Forest Landscape Analyst,MNR, Sault Ste. Marie

Jan Vassbotn – GIS Specialist, Provincial TerrestrialAssessment Program, MNR, Sault Ste. Marie

This project was made possible in part by theCanadian Foundation for Innovation (CFI), theOntario Innovation Trust (OIT), the Sault College ofApplied Arts & Technology, and the Upper LakesEnvironmental Research Network (ULERN). Theircollaboration has advanced innovation in the scienceof natural resources and their management.

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I n t r o d u c t i o n

In the late 1980s and early 1990s, conflicts aroseover the old growth in Ontario’s Crown forests. Theconflicts mainly focused on timber harvesting

operations in wilderness areas and the old growth redand white pine forests in the Temagami area. However,the old growth issue emerged as a complexcontroversy that involved a range of ecological, socialand economic values across the province. At the time, there were no objective criteria foridentifying old growth or consistent definitions of oldgrowth. The parties to the conflict therefore found itdifficult to communicate about the issue or achieveconsensus on conservation objectives.

Many of the ecological, social and economic valuesrelated to old growth underlay some of the issuesraised at the hearings held on the Ontario Ministry ofNatural Resources (MNR) Class EnvironmentalAssessment for Timber Management on Crown Landsin Ontario (Timber EA) from 1989 to 1994.

In January 1992, the Minister of Natural Resourcesappointed an Old Growth Forests Policy AdvisoryCommittee. The committee was an independent bodymade up of concerned citizens from across theprovince who volunteered their time to representvarious perspectives on old growth. The minister gavethe committee the mandate to makerecommendations on a strategy to address theconservation of old growth ecosystems in Ontario.MNR also established an independent ScientificAdvisory Committee to support the policy advisorycommittee with its investigation of old growth.

After considerable public input and consultation, thepolicy advisory committee submitted a final report,Conserving Ontario’s Old Growth Forest Ecosystems (MNR1994). The Minister of Natural Resources released thereport to the public on September 30, 1994.

The committee’s final report addresses a number of keyconcepts related to the conservation of old growth inforest ecosystems. It includes tables that define oldgrowth in Hills site regions for major tree speciespresent in Ontario. Hills site regions, developed byscientist Angus Hills, divide Ontario into ecologicalregions based on a combination of climate, physicalgeography and biological productivity. The final reportalso contains recommendations covering seven broadareas:

• landscape management;

• protected areas;

• forest management;

• integrated decision-making (evaluation framework);

• research;

• education and information; and

• implementation and monitoring.

The final report of the policy advisory committee

stopped short of providing direction on how to

identify forest stands and landscapes with old growth

characteristics within an ecological information

framework.

Meanwhile, in April 1994, the Environmental

Assessment Board released the Terms and Conditions of

Approval for the Class Environmental Assessment for

Timber Management on Crown Lands in Ontario. In this

decision, the board approved the MNR Timber

Environmental Assessment subject to 115 legally

binding terms and conditions. Term and Condition

103(a) states that, “During the term of this approval

(i.e., by May 2003), MNR shall investigate the subject

of old growth ecosystems and develop a policy to

provide an environmentally sound conservation

strategy and definitions of old growth specific to

Ontario forest conditions.”

The purpose of this report is to provide definitions of

old growth specific to Ontario’s forest conditions and

respond to the recommendations made by the Old

Growth Forests Policy Advisory Committee to:

1. place definitions of old growth forest into the

context of Ontario’s Ecological Land Classification

(ELC) framework for identification, classification

and inventory. This includes the use of ecosystem

classification terminology (i.e., ELC ecoregions,

ecodistricts and ecosites), and allows for the

development of old growth definitions for all major

forested ecosystems and tree species present in

Ontario

2. provide an approach to old growth definition

focused on quantitative evaluation and comprehensive

analysis of all available plot networks and datasets.

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In addition to these primary objectives, the report

provides:

• a compilation and review of pertinent literature

reflecting the current understanding of old growth

forest ecosystems, their ecological context, and

approaches to definitions;

• a compilation and description of existing

quantitative databases that assist in the

characterization of old growth forest systems;

• a comparison of old growth forest ecology across

Ontario and with adjacent jurisdictions; and

• estimates of old growth age-of-onset for forested

ecosites and operational forest units in the Boreal

and Great Lakes-St. Lawrence ecoregions.

This report sets neither policy nor regulatory direction

for old growth conservation. Instead, it provides those

involved in policy development, land use planning,

natural heritage planning, and forest management

planning with an objective and comprehensive set of

old growth definitions. The ELC framework and

specific linkages to forest inventory and planning

units should facilitate the identification of old growth

in Ontario’s ELC ecoregions or forest landscapes. Once

planners can identify and quantify old growth

characteristics reliably, it will be possible to provide

spatially explicit estimates of old growth occurrence,

abundance and distribution. This information can

then be used as a basis for developing conservation

objectives at a variety of ELC spatial scales.

The criteria and standards contained in this report for

the identification of old growth in forest stands,

ecosystems and landscapes represent one of a number

of steps required to complete a comprehensive set of

classification, inventory, policy and decision-support

tools. These tools will be used to conserve old growth

in defined forest units in Ontario, and associated

ecological, social, cultural and economic values. The

report enhances the initial definitions provided in the

final report of the policy advisory committee. The

definitions in this document also supplement the

characterization by Carleton and Arnup (1993). The

authors used an extensive compilation of plot data to

develop quantitative estimates for the old growth age-

of-onset.

Next steps in the study and characterization of old

growth in Ontario’s forests will involve the use of

these definitions and identification criteria and

standards in an expanded landscape analysis of old

growth conditions for the major tree species or forest

community associations present in Ontario. This will

include analysis based on geographic information

systems (GIS) for large areas of the province. It will

also include investigation into associated

characteristics of old growth, including species

diversity, structural diversity (such as the presence and

abundance of downed woody materials and snags)

and trends in old growth abundance or rarity. In

addition, the expanded landscape analysis will look

at processes of human and natural disturbance, and

landscape distribution.

Future work will supplement these old growth

definitions and analyses with stand and landscape

studies of the ecological forces influencing the

occurrence and change in forest structure over time.

This work will embrace the concept of ecosystem

conditions at various landscape scales that are

dynamic and constantly changing. Understanding

these changes over time will allow scientists to

enhance support tools designed to predict forest

ecosystem conditions in the future. The information

and knowledge gained from these support tools will

form the basis for long-term monitoring, assessment

and reporting on progress made to conserve old

growth and its unique values in Ontario’s forests. The

results presented in this report complement work

underway in support of Timber EA Terms and

Conditions 80, 81 and 97.

This report includes a description of old growth within

the context of the ELC framework. Results are presented

in the form of four matrices defining old growth for

Ontario within the context of the province’s ecological

regions (i.e., the Boreal (west and east), Great Lakes-St.

Lawrence, and Deciduous Forest regions). The report

provides estimates of old growth age-of-onset and

duration for a wide variety of forest ecosystems. It

includes comparisons to definitions, characteristics and

dynamics of old growth found elsewhere. A summary

examines current data as well as recommendations for

further study.

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In addition, this report includes results of analysisusing regional operational forest units for the Boreal(west and east) Forest region. Appendix A presentsresults for these management and inventory orientedforest classes to facilitate the incorporation of oldgrowth definitions into current forest managementplanning on Crown lands.

Summaries of the plot databases and the analyticalmethods employed in the development of these oldgrowth definitions are provided in Appendices Band C, respectively.

This old growth definitions report has been preparedto complement and support the Old Growth Policy forOntario's Crown Forests – Version 1 (MNR 2003).Policy developers, resource management planningteams, resource managers, specialists andpractitioners should consult the old growth policy toensure the appropriate use of this report.

The Old Growth Policy for Ontario's Crown Forests andthe report Old Growth Forest Definitions for Ontariohave been prepared to comply with Term andCondition 103 (a) of the Reasons for Decision andDecision: Class Environmental Assessment by theMinistry of Natural Resources for Timber Managementon Crown Lands in Ontario (EnvironmentalAssessment Board 1994).

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The Challenge of Defining OldGrowth

In the 1980s and 1990s, the public and scientificcommunity across North America expressedconcerns about the effect of timber harvesting on a

wide variety of ecosystems. A century or more ofcumulative impacts associated with large areas ofharvesting, extensive establishment of plantations,intensive management practices and use of exoticspecies had resulted in major shifts in the compositionand age structure of the forest ecosystem. Locally,individuals and groups expressed concerns about theloss of the features and related ecological functions ofold growth in Ontario’s forests.

First in the Pacific Northwest of the United States, andthen almost simultaneously across North America andaround the world, attention focused on the harvestingof what became known as “old growth forest” or “oldgrowth ecosystems”. Early debate took place primarilyin the popular press and through public protest.Governments, natural resource agencies and industrystruggled to respond to public criticisms and developthe scientific understanding needed to providecredible approaches to regulation and conservation.

Scientific studies in the US Pacific Northwest began toidentify the myriad of functional relationships thatforests and landscapes depend on (Grier and Logan1977; Franklin et al. 1981, 1986; Franklin and Spies1984; Harmon et al. 1986; Thomas et al. 1988).Increasingly, studies showed forests to be criticalproviders of essential environmental services such asair and water purification, maintenance of globalbiogeochemical cycles and carbon sequestration(Maser and Sedell 1994). As these investigationscontinued, initial definitions and characterizations ofold growth emerged and were applied to the inventoryand evaluation of various regional forest conditions.Ultimately, these definitions have been used todevelop alternative management practices designed tobetter conserve old growth conditions in forests aspart of a continuum of forest conditions acrossforested landscapes (Thomas 1979; Harris 1984;Hammond 1992; Mladenoff et al. 1993).

The literature on old growth is extensive (seesummaries by Davis 1996a and b, Tyrell et al. 1998,Natural Areas Assoc. 1998, World Wildlife Foundation

France 2000). There is also considerable diversity inthe approaches used to define old growth and to assessits significance in forest stands and ecosystems andacross forested landscapes. Numerous authors fromacross North America (e.g., Alaback 1984, Franklin andSpies 1984, Hunter 1989, Hayward 1991, Kimmins1992, Keddy 1994b, Staab 1996, Batista and Platt1997) have considered many criteria as indicators ofold growth conditions. These may include any or all ofthe following:

• large old trees for species and site;

• complex stand structure characterized by widevariation in tree size and spacing, with multiplecanopy layers and canopy gaps;

• large dead standing trees and accumulations ofdowned woody materials, tip-ups and mounds;

• specific composition of the forest communitydescribed through the occurrence or changingabundance of certain associated species (e.g.,herbaceous plants, lichens and other bryophytes orwildlife species);

• few or no signs of human disturbance;

• net growth equal to or less than zero;

• age of dominant species exceeding average naturaldisturbance interval for ecosystem; and

• forest system near or in late succession or “climax”stage.

Several factors have contributed to this diversity indefinitions. Initial criteria developed in the US PacificNorthwest were based on the characteristics of coastal,cool-temperate rainforests and the perspective thatthese forests progress through an autogenic successiontowards a steady-state climax. As the issue of oldgrowth conservation spread across the NorthAmerican continent, many authors tried to apply thisinitial definition, at least during the early stages ofstudy and debate. Most of these attempts were seen tobe inappropriate, and efforts soon focused ondefinitions better suited to local ecology (e.g., Barnes1989).

This report does not provide a definition of “oldgrowth.” Instead, it provides a range of criteria (age-of-onset and duration) and a definition appropriate tothe forest ecosystems in Ontario within the consistent

An Eco log ica l Contex t forOntario Fores t s

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and hierarchical framework of the Ontario ELC. Thisapproach allows the patterns of old growthoccurrence, distribution and abundance to beunderstood within the context of regional patterns ofclimate, geology, soils, natural disturbance, andlandscape composition in Ontario. A hierarchical,ecological approach will lead to more meaningful andconstructive study and debate about the conservationof old growth in Ontario’s forests over the long term.The authors hope this perspective will facilitate thecomparison of the state of Ontario’s old growthconditions with those of other jurisdictions in thecontext of broader trans-boundary and continentalecological classifications.

Adding to the already complex nature of old growth isthe fact that the debate over old growth definitionshas been inextricably linked with a complex range ofsocial perceptions about wilderness preservation,aesthetics and spirituality, as well as economic orindustrial values. The old growth debate has oftenincluded terms a specific interest group considersimportant, such as ancient, overmature, pristine,decadent, virgin, senescent or wilderness. Old growthhas also been used as the focal point for discussions ofrarity, biodiversity, forest fragmentation and broadersocietal concerns about the sustainability of forestmanagement practices (Harris 1984; Maser 1988, 1994;Hunter 1990; Hammond 1992; Aplet et al. 1993;Maser and Sedell 1994; Voller and Harrison 1998).

The perception of time is also an important factor indefining old growth conditions. Early definitionstended to be time-static. They characterized extant oldgrowth conditions at the stand or species level in thecurrent forest inventory of an area. Old growth wasperceived as a permanent and unchanging feature ofthe landscape associated with a particular latesuccessional forest stage that was self-perpetuating.

More recently it has become clear that, depending onthe forest ecosystem type, old growth is notnecessarily a permanent feature in any one location. Itis dynamic, developing over time in a forest landscape,persisting for a variable length of time andredeveloping in different areas as natural disturbancessuch as fire reinitiate stand development.

A comprehensive landscape perspective for theassessment of old growth occurrence and dynamics isessential. This is not to say that there is no merit in

standard species-level characterization of old growth.Such characterization is particularly useful inlandscapes where old growth is exceptionally rare andremnants are often isolated examples of the originalcomposition of the forest landscape. It is, however,only part of a more comprehensive view.

Evolving Old Growth ForestDefinitionsLike other jurisdictions, Ontario has considered avariety of approaches for defining old growth.Building on the ecological understanding at the time,the final report of the Old Growth Forests PolicyAdvisory Committee, Conserving Ontario’s Old GrowthForest Ecosystems (MNR 1994) presented a generaldefinition as follows:

Old growth ecosystems are characterized by thepresence of old trees and their associated plants,animals and ecological processes. They show little orno evidence of human disturbance. (MNR 1994,Executive Summary, page 4)

While it was recognized that existing definitions fromother jurisdictions were not entirely applicable toOntario, there was a lack of specific data that could beused to refine Ontario’s old growth definitions. As aresult, the committee adopted a general and inclusiveapproach, with specific direction to MNR regardingthe need to collate the missing information andprovide a more detailed set of definitions.

The fact that all forest ecosystems vary in theirfunction and lifespan makes it difficult to applygeneral criteria to all old growth forest conditions.Carleton and Arnup (1993), in their comprehensivesurvey of white and red pine stands across Ontario,concluded that the main structural criterion for oldgrowth conditions in forests dominated by red andwhite pine was the presence of large old trees. Uniquefloristic and structural features were more difficult tospecify. Carleton and Arnup encouraged a dynamicapproach to the study of the uniqueness of the oldgrowth condition for all forest types over time.

To date, the dependence on a temporally static,species-level approach in Ontario has resulted in ageneral inability to capture either the composition andstructure of old growth or the occurrence and

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distribution of old growth at the community or foreststand level and at landscape levels. Furthermore, aspecies-oriented approach provides very limitedunderstanding of the temporal dynamics and thesuccessional patterns leading to and maintaining oldgrowth forest conditions across the landscape.

The ecosystem approach adopted in this reportprovides a more explicit description of the physicalsite, soil, stand structure and floristic compositionassociated with old growth. It also starts to take intoaccount the variability in dynamics (structure,disturbance) and species longevity that exists in forestecosystems. The results are presented in matrices thatplace old growth in a temporal context based on theage structure of an ecosystem (Hayward 1991).

In addition, the principles expressed by Barnes (1989)have been applied. They further expand upon theconcept of a dynamic system, with a variable naturedependent on landscape or site conditions andcharacterized within an ecoregional framework. Otherauthors in the Great Lakes region and eastern NorthAmerica have also worked within this context(Leopold et al. 1988; Duchesne 1994; Vora 1994; Tyrellet al. 1998).

The Ecological Context forEcosystem ClassificationDuchesne (1994) and Barnes (1989) suggest that acomprehensive approach to old growth definitionrequires an ecological framework. Old growth inforest ecosystems can then be placed in the properELC ecosite, spatial and successional context. Thisframework of ecologically defined units can then beused as a basis for the development of strategies forthe conservation of old growth as advocated byHunter (1990).

The process of ecosystem classification involves thedefinition of environmental domains at a variety ofspatial and functional scales (Bailey 1996). In ahierarchically organized system, broader scalesconstrain and define finer scales. Abiotic factors suchas climate, bedrock, surficial geology and topography,functioning at broad regional scales, define finer-scalebiological relationships such as species andcommunity occurrence, relative rates of productivity,

and patterns of disturbance and succession. Thesefactors result in unique patterns of forest ecosystemsin a dynamic mosaic that includes old growthconditions as a variable and dynamic component.

The Ecological Regions ofOntarioAn examination of the broad-scale patterns of forestoccurrence and development provides a starting pointfor better understanding old growth conditions in therange of forest types present in Ontario. The provinceis divided into three distinct forested regions (Rowe1972, Crins et al. 2001): the Boreal, the Great Lakes-St.Lawrence and the Deciduous Forest regions (Figure 1).Each region supports different tree species and forestecosystems. The landscapes have evolved in responseto differing patterns of disturbance. The age classstructure for any particular forest stand, forestecosystem or landscape mosaic depends on thelongevity of the component tree species present, thefrequency and intensity of disturbance, and the abilityof the component tree species to survive naturaldisturbances and human intervention.

The Boreal Forest RegionThe Boreal Forest region is part of a vast coniferousforest stretching across Canada. It is Ontario’s largestand most northern forested region. The region can bedescribed as generally having long, cold winters andshort, relatively cool summers. The topography is, forthe most part, made up of bedrock-dominated terrain,low in relief, with only local areas exceeding 200metres. Numerous lakes and wetlands occur across theundulating-to-rolling landscape. Most soils are derivedfrom relatively shallow, nutrient-poor glacial tills andglaciofluvial deposits, with somewhat richer clayplains in local areas. Extensive peatlands with organicsoils occur in many low-lying areas. The forest hasrelatively few tree species. In upland areas, jack pine,black spruce, white spruce, balsam fir, trembling aspenand white birch combine to form a complex mosaic.In low-lying areas with poor drainage, the forest ismade up of extensive stands of black spruce withadmixtures of tamarack. These tree species are alltolerant of the harsh growing conditions found acrossthe region.

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Several disturbances play an important role indetermining the structure and composition of Borealforest ecosystems and landscapes. Fire is an importantforce; it occurs more frequently in the Boreal forestthan anywhere else in the province. Reportedestimates of pre-settlement fire cycles vary across theBoreal Forest region, but generally fall in a range of 40to more than 200 years (Heinselman 1981, Bergeron etal. 2000 a and b). The frequency and intensity ofBoreal forest fires has generated a complex mosaic ofeven- and uneven-aged, pure and mixed species foreststands (Carleton and Maycock 1978; Carleton 1982).

Large areas of the Boreal Forest region are also affectedregularly by insect outbreaks such as spruce and jackpine budworm and forest tent caterpillar. These insectscan cause extensive mortality over vast stretches offorest and can significantly alter stand compositionand structure. There is also a complex interactionbetween insect-driven mortality and fire. Thecombined effect of these disturbances is a continualflux of age classes and species compositions across thelandscape. The exact impacts of active fire suppressionprograms are debatable. Additional influences due toclimate change may also affect the structure and agingprocesses in boreal forests. Finally, depending on theamount of forest harvesting and fire suppressionwithin a given forest management unit, there maynow be substantially different proportions of olderstands than would be present in a natural forest fireregime. Conclusive evidence for the impacts ofchanging fire regimes is still being developed andneeds to be carefully analyzed (Frelich and Reich1995).

For the purposes of this analysis, the Boreal Forestregion has been divided into western and easternportions. While the range of species and general soilconditions do not change dramatically within theBoreal Forest region, there are substantial differencesin the landscape patterns and successional trendsbetween the Boreal-West and Boreal-East Forestregions. The division is based on observations ofdistinctly different climatic patterns that result in aless humid and somewhat warmer climate in the west(Hills 1959, MacKey et al. 1996). The frequency,intensity and size of forest fires are also higher in thewest (Carleton and Maycock 1978, Cogbill 1984,Heinselman 1981, Lynham 1985, Donnelly andHarrington 1978, Baker 1989, Bergeron et al 2000).

These differences are important when one isattempting to understand the development andpersistence of old growth conditions in the BorealForest region.

The Great Lakes-St. LawrenceForest RegionOntario’s second largest forest region represents abroad transition between the Boreal Forest systems tothe north and the Deciduous forests to the south. Inthe Great Lakes-St. Lawrence Forest region thesummers are longer and warmer, and the winters,while long, are not as harsh as those in the BorealForest region. The topography of the region is highlyvariable. Some areas such as Algonquin Park, theAlgoma Highlands, the La Cloche range and theMadawaska Highlands feature rugged hilly terrain aswell as more subdued undulating plains. As in theBoreal Forest region, soils continue to be relativelynutrient-poor and exist mostly as a shallow veneer overthe bedrock-dominated terrain. Deeper sandy glacio-

Figure 1Rowe’s forest regions within Ontario(adapted from Rowe 1972)

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fluvial deposits are mostly confined to river valleys,and there are occasional clay plains in lower-lyingareas. Peatlands and other wetlands tend to be lessextensive and are confined by the more broken terrain.

The Great Lakes-St. Lawrence Forest region has adiverse combination of approximately 60 forest treespecies. Dominant conifer species include red pine,white pine, eastern white cedar, hemlock, balsam firand white spruce. Boreal species include black spruceand jack pine. Deciduous species include sugar maple,yellow birch, red oak, white and black ash, whitebirch, beech, basswood, black cherry, largetooth aspenand trembling aspen. Mixedwood stands composed ofseveral dominant species are common.

Fire has played an important but complex role in theGreat Lakes-St. Lawrence Forest region. Catastrophic,stand-replacing fires are less common than in theBoreal Forest region and are also believed to haveoccurred less frequently in the past. Fire returnintervals for intense stand-replacing burns areestimated to be more than 300 years. Periodicunderstory fires of variable intensity were morecommon (i.e., up to every 25 years). For mixedwoodsin which Boreal species dominate, the pre-suppressiondisturbance cycle has been estimated to be about 80years (Heinselman 1981). As in the Boreal Forestregion, effective fire suppression since the early 1900shas likely lengthened the natural fire cyclesignificantly (Day and Carter 1991). Fire use byaboriginal peoples could have been a very significantfactor in this region, although its extent and impactare not well understood.

Fire in the Great Lakes-St. Lawrence Forest region hashelped perpetuate forest ecosystems made up of fire-evolved major tree species such as red, white and jackpine; black spruce; oak species; and aspen pine.Current evidence suggests that the lower frequency ofcatastrophic fires and the lower intensity of the firesthat did occur were due to the mixed and hardwood-dominated composition of the forest. Frequentunderstory fires of low and moderate intensity arethought to have played an important role inestablishing and maintaining the pine and oak-dominated forests in the region.

Catastrophic wind and ice storms play an importantrole in the tolerant hardwood and hemlock forests ofthe Great Lakes-St. Lawrence Forest region (Canham

and Loucks 1984; Frelich and Graumlich 1994). Firehas also played a role in these forest types, with acombined wind/fire cycle estimated at 1000 years inlower Michigan (Whitney 1986) and upper Michigan(Frelich and Lorimer 1991). More common windevents, at the scale of a single tree or group of trees,result in constant in-growth and an uneven agestructure. Insects are another disturbance in theregion. Spruce budworm and forest tent caterpillar candefoliate large areas and can be very influential inchanging stand composition and structure. In general,forest stands in the Great Lakes-St. Lawrence Forestregion show a wide variation in age structure acrossthe landscape depending on the nature of thedisturbance regime. A lengthy period of humanoccupation and use has also led to significant changesin composition (White and Mladenoff 1994).

The Deciduous Forest RegionEuropean settlement and the clearing of forested landfor agriculture and urban development have reducedthe forests of the Deciduous Forest region to smallremnants (Keddy 1994a; Larson et al. 1999). Whilethis region is Ontario’s most diverse and productiveforest landscape, it is also the smallest and mostpressured by human activities. It represents thenorthern limit of a forest region, located mostly in theUnited States, that stretches southwards from lakesOntario and Erie through the Ohio and Mississippivalleys to Tennessee and the Carolinas and along theAtlantic coast. The climate is substantially warmer inthe Deciduous Forest region than in Ontario’snorthern forests, with short, mild winters and long,warm, humid summers. The bedrock geology changesdramatically south of the granitic PrecambrianCanadian Shield. Ordovician sandstones andlimestones predominate. Soils are variable, but aretypically deeper and more nutrient-rich than the soilsof the northern forests. With the exception of thesteep relief of the Niagara Escarpment, the topographyis undulating to rolling due to the flat bedrockunderlying the region.

Prior to European settlement and the extensiveclearing of the forest, mixed oak and chestnut forestsdominated dry upland areas. White pine and hickoryalso grew in these stands. On fresh to moist ecosites,mixed hardwood forests containing sugar maple, black

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cherry, hickory, red maple, elm, basswood, red oakand hemlock were found. On moist mineral ecositesand wet organic ecosites, bottomland forests of tuliptree, red maple, silver maple, elm, swamp white oak,black and green ash, and white and yellow birch werecommon. Unique environments along the ruggedNiagara Escarpment have also supported very old andslow-growing white cedar woodlands on the cliff faces.Along with the typical dominant species (e.g. sugarmaple, beech), this region contains numerous treespecies that have reached their northern limits. Theseinclude black gum, Kentucky coffee tree, cucumbertree, tulip tree, pin oak, and sycamore.

As in the Great Lakes-St. Lawrence Forest region,windthrow is thought to have been a major forceshaping the forests in this region. It occurred eitherthrough infrequent extensive storm events or throughmore common individual tree mortality or small patchevents (Heinselman 1981, Keddy 1994a). Fire wasmuch less common, but did occur occasionally. Itresulted in white pine, red pine and other coniferspecies more typical of the northern forest beingfound historically in the Deciduous Forest region(Keddy 1994a). Individual tree death due to insectdamage, age and disease is thought to be the mainagent of disturbance. This usually leads to a forest withnumerous small gaps that fill quickly through naturalregeneration.

The recent publication Woodland Heritage of SouthernOntario (Larson et al. 1999) provides an overview ofthe forest of southern Ontario and currentconservation dilemmas.

The Ecological LandClassification FrameworkA system of ecological regions and districts for Ontariowas developed by Hills (1961) and subsequentlymodified by Burger (1993) and Crins et al (in prep). Atbroad provincial scales it provides a more refined set ofecological planning units than the system developedby Rowe (1972).

Over the past 15 years, considerable effort has beenmade to develop a comprehensive ELC frameworknested within the ecological regions of Ontario(Figure 2) (Sims et al. 1997, Sims and Uhlig 1992,

McCarthy et al. 1994, Racey et al. 1996, Chambers et

al. 1997, Lee et al. 1998, Taylor et al. 2000). Using the

ELC framework, the finer-scaled regional

classifications explicitly describe relatively

homogeneous ecosystem units at the ecosite or forest

stand level (Figure 3). The classifications describe

ecosystems in terms of the composition and structure

of the vegetation, the specific soil attributes related to

moisture and fertility gradients, and the physical site

characteristics. Based on these variables, it is possible

to understand the major environmental forces shaping

the development of a given condition of the forest

ecosystem at the ecodistrict scale.

The Ontario ELC framework is the basis for forest

management planning and represents a common

language for multi-scale description, interpretation

and reporting on forest conditions. The classifications

are used for silvicultural interpretations and for

describing wildlife habitat conditions. Furthermore,

they provide an effective framework for organizing

hypotheses and stratifying research on wildlife habitat

and studies on forest composition and structure,

landscape ecology, growth and yield, and succession.

As a result, the Ontario ELC framework provides the

basis for organizing quantitative information on old

growth forests for this report.

Figure 2 Revised ecological regions for Ontario (from Crins and Uhlig in prep)

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The Analytical Approach toDefining Old Growth The development of old growth forest definitionsinvolved the collation and interpretation of regionallyspecific literature and the analysis of several extensiveregional datasets. These data are primarily derived fromplots established by the MNR ELC and Growth andYield programs, and a variety of regional growth andyield datasets from the forest industry (see Appendix B).They include point-in-time or repeated measurementsof tree species age, height and diameter in sample plots.Site and/or understory vegetation data were used toclassify plots to vegetation and soil-type conditions,and hence to ecosite, using current classification keys inthe existing regional ELC manuals.

It is important to note that the forest ecosystem classescapture not only pure stand/species conditions, butalso the full range of mixed species combinations.Where appropriate, old growth age-of-onset isreported for all of the major species that can dominateor typify a given site condition. Due to the uniquecharacteristics and geographic extent of the availabledata, different analytical paths were required for eachregion. However, common features were maintainedso that the results are comparable province-wide. Adetailed description of the data preparation and the

analytical steps followed in developing the old growthdefinition tables is provided in Appendix C.

The revised ecological regions for Ontario illustrated inFigure 2 (Crins, W. J. 2000. Ecozones, ecoregions,and ecodistricts of Ontario. MNR, Ontario Parks,Peterborough. Prepared for the Ecological LandClassification Working Group) provide the regionalecological context within which the remainder of thisreport is structured. A summary of these approaches,described by ecoregion, follows.

The Boreal (West and East)Forest Region (ecoregions 3E, 2W,3W, 4W, 3S, 4S, 5S) Analysis for ecosite-specific old growth definitions wasbased on a dataset with 2312 sample plots fromvarious sources. The sources include growth and yieldplots, ecosystem classification plots and Morawski cullplots covering a wide range of ecosystems and species(Appendix B). Data were derived from undisturbedmature forest conditions. Age-of-onset and durationof old growth characteristics were estimated.

Age-of-onsetThis is a stand-level estimate of the minimum age-of-onset for species/ecosite combinations to enter an oldgrowth condition. The analysis was designed to seeksize and structural transition points for each forestspecies and ecosystem. With the soil, site and floristicinformation already embedded in the ecosystemclassification, it was possible to sort the various plotdatabases by specific conditions and examine growthrelationships and trends in mortality. Age-of-onset wascalculated by determining the minimum age at whichthe various species that normally occur attain at least75 per cent of their maximum potential diameter (foran ecosite or forest unit) and make up more than 50per cent of the stand basal area. In other words, thestand reaches the age-of-onset for old growth when itbegins to be dominated by trees approaching theirmaximum sizes and ages. This approach captures themain characteristic of old growth conditions, namely,that the normally occurring, dominant species achievethe maximum size possible for the site conditions.

In addition to age and diameter data, the percentageof rot in the main stem, changes in stand height and

Figure 3Levels of integration in ecological land classification:ecoregional, site and chronological(adapted from Meidinger and Pojar 1991)

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patterns of mortality were used as further indicators of

the age-of-onset. See Appendix C for details. Results

are presented on an ecosite and tree species basis.

Alternative combinations of height, diameter and

basal area or dominance were also examined. Values

presented in the following matrices significantly refine

the minimum age for old growth previously reported.

Duration This estimate of the duration or persistence of old

growth conditions is based on the difference between

the age-of-onset and the age at which the various

possible dominant species cease to occupy at least 30

per cent of the stand basal area. Duration was initially

calculated from the maximum ages attained, by

species and ecosite, across the range of collated plots.

In addition, results of growth and yield literature,

mortality data, successional studies, forest fire

frequency records and expert opinion regarding the

maximum achievable age for a tree species on a given

site were used to further refine the estimated duration.

The Great Lakes-St. LawrenceForest Region (ecoregions 4Eand 5E)

Age-of-onsetFor this analysis, a database was assembled from 2696

forest ecosystem classification, growth and yield, and

Morawski et al. (1958) cull survey plots from the Great

Lakes-St. Lawrence Forest region of central Ontario.

Although the landscape in this region has a long history

of human disturbance, all plots included in the analyses

were selected on the basis of a minimum of human

impact. The database contained information on species

Pw-Pr-Bw (Po)Pr-Pw (Pj) Pj-Sb (Bf-Bw) Sb-Bw (Pj) Sb (L) Sb

Ecosite:

Name:

Vegetation type:

Name:

Soil type:

Name:

Moisture regime:

ES11

V12

SS3 SS6 S3 S8 S12F S12S

V13 V18 V20 V34 V38

Red Pine-White Pine-Jack Pine:Very Shallow Soil

White PineMixedwood

Very ShallowSoil on Bedrock

Shallow-ModeratelyDeep/Coarse Loamy

Fresh/CoarseLoamy

Moist/CoarseLoamy

Wet/Organic(Feathermoss)

Wet/Organic(Sphagnum)

Red PineMixedwood

Jack PineMixedwood/Feathermoss

Black SpruceMixedwood/Feathermoss

Black Spruce/Labrador-tea/Feathermoss(Sphagnum)

Black Spruce/Leatherleaf/Sphagnum

Dry

ES18

Red Pine-White Pine:Fresh, Coarse Loamy Soil

Dry-Fresh

ES20 ES22

Spruce-Pine/Feathermoss:Fresh, Sandy-Coarse Loamy Soil

Spruce-Pine/Ledum/Feather-moss: Moist, Sandy-CoarseLoamy Soil

Fresh Moist

ES35 ES34

Poor Swamp:Black Spruce:Organic Soil

Treed Bog:Black Spruce/Sphagnum:Organic Soil

Wet Wet

Figure 4Example topographic sequence showing typical arrangement of ecosites. Comprised of ecologically and spatiallyrelated vegetation and soil types, ecosites provide the basis for the old growth forest definitions in this report. Ecositesalso serve as the basis for the spatial inventory data used in the old growth mapping exercises. (Arnup et al. 1999)

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and diameter at breast height (DBH) for every tree andage at breast height for a sub-sample of trees per plot.Each plot was classified in the appropriate ecosite usingsoil and vegetation data collected from the plot. Thesedata were analyzed separately from those of the Borealportions of Ontario due to differences in plot sizes,variables and ecological considerations.

Initially, the analytical approach used in the BorealForest region was attempted, but it did not yieldecologically reasonable results. As an alternative,regression models describing the relationship betweenage and DBH were developed for all speciescomprising greater than 10 per cent of the plot basalarea. Preliminary estimates of age-of-onset for eachmajor species were then determined to be when thepredicted DBH was approximately 85 to 90 per cent ofthe maximum DBH attainable by the species on agiven range of ecologically similar ecosites.

Duration A modified version of the analysis used in Boreal Forestareas to estimate the duration of old growthconditions was attempted. The lower end of theduration period was defined as the mean age of allplots whose age is greater than the age-of-onset (plus 1standard deviation) for a species on an ecosite. Theupper end of the duration period was defined as threestandard deviations above that value or the age of theoldest plot.

For some species, there were insufficient data todevelop a reasonable estimate for the duration period.These species are noted in the matrix as having“Insufficient (Insuf.) data.” The duration period shownfor some species is greater than 500 years. Unlike themajority of Boreal communities, a number of speciescommon in these ecosystems (sugar maple, yellowbirch, hemlock and beech) are very long-lived. Theyare capable of self-perpetuation through single tree ormulti-tree gap phase replacement processes that resultin a substantially longer presence on the landscapebetween catastrophic events.

The Deciduous Forest Region(ecoregions 6E and 7E)Old growth estimates for ecosites in the DeciduousForest region (ecoregions 6E and 7E) were based on areview of literature and expert opinion. Data from thefirst approximation of the ELC framework forsouthern Ontario (Lee et al. 1998) and growth andyield plots were also used. Plot data from old growthconditions are not common in southern Ontario. Agerelationships for the available data indicated that veryfew of the plots approached either the maximum sizeor the maximum age for these ecological conditionswhen compared to the literature. The lack of oldgrowth in forest stands in southern Ontario, asdiscussed earlier and as evidenced by queryingavailable survey data, made it impractical to pursueany kind of quantitative analysis at this time. As aresult, age-of-onset for old growth, life expectancyestimates and estimates of old growth duration wereobtained from the literature, expert opinion,predictive growth and yield curves, and a partial use ofthe ELC dataset.

The recent publication by Larson et al. (1999), TheWoodland Heritage of Southern Ontario, has addedgreatly to the understanding of remnant natural forestconditions in the highly populated portions of theprovince. These results have been incorporated whereappropriate. Work is ongoing to improve sampling inforests of varying ages across southern Ontario.

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R e s u l t s a n d D i s c u s s i o n

Results and Discussion

Tables 1-4 summarize old growth characteristicsby ecosite (or combinations of ecologicallysimilar ecosites) for forest regions of Ontario.

Each table includes a short description of thedominant overstory and understory vegetation andassociated soil and site conditions. All tables includeage-of-onset and duration, except for the DeciduousForest region, where tree-level life expectancy data areused to approximate stand-level duration.

The Boreal-West Forest Region(ecoregions 2W, 3W, 4W, 3S, 4S, 5S)The relationship between site condition and the age-of-onset of old growth is illustrated in Table 1. Thegeneral trends agree with the results of Woods andBeckwith (1987). Highly productive (Site Class 1A, 1and 2) black spruce stands enter the old growthcondition earlier than Site Class 3 black spruce stands.The latter stands grow more slowly, achieving theirmaximum size at a later age. Persistence as living trees(duration) is observed to be greater on sites with lowerproductivity. This trend also agrees with theobservations of Iles (1990), Arbex (1991) and Carletonand Arnup (1993).

Across all ecosites, poplar and balsam fir have lowerage-of-onset than other species. In contrast, white andred pine and white spruce have higher age-of-onsetthan other species. These findings are consistent withthe individual ecology of the trees involved; thoseecosites capable of producing large diameter boles andlasting many years have higher age-of-onset thanthose with a relatively short lifespan.

As an ecosite becomes less favourable for maximumgrowth rates, the age-of-onset increases. Trees takelonger to grow to a point where the average standdiameter at breast height reaches at least 75 per cent ofthe maximum for a given combination of site andspecies. For example, on upland ecosites black spruceage-of-onset ranges from 100 to 120 years, but onnutrient poor, low-productivity wet organic ecosites(ecosites 34, 35) age-of-onset is delayed to 160 years.

Of particular interest is the age-of-onset of 100 yearsfor poplar on ecosite 12. This age is surprisingly high,

especially for the western portion of the northwestregion, where the macroclimate is drier and growthconditions are viewed as less favourable for poplarcompared to areas further east. Experience has shownthat many poplar stands on ecosite 12 in the Kenoraarea break up much earlier than 100 years – many asearly as 70 years of age. Additional work is required tofully explain sub-regional variations in stand mortalityand mortality patterns, and resulting impacts on theage-of-onset (examples Perala and Ciezewski 1999).

Currently, few quantitative data exist for mortalitytrends and stand-structural changes through time (i.e.,stand physiognomy, downed woody materials andsuccession). Mortality data derived from Morawski’scull surveys of the late 1950s support the initialmorbidity/mortality trends observed in the compiledgrowth and yield datasets. A non-quantitative reviewof the ecosystem classification plot data and fact sheetinformation compiled for each regional classificationindicates increasing structural diversity with increasingage, which can also be attributed to tree mortality andstand break-up. Initial studies using quantitativeecosystem data to examine successional trendsindicate that some ecosites develop greater stand-structural diversity over time (Kenkel et al. 1998). Thelandscape does show a trend to converge on a numberof types, represented by a limited set of ecosites. This isnot to suggest that these are self-perpetuating climaxconditions. Rather, in the fire-dominated Borealportions of Ontario, certain ecosites best capture thestructural complexity and diversity associated with oldgrowth, late-successional conditions. Readers arereferred to Kenkel et al. (1998) and related literature(Carleton and Maycock 1978; Cogbill 1985) for a morecomprehensive discussion. This area of study requiresmore investigation.

Historical patterns of catastrophic disturbance andopportunistic life-history strategies of the forest treespecies typical of the Boreal Forest region wouldsuggest in most cases a relatively short duration forold growth conditions. These disturbances andstrategies would minimize opportunities for majoraccumulations of dead and downed woody materialand other structural legacies associated with oldgrowth conditions. However, recent data suggestnatural fire regimes may be lengthening due to firesuppression or climate change in many areas. It ispossible that the duration of old growth in Boreal

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A n E c o l o g i c a l C o n t e x tf o r O n t a r i o F o r e s t s

Forest regions may well extend beyond that suggestedin the current data (Bergeron et al 2000a).

The Boreal-East Forest Region(ecoregion 3E)The trends in old growth age-of-onset in the Boreal-East Forest region are very similar to those in theBoreal-West Forest region. A cooler and more humidregional climate results in a somewhat longer fire-return interval and differences in species and ecositeassemblages. The landbase exhibits higher proportionsof black and white spruce than those found in thewestern portions of the province, as well as a variety ofBoreal mixedwood conditions.

Ecosites with higher fertility exhibit the same trendof higher productivity, greater variety of plant speciesand earlier onset of old growth conditions. Ecositesthat are drier, shallow and less fertile reach theirmaximum sizes more slowly. They exhibit lower standdensities and less complex community composition,but do tend to persist for longer time periods, barringthe occurrence of catastrophic disturbance.

The Great Lakes-St. LawrenceForest Region (ecoregions 4Eand 5E)In most cases, the revised old growth estimates for theGreat Lakes-St. Lawrence Forest region exceed thosein the final report of the Old Growth Forests PolicyAdvisory Committee (MNR 1994). The committee’sestimates were based on expert opinion. Analysis ofthe 2696 sample plots compiled for this portion of theGreat Lakes-St. Lawrence Forest region, combined withother studies, has refined these original estimates.

Of particular interest is the persistence of tree speciesover time in the long-lived tolerant hardwood forestecosites. The long period of time between catastrophicstand-replacing disturbances and the more commonfine-scale disturbance regimes typical of the region hasresulted in more complex age and physical structuresin many of these forests. Old growth characteristicsmay persist for centuries (Arbex 1991, Iles 1990,Carleton and Arnup 1993, Frelich and Graumlich1994, Tyrell and Crow 1994, Frelich and Reich 1995,1996). In contrast to much of the Boreal Forest region,

the forest systems of the Great Lakes-St. LawrenceForest region are expected to develop complex multi-cohort age structures in most instances of old growthconditions. Due to the lower frequency of intenseforest fires, accumulations of dead and downed woodymaterial are also expected to be more significant thanin the Boreal Forest region.

The Deciduous Forest Region(ecoregions 6E and 7E)The old growth estimates for the most southernportion of the province are primarily based onliterature from southern Ontario as well as theadjacent Great Lakes and northeastern US states. TheELC and growth and yield datasets were also queriedfor maximum age estimates for tree species. Theoriginal estimates in the final report of the OldGrowth Forests Policy Advisory Committee (MNR1994) were supplemented with results from morerecent surveys of remnant old forest in the south. Oneexample is the investigation of old growth easternwhite cedar systems on the cliffs of the NiagaraEscarpment by Larson and Kelly (1991). Resultspresented in Table 4 correspond closely with thosediscussed in Larson et al. (1999).

Comprehensive studies of old growth are lacking forsouthern Ontario. The extensive deforestation foragriculture and urban development has reduced forestcover in some areas of southwestern Ontario to less thanfive per cent of the landbase. References from adjacentGreat Lakes states are not entirely adequate forcomparison. However, work by Abrams and Downs(1990), Abrell and Jackson (1977), Martin (1977),Bormann and Buell (1964), Barnes (1989) and numerousothers support the general trends outlined here.

Sampling is still taking place in the forests of southernOntario. It is hoped that the additional informationwill improve the current quantitative estimates in thevery near future.

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ES 11, ES 15

White Pine, RedPine

Pw – 150Pr – 130

Pw – 150Pr – 110

Very shallow (<20 cm)soils with bedrockoutcrops (ES 11), to dry, well drained coarse to finesandy soils (ES 15)

Conifer dominated, with Pw, Pr. Po, Bw, Pj and Sw may occur.Ce may be locally abundant. Shrub and herb poor.

Jack Pine, BlackSpruce,(Trembling Aspenin patches)

ES 12 Pj – 110Sb – 120Po – 100

Pj – 60Sb – 50Po – 40 to 60

Very shallow (<20 cm)soils with bedrockoutcrops

Conifer dominated, with Pj and Sb. Po and Bf may occur. Shruband herb poor. Ground cover of bedrock, conifer litter, lichensand feathermosses.

Jack PineES 13 Pj – 110 Pj – 70Dry to moderately fresh,rapidly to well drained,coarse to fine sandy soils

Conifer dominated, with Pj, Sb sparse to abundant. Ofteneven-aged. Bw and Po may occur. Ground cover offeathermosses, that are abundant under closed canopy, butmay be replaced by lichens under open canopy.

Jack Pine, BlackSpruce, (Mixturesof TremblingAspen, and WhiteBirch)

ES 14 Pj – 110Sb – 120Po – 90

Pj – 90Sb – 60Po – 30 to 50

Dry to moderately fresh,rapidly to well drained,coarse to fine deep sandysoils

Conifer dominated, with Pj and/or Sb. Po can be dominant. Bwand Bf may occur. Typically abundant shrubs and herbs.Ground cover of feathermosses, conifer and deciduous litter.

Trembling Aspen,White Birch,Balsam Fir

ES 16 Po – 100Bw – 110Bf – 70

Po – 50Bw - 30Bf – 40 to 60

Dry to moderately fresh,rapidly to well drained,coarse to fine deep sandysoils

Dominated by Po, Bw and Bf. Sw, Sb and Pj may occur. Thedeciduous component exceeds 50 per cent of the canopy.Typically shrub and herb rich. Ground cover of deciduous andconifer litter and wood.

White Cedar ES 17 Ce – 100 Ce – 100 Wide range of upland soilconditions

Ce dominated conifer and mixedwood stands. Shrubs includeBf, Ce and mountain maple. Ground cover of conifer anddeciduous litter, feathermosses and wood.

White Pine, RedPine

ES 18, ES 24

Pw – 140Pr – 130

Pw – 160Pr – 120

Fresh, well drained,coarse loamy to fineloamy soils

Conifer dominated, with Pr and Pw. Occasionally with Po, Bw,and/or Bf. Shrubs include mountain maple and beaked hazel.Ground cover consists of conifer and deciduous litter,feathermosses and wood.

Trembling Aspen,White Birch,Balsam FirMixedwood

ES 19 Po – 100Bw – 110Bf – 70Pj – 90

Po – 30 to 70Bw – 30Bf – 40 to 60Pj – 30 to 70

Fresh, well drained, finesandy to coarse loamysoils

Mixedwood, dominated by Po, Bw and Bf. Sw and Sb mayoccur. Deciduous tree component exceeds 50 per cent of thecanopy. Shrub and herb rich.

Black Spruce, JackPine

ES 20 Sb – 120Pj – 110

Sb – 50Pj – 60

Dry to fresh, rapidly towell drained, fine to coarsesandy or coarse loamy

Conifer dominated with Sb and Pj. Po, Bw and Bf may occur.Usually shrub and herb poor. Ground cover of feathermossesand conifer litter.

Balsam Fir, WhiteSpruce, BlackSpruce (Mixturesof Trembling Aspenand White Birch)

ES 21 Bf – 70Sw – 130Sb – 120Po – 90

Bf – 40 to 60Sw – 50 to 70Sb – 30 to 60Po – 80

Fresh well drained coarseloamy soils

Conifer dominated with Bf, Sw and Sb. Po and Bw may occur.Coniferous component exceeds 50 per cent of the canopy.Typically shrub and herb poor. Ground cover of feathermosses.


ES 22 Sb – 120Pj – 110

Sb – 30 to 60Pj – 20 to 40

Moist, sandy to coarseloamy soils

Conifer dominated with Sb and Pj. Po, Bw, Sw and Bf mayoccur. Moderately shrub and herb poor. Ground cover offeathermosses, conifer litter and Sphagnum spp.

Trembling Aspen,White Birch,Balsam Fir

ES 23 Po – 90Bw – 100Bf – 70

Po – 30 to 60Bw – 40Bf – 40 to 60

Dominated by Po, Bw, Bf. Sw, Sb and Pj may occur. Deciduoustree component exceeds 50 per cent of the canopy.Moderately shrub and herb rich. Ground cover of deciduousand conifer litter, feathermosses and Sphagnum patches.

Moist, sandy to coarseloamy soils

TABLE 1: OLD GROWTH AGE-OF-ONSET AND DURATION FOR FOREST*Ecosites in Ecoregions 2W, 3W, 4W, 3S, 4S, 5S (Boreal-West Forest Region)

General SpeciesAssociations

Ecosites Common Soil and SiteDescription

Associated Vegetation and Stand Structure Characteristics

Old GrowthAge-of-Onset(yrs)

Old GrowthForest StandDuration (yrs)

*Refer to page 24 for a full list of acronyms and general species associations.


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Trembling Aspen,Black Ash

ES 29, ES 30

Po – 100Ab – 100

Po – 50Ab – 20 to 50

Ranges from freshmoderately well to welldrained, fine loamy–clayeyto fresh to moist, well toimperfectly drained, siltyto clayey soils

Dominated by Po and /or Ab. Bw, Pb, Ce may occur on ES 30.Bw, Bf, Sw, Sb, and Pj can occasionally occur on ES 29. Shruband herb rich. Ground cover of deciduous and conifer litter,feathermosses and wood.


ES 31 Sb – 120Pj – 110

Sb – 30 to 40Pj – 50

Moist, silty to clayey soils Conifer dominated with Sb and Pj. Po, Bw, Pb, Sw and Bf mayoccur. Shrub and herb poor. Ground cover of Sphagnum inwetter locations.

Balsam Fir, WhiteSpruce, TremblingAspen, BalsamPoplar

ES 32, ES 33

Bf – 80Sw- 110Po – 100Pb – 90

Bf – 20 to 30Sw – 20 to 90Po – 40Pb – 30 to 40

Moist, imperfectly topoorly drained, silty toclayey textured

Mixedwood, dominated by Bf, Sw, Sb and Po. Bw, Pj and Pbmay occur. Moderately shrub and herb rich. Ground cover ofdeciduous and conifer litter, feathermosses and wood.

Black Spruce(Treed Wetland)

ES 34, ES 35

Sb – 160 Sb – 190+Wet organic soils, withsphagnum peat usuallydeeper than 40 cm (maybe shallower at marginsof peatlands)

Sb. dominated wetlands. Ericaceous shrubs and sedgespresent. Ground cover of Sphagnum with patches offeathermosses and conifer litter.

Black Spruce(Tamarack)(ForestedWetland)

ES 36 Sb – 100La - 100

Sb – 250+La - insuf.Data

Wet organic soils (woodyor Sphagnum peat)

Conifer dominated wetlands with Sb, often with La, Bf or Ce.Understorey includes speckled alder. Moderately shrub, herband moss rich. Ground cover of feathermosses, Sphagnum,conifer and deciduous litter.

White Cedar(ForestedWetland)

ES 37 Ce – 140La – 100

Ce – 210+La - insuf.Data

Wet organic or peatyphase soils

Ce. dominated wetlands. La, Sb, Bf and Sw may occur. Shrubsinclude mountain maple and speckled alder. Herb rich. Groundcover of feathermosses, conifer litter, Sphagnum and wood.

Black Ash, OtherHardwood(includes ForestedWetlands)

ES 38 Ab – 100Po – 80Pb – 80

Ab – 50Po – 60 to 80Pb – 10 to 50

Moist mineral to wetorganic soils, may havesmall permanent pools

Hardwood dominated with Ab and/or Ew. Po, Pb, may occur.Often shrub, herb and graminoid rich. Ground cover ofdeciduous litter, logs and mosses.

Jack Pine, BlackSpruce

ES 25 Pj – 100Sb – 110

Pj – 50Sb – 20 to 50

Fresh, well to moderatelywell drained silt to siltloam

Conifer dominated with Pj and Sb. Po, Bw and Bf may occur.Typically shrub and herb poor in young fire origin stands, mayvary to shrub and herb rich. Ground cover of feathermossesand conifer litter.


ES 26 Sb – 120Pj – 110

Sb – 60Pj – 20 to 40

Fresh, well to moderatelywell drained, fine loamyto clayey soils

Conifer dominated with Sb and Pj. Po, Bw and Bf may occur.Typically shrub and herb poor. Ground cover offeathermosses, conifer litter and wood.

Balsam Fir, BlackSpruce, WhiteSpruce (Mixturesof TremblingAspen and WhiteBirch)

ES 27 Bf – 70Sw – 100Sb – 100Po – 100

Bf – 30Sw – 50 to 100Sb – 50Po – 40 to 60

Fresh, well to moderatelywell drained, silty to fineloamy soils

Conifer dominated with Bf, Sb and Sw. Po and Bw may occur.Typically shrub and herb rich. Ground cover of deciduous andconifer litter, feathermosses and wood.

Trembling Aspen,White Birch

ES 28 Po – 100Bw – 100

Po – 30Bw – 40

Fresh, well to moderatelywell drained silt to siltloam

Dominated by Po and Bw. Bf, Sb, Sw and Pj may occur.Deciduous tree component exceeds 50 per cent of thecanopy. Shrub and herb rich. Ground cover of deciduous andconifer litter, feathermosses and wood.

TABLE 1: OLD GROWTH AGE-OF-ONSET AND DURATION FOR FOREST cont’d*Ecosites in Ecoregions 2W, 3W, 4W, 3S, 4S, 5S (Boreal-West Forest Region)






*Refer to page 24 for a full list of abbreviations and general species associations.

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Jack Pine, BlackSpruce, WhiteSpruce

ES 1p, 1r Pj – 100Sb – 90Sw – 110

Sb – 80 to 90Pj – 80Sw – 20 to 70

Very shallow soils Conifer dominated, with Sb, Pj, Sw. Bw, Bf and Po may occur.Shrubs include blueberries, bush honeysuckle, creepingsnowberry, and mountain maple. Typically shrub and herbpoor. Ground cover of bedrock, conifer and deciduous litter,feathermosses and lichens.

Jack PineES 2 Pj – 110 Pj – 60 to 80Dry to fresh sandy soils Conifer dominated, with Pj. Sb may occur. Shrubs includeblueberries, twinflower, sheep laurel and black spruce. Shruband herb poor. Ground cover of feathermosses and lichens.

Jack Pine, BlackSpruce, WhiteBirch, TremblingAspen, Mixedwood

ES 3 Pj – 110Sb – 80Po – 80Bw – 90

Pj – 60 to 80Sb – 40Po – 50Bw – 80 to 90

Dry to moist, sandy tocoarse loamy soils

Mixedwoods, with Pj, Sb, Bw and Po. Bf and Sw may occur.Typically shrub and herb poor. Ground cover of deciduouslitter, feathermosses and lichens.

Jack Pine, BlackSpruce

ES 4 Pj – 100Sb – 90

Pj – 60 to 70Sb – 60 to 80

Dry to moist, sandy tocoarse loamy soils

Conifer dominated, with Pj and Sb. Sub-canopy of Sb. Shrubsinclude blueberries, creeping snowberry, labrador tea. Groundcover of feathermosses.


ES 5f,5m

Sb – 110Pj – 90

Sb – 100Pj – 40

Fresh to moist, mediumloamy to clayey soils

Conifer dominated, with Sb and Pj. Shrub and herb poor.Ground cover of feathermosses.

Trembling Aspen,Black Spruce,Balsam Fir,Mixedwood

ES 6f,6m

Po – 90Sb – 110Bf – 70

Po – 40 to 60Sb – 60Bf – 20 to 30

Fresh to moist, mediumloamy to clayey soils

Mixedwoods, with Po, Sb and Bf. Sw may occur. Shrubsinclude currants, honeysuckles, bristly wild rose and dwarfraspberry. Herb rich. Ground cover of deciduous andconiferous litter and feathermosses.

Trembling Aspen,Black Spruce, JackPine Mixedwood

ES 6c Po – 80Sb – 90Pj – 90

Po – 30 to 50Sb – 40 to 60Pj – 60 to 80

Dry to moderately moist,sandy to coarse loamysoils

Hardwood dominated mixedwoods, with Po, Sb, and Pj.Shrubs include bush honeysuckle, blueberries, twinflower anddwarf raspberry. Ground cover of deciduous and coniferouslitter and feathermosses.

Trembling Aspen,White Spruce,Balsam Fir,

ES 7f,7m

Po – 100Sw – 120Bf – 70

Po – 50Sw – 50 to 80Bf – 20 to 30

Fresh to moist, fine loamyto clayey soils

Hardwood dominated mixedwoods, with Po, Sw and Bf.Shrubs include dwarf raspberry, mountain maple and beakedhazel. Herb rich (7f). Ground cover of deciduous andconiferous litter and feathermosses.

Trembling Aspen,Black Spruce,White Spruce

ES 7c Po – 110Sb – 120Sw – 120

Po – 40 to 60Sb – 20 to 40Sw – 60 to100

Dry to moderately moist,sandy to coarse loamysoils

Hardwood dominated mixedwoods, with Po, Sb and Sw.Shrubs include mountain maple, bush honeysuckle and beakedhazel. Ground cover of deciduous and coniferous litter andfeathermosses.

Black SpruceES 8 Sb – 100 Sb – 60Moist sandy to clayeysoils

Conifer dominated, with Sb. Herb and shrub poor. Groundcover of feathermoss and Sphagnum spp.

TABLE 2: OLD GROWTH AGE-OF-ONSET AND DURATION FOR FOREST*Ecosites in Ecoregion 3E (Boreal-East Forest Region)

Black SpruceES 9p Sb – 110 Sb – 60 to 70Moist Sandy to clayeysoils

Conifer dominated, with Sb. Shrubs include ericaceous species,dwarf raspberry, mountain maple, currants. Ground cover offeathermoss and Sphagnum spp.

White Spruce,Balsam Fir, WhiteCedar

ES 9r Sw – 100Bf – 70Ce – 100

Sw–40 to 100Bf – 60Ce – 30 to 70

Moist sandy to clayeysoils

Conifer dominated, with Sw, Bf and Ce. Shrubs includeericaceous species, dwarf raspberry, mountain maple,currants. Herb rich. Ground cover of feathermosses,deciduous and conifer litter.








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TABLE 2: OLD GROWTH AGE-OF-ONSET AND DURATION FOR FOREST cont’d*Ecosites in Ecoregion 3E (Boreal-East Forest Region)

Trembling Aspen,Balsam Poplar,Black Spruce,

ES 10 Po – 80Pb – 80Sb – 100Ab – 100

Po – 60 to 70Pb – 30Sb – 40Ab – 50

Moist sandy to clayeysoils, Hi/Ah surfacehorizons

Hardwood dominated mixedwoods, with Po, Pb and Sb.Shrubs include dwarf raspberry, speckled alder and currants.Herb rich. Ground cover of deciduous and conifer litter andfeathermosses.

Black Spruce(treed )

ES 11 Sb – 140 Sb – 210+Wet deep fibric organicsoils

Conifer dominated wetlands dominated by Sb. Ericaceousshrubs including labrador tea, leatherleaf, bog laurel andblueberries. Herb poor. Ground cover of Sphagnum spp. andfeathermosses.

Black Spruce,(forested wetland)

ES 12 Sb – 110 Sb – 240+Wet deep fibric and mesicorganic soils

Conifer dominated wetlands dominated by Sb. Shrubs includelabrador tea, speckled alder and blueberries. Herb poor.Ground cover of sphagnum and feathermosses.

Black Spruce,Larch, WhiteCedar (forestedwetland)

ES 13p,13r

Sb – 120La – 110Ce – 140

Sb – 230+La – insuf.dataCe – 210+

Wet moderately deepfibric (13p), or shallowfibric, mesic or humicorganic soils (13r)

Conifer dominated wetlands dominated by Sb, La, and Ce.Shrub and herb rich. Ground cover of Sphagnum spp. andfeathermosses.

Black Spruce(treed wetland)

ES 14 Sb – 150 Sb – 200+Wet deep fibric organicsoils

Conifer wetlands dominated by Sb. Shrubs include labradortea, leatherleaf, bog rosemary and bog laurel. Ground cover ofSphagnum spp. and feathermosses

White Pine, RedPine and WhiteSpruce

ES 18,19, 20,21

Pw – 130Pr – 130Sw – 100

Pw – 100 to170Pr – 70 to 120Sw – 100 to120

Dry to fresh, sandy tocourse loamy

Conifer dominated with Pw, Pr, and Sw. Shrubs includemountain maple and beaked hazel. Ground cover of coniferlitter.

HardwoodMixedwood(Yellow Birch,Hard Maple, SoftMaple, TremblingAspen, WhiteBirch, and WhiteSpruce)

ES 15,16, 17

By – 150Mh – 140Ms – 80Po – 80Bw – 90Sw – 90

By – 500+Mh – 500+Ms – 40 to 80Po – 50Bw – 20 to 40Sw – 60

Dry to moist, rocky tosilty soils

Hardwood stands dominated by By, Mh, Ms, Bw, Po. Sw mayoccur. Shrubs include mountain maple, beaked hazel andCanada fly honeysuckle. Ground cover of deciduous litter.







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White Pine,Red Pine,Poplar, JackPine, Red Oak

ES 11 -14 Pw – 150Pr – 140Or – 110Po – 100Pj – 90

ES11– 130ES12– 140ES13– 120ES14– 120

ES11–60 to 120ES12–60 to 110ES13–50 to 100ES14 – 60 to 120

Pw – 80 to 160Pr – 50 to 100Or – 70 to 140Po – 40 to 80Pj – 30 to 50

Dry to fresh, veryshallow to deep,sandy to coarseloamy soils

Conifer dominated. White spruce and balsam fircan be minor components of overstory. Shrubsinclude beaked hazel, blueberry spp., bushhoneysuckle, fly honeysuckle, serviceberry spp.,twinflower, and wintergreen. Low to moderatenumber of herbs. Ground cover of feathermosses.

Black Spruce,Jack Pine,White Pine,Red Pine

ES 15 &16

Pw – 150Pr – 140Pj – 100Sb – 100

ES15– 100ES16 –110

ES15 – 30 to 50ES16 – 40 to 70

Pw – 80 to 160Pr – 50 to 100Pj – 30 to 50Sb – 30 to 50

Dry to fresh, veryshallow to deep,sandy to coarseloamy soils

Conifer dominated. Poplar and white birch canbe minor components of overstory. Shrubsinclude blueberry spp., bush honeysuckle,creeping snowberry, labrador tea, sheep laurel,trailing arbutus, and twinflower. Herb poor.Ground cover of feathermosses and lichens.

Poplar, WhiteBirch, WhiteSpruce, BalsamFir, Jack Pine,Black Spruce,Soft Maple

ES 17-19 Sw – 110Sb – 100Bw – 90Po – 90Pj – 80Bf – 70Ms – 70

ES17 – 90ES18–100ES19 – 90

ES17 – 40 to 70ES18 – 40 to 70ES19 – 40 to 70

Sw – 60 to 130Sb – 30 to 50Bw – 40 to 80Po – 30 to 50Pj – 30 to 50Bf – 40 to 80Ms – insuf. data

Dry to moist, deep,sandy to coarseloamy soils

Hardwood-dominated mixedwoods. Shrubsinclude beaked hazel, blueberry spp., bushhoneysuckle, fly honeysuckle, mountain maple,twinflower, and wild raisin. Moderate number ofherbs. Ground cover of feathermosses and lichens.

White Pine,White Cedar,White Birch,White Spruce,Balsam Fir, RedPine, Poplar

ES 20 -22 Pw – 150Pr – 140Ce – 120Sw – 110Bw – 90Po – 90Bf – 70

ES20– 140ES21–120ES22–110

ES20 – 60 to 120ES21 – 60 to 120ES22 – 50 to 110

Pw – 80 to 160Pr – 50 to 100Ce – 70 to 140Sw – 60 to 130Bw – 40 to 80Po – 30 to 50Bf – 40 to 80

Dry to moist, veryshallow to deep,sandy to coarseloamy soils

Conifer-dominated mixedwoods. Shrubs includebeaked hazel, blueberry spp., bush honeysuckle,creeping snowberry, mountain maple, flyhoneysuckle, showy mountain-ash, andtwinflower. Moderate number of herbs. Groundcover of feathermosses, Sphagnum, and lichens.

Hard Maple,White Birch,Poplar, RedOak, WhitePine,Basswood,AmericanBeech

ES 23 -27 Pw – 150Be – 150Mh – 140Bd – 120Or – 120Bw – 100Po – 90

ES23–110ES24– 120ES25–130ES26–130ES27–120

ES23 > 300ES24 > 400ES25 > 500ES26 > 500ES27 > 300

Pw – 80 to 160Be – > 500+Mh – > 500+Bd – 40 to 80Or – 50 to 110Bw – 40 to 80Po – 30 to 50

Dry to fresh, deep,sandy to coarseloamy soils, oftencalcareous

Tolerant and mid-tolerant hardwood dominated.Black ash, black cherry, ironwood, soft maple, yellowbirch, and white ash minor components of theoverstory. Shrubs include alternate-leaved dogwood,beaked hazel, fly honeysuckle, leatherwood, maple-leaved viburmum, mountain maple, striped maple,and partridgeberry. Low to moderate number ofherbs (but rich in spring ephemerals). Ground coverof ragged and hypnum mosses and lichens.

EasternHemlock,Hard Maple,Yellow Birch,White Cedar,Soft Maple

ES 28– 30 He – 180By – 160Mh – 140Ce – 120Ms – 100

ES28– 150ES29– 140ES30–160

ES28 > 500ES29 > 500ES30 > 500

He – > 500+By – > 500+Mh – > 500+Ce – 70 to 140Ms – 40 to 80

Dry to moist,shallow to deep,sandy to mediumloamy soils

Tolerant hardwoods and mixedwoods. Beech,poplar, white spruce minor components of theoverstory. Shrubs include beaked hazel, flyhoneysuckle, hobblebush, mountain maple, andstriped maple. Low to moderate number ofherbs. Ground cover of polytrichum and hypnummosses, liverworts, and lichens.

Black Spruce,White Cedar,Larch, BalsamFir

ES 31-33 Ce – 150Sb – 110La – 90Bf – 70

ES31– 110ES32– 120ES33–130

ES31– Insuf. dataES32 – Insuf. dataES33 – Insuf. data

Ce – Insuf. dataSb – Insuf. dataLa – Insuf. dataBf – 40 to 80

Very moist to wet,deep, mineral andorganic soils

Conifer dominated. Shrubs include blueberryspp., creeping snowberry, labrador tea, mountainholly, mountain maple, sheep laurel, showymountain - ash, speckled alder, twinflower, andwild raisin. Low to moderate number of herbs.Ground cover dominated by Sphagnum andfeathermosses.

Poplar, WhiteCedar, BlackAsh, SoftMaple, YellowBirch, HardMaple

ES 34&35 Ce – 150By – 150Mh – 130Ab – 120Ms – 90Po – 80

ES34–120ES35– 120

ES34–Insuf.dataES35–Insuf.data

Ce – Insuf. dataBy – > 500+Mh – > 500+Ab – 50 to 100Ms – 40 to 80Po – Insuf. data

Very moist, deep,coarse loamy toorganic soils

Hardwood dominated. Shrubs include alternate-leaved dogwood, beaked hazel, choke cherry,dwarf raspberry, fly honeysuckle, mountainmaple, red currant, and wild red raspberry.Herb rich.

TABLE 3: OLD GROWTH AGE-OF-ONSET AND DURATION FOR FOREST*Ecosites in Ecoregions 4E and 5E (Boreal-East Forest Region)



Overstory Species

Ecosites Common Soil andSite Description

Associated Vegetation and Stand StructureCharacteristics

Species-specific Old GrowthAge-of-Onset(yrs)

Ecosite-specificOld GrowthAge-of-Onset(yrs)

Ecosite-specific Old GrowthDuration(yrs)

Species-specificOld GrowthDuration (yrs)

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White Pine, RedPine, Jack Pine

FOC1 Pw – 120 Pw– 450+Dry to fresh, shallow overbedrock, sandy to coarseloamy soils

Conifer dominated, with oak species; Ce, Bw, He, Bf, and Msmay occur; shrubs include blueberries, juniper, serviceberriesand sweet fern.

White Cedar, RedCedar

FOC2 Cr – 110Ce – 110

Cr – 500+Ce – 1000+

Dry to fresh, shallow overbedrock, sandy to coarseloamy soils

Conifer dominated, with oak and pine species; Iw and Hi mayoccur; shrubs include blueberries, bush honeysuckle andserviceberries; may be second growth on old farm fields.

White Cedar,Hemlock

FOC3,FOC4

Ce – 110He – 140

Ce – 1000+He – 600+

Fresh to moist, sandy tofine loamy soils

Conifer dominated; Pw, Bf and some hardwoods may occur.

Oak–Pine;Oak–Hardwood

FOM1,FOM2,FOD1

Or – 120Ow – 120Oblack – 120

Or – 200+Ow – 200+Oblack – 300+

Dry to fresh, shallow overbedrock, sandy to coarseloamy soils

Oak pine mixedwoods, Mh, Ms, Bd, Aw and Iw may occur(FOM1,2); Oak dominated with Or,Ow and/or Oblack (FOD1).

Tolerant–Mid–Tolerant Hardwoods

FOD4–6 Mh – 120Be – 120Tulip Tree –120Bd – 120

Mh – 200+Be – 300+Tulip Tree –300+Bd – 200+

Dry to moist, wide rangeof soil textures

Hardwood dominated, with any of Mh, Be, Iw, Bd, Ash, Oaks,Hi, Tulip Tree, Hackberry.

TolerantHardwood–ConiferMixedwood

FOM3–7 Mh – 120He – 140

Mh – 200+He – 600+

Dry to moist, wide rangeof soil textures

Mixedwoods with any of Mh, Ms, He, Or, Ce, Po, Bw and By.

Lowland–Transitional Deciduous

FOD7–9 Ash – 120 Ash – 200+Fresh to moist, sandy toclayey soils, often adjacentto riparian zones

Hardwood dominated, with Ew, Bd, Black Walnut, Sycamore,Ash, Po, Sassafras, Willows, Black Maple.

LowlandHardwoods andMixedwoods(forested wetlands)

SWD1–7,SWM1–6

Obur–120Msilver – 120Ash – 120

Obur – 200+Msilver – 200+Ash – 200+

Moist mineral, peaty phaseto wet organic soils

Hardwood dominated ecosites with Msilver, Ab, Ag, BlackWillow, Hackberry, Swamp White Oak, Bur Oak, Swamp Maple,Ew, By, Poplars; Mixedwoods with Ce and hardwoods (rich inherbs and ferns).

Lowland Conifers(forested wetlands)

BOT1,FET1,SWC1–4

Insuf. data Insuf. data Moist mineral, peaty phaseto wet organic soils

Conifer dominated wetlands, with Sb, L, Ce, Other Conifers;includes treed bogs (Sphagnum), fens (brown moss) orswamps (may be herb, fern and shrub rich)

TABLE 4: OLD GROWTH AGE-OF-ONSET AND DURATION FOR FOREST con’t.*Ecosites in Ecoregions 6E and 7E (Deciduous Forest Region)






*Refer below for a full list of abbreviations and general species associations.

Ax Ash (Mixed)Bd BasswoodBe BeechBf Balsam FirBw White BirchBy Yellow BirchCe CedarCr Red CedarEw White Elm

He HemlockIr IronwoodLa LarchMh Hard MapleMs Soft MapleMsilver MsilverOblack Black OakObur Bur OakOr Red Oak

Ow White OakPj Jack PinePo Poplar (Aspen)Pr Red PinePw White PineSb Black SpruceSw White Spruce

Abbreviations and General Species Associations

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Summary and Next Steps

This report presents ecosystem-based definitionsfor the age-of-onset and duration of old growthconditions in Ontario’s forests. It provides a

comprehensive and consistent approach for definingold growth conditions within the Ontario ELCframework. The report also uses the ELC to stratifyand analyze a variety of quantitative data in order toestimate the age-of-onset and duration for old growthconditions across a wide variety of landscapes. Usingan ELC-based approach has made it possible toprovide a better ecological context for old growthforest definitions.

The use of the ELC framework sets the stage forapplying the revised old growth forest types and ELCspatial scales descriptions and age estimates to variousscales of spatial forest inventory. It is now possible toassess the occurrence, distribution and abundance ofold growth across the forested landscapes of Ontarioand incorporate the results into resource managementplanning processes.

Specific assessments are now beginning to fullydescribe the associated structural characteristics of oldgrowth. Studies have begun to quantify trends instanding and downed woody material by ecosite andage. The revised ecosite-based approach will greatlyassist in the design and delivery of this additionalwork.

To date, ELC plot data summarizing trends in plantspecies presence and absence, diversity, and structurehave only been used descriptively in the ecosite andvegetation-type descriptions contained in theecosystem classification products. A quantitativeanalysis of time-related changes in structure at theecosystem level is feasible and needs to be pursued.

Consistent identification of old growth conditions isonly a first step. These initial definitions have beendeveloped in such a way that they can be directlylinked to current forest inventory and mappingdatabases. Through the use of the ecosite definitions(or species and forest units), forest resource maps cannow be consistently assessed for the presence of oldgrowth stand conditions. Currently, work is underwayusing such data for large (200 x 200 km) ecoregionaland planning directions (Figure 5). This detailed forestecosystem inventory can be reclassified to show old

growth conditions (Figure 6 – inside foldout at back of

this report). With these tools, it will be possible to

examine and display the effects of fire regimes,

examine forest management planning approaches,

and assess the results of conservation strategies based

on forest landscape distribution, abundance and

pattern. Work has already begun to apply the old

growth definitions in a variety of spatial ecological

and management planning models.

Currently, non-spatial data are used to draft objectives

for forest management planning. The Strategic Forest

Management Model (SFMM) (Davis 1996c) is then

used to project possible future forest conditions using

simple successional rules. Impacts of predicted

changes in forest inventory can then be examined.

Currently, age class constraints are used as a coarse

filter to ensure the continued presence of old growth

conditions in forest ecosystems. The definitions

presented here will provide a better level of resolution

and more reliable information for planning teams to

use when developing objectives and targets for

conserving old growth and its unique values.

Summary and Next S teps

ONTARIO

U.S.A

ONTARIO

U.S.A Lake Superior

Study Area

CrossroutesForest

Figure 5Location of northwestern Ontario old growth spatial inventory case study.The Crossroute Forest, highlighted in Figure 5, is shown in more detail inFigure 6 (inside foldout at back of this report).

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Summary and Next S teps

The authors anticipate that this definition report willbe used to supplement various operational-level policydirections contained in manuals in regulation underthe Crown Forest Sustainability Act (i.e., the ForestManagement Planning Manual for Ontario’s CrownForests, the Forest Operations and Silviculture Manual,and the Forest Information Manual). Some of theserevisions are now underway. An improved understandingof old growth conditions in Ontario’s forest landscapeswill also permit an assessment of current and proposedmanagement practices intended to perpetuate oldgrowth physical features and characteristics.

This report attempts to provide a mechanism for thereliable identification of old growth conditionsconsistent with current forest inventory and remotesensing information. The approach presented adoptsan ecosystem basis for defining old growth conditions.However, to ensure the definitions can be used incurrent inventory and management practices, they arealso provided for both tree species (Tables 1-4) andoperational forest units (Appendix C).

Numerous questions remain concerning the complexinteractions of disturbance and time in determiningthe establishment, abundance and persistence of oldgrowth conditions in forest stands, ecosystems andlandscapes. Recent work indicates that many earlierstudies of forest disturbance regimes fail to addressthese issues (Baker 1989; Johnson et al 1995; Bergeronet al. 2000), and further study is required to developconsistent tools to predict the impact of dynamicprocesses such as fire, insects and climate.

While this report represents significant progress, thereare still recognized shortfalls in the data. Thefollowing are areas that need to be addressed:

• Continued data collection in the very old ageclasses for each ecosite. While the combination ofavailable datasets used identifies some significantchanges in old growth forest structure, the numberof samples is small compared to the more commonyounger-to-mature stand conditions. These datasetsrequire more work to improve analysis of mature-to-advanced forest age classes.

• Supplementary sampling to improve existingdatasets. The current shortage of data for theforests of southern Ontario must be addressed. Inaddition, some databases were not fully utilized due

to specific data shortfalls. For example, portions ofthe available continuous Forest Resources Inventorydatabase are lacking soil or ecosite data. It isrecommended that an effort be made to relocateand upgrade these and any other existing plots toinclude vegetation, soil, site and ecological data.

• Supplementary sampling of uncommon or under-surveyed ecosites. It is recommended that a specialsampling effort be undertaken to supplement datafor those ecosites for which very small samplesexist.

• Proper description of the historical patterns offorest types and distribution in Ontario. Initialstudies such as Jackson et al. (2000) provide anexcellent beginning, but a comprehensive andconsistent provincial treatment is required. Workis now underway to address this issue in Ontario.

• Supplementary sampling of standing snags anddowned woody material. A primary characteristicof old growth, which has been consistently cited, isthe accumulation of snags and downed woodymaterial with increasing age and with standmortality (Staab 1996). These trends are very poorlyunderstood in Ontario, particularly in fire-dominatedBoreal ecosystems. Data available for central andremnant woodlands in southern Ontario indicatesome interesting trends, but the lack of consistentdata elsewhere in the province precludes broaderanalysis and interpretation. It is recommended thatsupplementary sampling be undertaken to collectdata of this type using an ecoregion/ecosite/agestratification.

• Additional studies to examine wildlife speciesassociations and specific plant associations with oldgrowth forest conditions. Work has now begun toexamine the literature for wildlife species associatedwith old growth forests. Possible habitat andpopulation requirements are being incorporatedinto the spatial modelling and managementplanning trials already mentioned.

• Improved understanding of successional regimesand old growth duration. Tasks include compilationsof literature and expert opinion on successionpatterns in an ecosite framework; remeasurementsof currently available Permanent Sample Plotnetworks to capture ecosite-specific long-term

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trends in growth/mortality, age structure and standtransitions; and, if possible, the establishment ofnew plots to specifically address questions ofsuccession. This is one of the most critical shortfallsin our understanding of old growth landscapedynamics.

• Comparative studies of old growth features innatural versus managed forest stands, ecosystemsand landscapes. An ongoing study in two oldgrowth stands in Lanark County (Site Region 5E,Site District 11) is designed to compare the oldgrowth indicators of a control block and anadjacent block in which modified harvesting isproposed (White 1996). Such studies could becarried out on a regional scale, with growth andyield and/or ELC plots used as controls.

The next stage in applying the conclusions of thisreport is to use the definitions within the context oftypical strategic forest management modellingapproaches (Davis 1996c). Coupling the definitionsand the various spatial thematic natural resource data,geographic information systems and modellingapproaches, the authors intend to explore questions oflocation, extent, genetic diversity, abundance andpatterns of old growth occurrence across various forestlandscapes. Criteria from the provincial ForestResource Inventory (e.g. minimum age and stand size)will be used in a manner similar to an approachadopted in Minnesota (Rusterholz 1996). Work hasbegun using two current management planning areasas case-studies. These trials will provide a real-worldverification of the old growth definitions and willexplore the impacts on current planning processes.

Identifying significant examples of primary remnantold growth stands for all ecosites, including white andred pine on the Canadian Shield, is of value fornatural heritage representation of all ecosites withinthe ELC framework of site districts. Additionalevaluation of old growth forest conditions could beachieved using the methodology developed by Keddyand Drummond (1995). This work will proceed as acomponent of the Provincial Natural Heritage GAPAnalysis and planning process.

Also of interest are several unique forested ecosystemssuch as cliffs and barrens that exhibit elements of oldgrowth. Of note are the 1000+-year-old white cedaron the Niagara Escarpment. Stahle (1996) noted in his

tree-ring chronology studies that adverseenvironments often include very old trees. He useddry-site hardwoods and nutrient-poor swamps asexamples. Predictive models will be required to mapterrain with high potential for such ancient trees.

The information in this report will help naturalresource planners and managers incorporate specificold growth conservation strategies into customaryplanning approaches. It will also facilitate anassessment of the impact of various conservationstrategies on the long-term supply and dynamics ofold growth. Future products associated with the reportwill include new program directions, policies andamendments to guidelines for teams to use inplanning land use and natural resource management.Societal questions about the amount or sufficiency ofold growth in the landscape are not addressed in thisreport.

A second phase of investigation is also underway. Itwill use explicit spatial and theoretical models toexamine conservation biology principles and willinclude predictions of age-class structure based onhistoric disturbance regimes, current inventory andsuccessional projections. A number of researchers haveprovided estimates of natural pre-settlementdisturbance regimes in northern ecosystems (Frissell1973, Henry and Swan 1974, Cwynar 1977,Heinselman 1981, Canham and Loucks 1984,Whitney 1986, Day and Carter 1990a&b, and Frelichand Lorimer 1991). The negative exponential model ofvan Wagner (1978) is one approach that will beexplored to generate “natural” age class structuresbased on such disturbance regimes. Recent studiessuggest a variety of alternatives. Projection of the areaof ecosites and age class structures through time willbe tested using the current Strategic Forest ManagementModel (Davis 1996c) with its built-in successional rulesets, and the Ontario Fire Regime Model (Li et al. 1996;Boychuk et al. 1997). These and other techniques willbe examined in the near future.

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Vora, R. S. 1994. Integrating old-growth forest intomanaged landscapes: A northern Great Lakesperspective. Nat. Areas J. 14(2):113-123.

Ward, P. and A. Tithecott. 1993. The impact of firemanagement on the boreal landscape of Ontario.Ontario Ministry of Natural Resources, Aviationand Fire Management Branch Publication No.305., Queen’s Printer for Ontario. 12 pp.

White, D.J. 1996. Survey and evaluation of the standstructure and life science resources of old growthforest at Billa Lake and Raycroft Lake. EasternOnt. Model For., Kemptville, ON., Ont. Min. Nat.Resour., Carleton Place, ON.

White, M and D. Mladenoff. Old-growth forestlandscape transitions from pre-Europeansettlement to present. Landscape Ecology 9:191-205.

Whitney, G.G. 1986. Relation of Michigan’s pre-settlement pine forests to substrate anddisturbance history. Ecology 67:1548-1559.

Woods, M.E. and A.F. Beckwith. 1987. Storability ofblack spruce in the Clay Belt. Ont. Min. Nat.Resourc., Toronto, ON.; Mensuration Unit, For.Mgt. Br., 15 pp.

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Appendix A: Old Growth MatrixForest Units in Ecoregions 2W, 3W, 4W, 3S, 4S, and 5S (Boreal-West Forest)

General Species Forest Unit Age-of-Onset Average Old Growth Associations Old Growth Stand Duration

Characteristics (yrs) (yrs)

White pine Pw (Dominant) Pw – 150 Pw – 150

Red pine Pr (Dominant) Pr – 130 Pr – 110

White cedar, Larch OC Ce – 140 Ce – 210+La – 100 La – insf. data

Black spruce Sb (Low) Sb – 160 Sb – 190+

Black spruce Sb (Deep) Sb – 120 Sb – 30 to 80

Black spruce Sb (Shallow) Sb – 130 Sb – 40 to 60

Jack pine Pj (Pure) Pj – 100 Pj – 30 to 80

Trembling aspen Po (Pure) Po – 100 Po – 20 to 70

White birch Bw (Dominant) Bw – 110 Bw – 20 to 30

Black ash, Balsam poplar OH Ab – 100 Ab – 20 to 50Pb – 90 Pb – 40 to 70

Black spruce, Jack pine Con Mix 1 Sb – 110 Sb – 20 to 60Pj – 100 Pj – 30 to 70

Balsam fir Bf (Dominant) Bf – 80 Bf – 40 to 70

Black spruce, White spruce mix Sb (Mix) Sb – 110 Sb – 30 to 80Sw – 120 Sw – 50 to 70

Trembling aspen HWD (Dominant) Po – 100 Po – 10 to 20

Trembling aspen, White birch Hardwood (Mix) Po – 100 Po – 20 to 50Bw – 110 Bw – 20 to 40

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Appendix A: OLD GROWTH MATRIXForest Units in Ecoregions 3E (Boreal-East Forest)

Please note: Forest units represent aggregations of forest stand conditions for the purposes of strategic and tactical forest planning.

As such, they provide a more generalized representation of the forest than do the ecosystem classes of the ELC. The forest units are

currently legislated classes for use in forest management planning, and the following tables provide a tool for incorporating the

revised old growth age-of-onset and duration estimates into current planning processes.

General Species Forest Unit Age-of-Onset Average Old Growth Associations Old Growth Stand Duration

Characteristics (yrs) (yrs)

White pine, Red pine Pw/Pr Pw – 130 Pw – 170Pr – 130 Pr – 110

Balsam poplar, Black ash, LH1 Pb – 80 Pb – 10 to 30Hard maple, Soft maple, Ab – 100 Ab – 20 to 50

Yellow birch TH1 Mh – 140 Mh – 500+Ms – 80 Ms – 40 to 80By – 150 By – 500+

Black spruce Bog Sb – 150 Sb – 200+

Black spruce Sb1 Sb – 120 Sb – 30 to 80

Jack pine Pj1 Pj – 110 Pj – 20 to 60

White cedar, Larch and Black spruce LC1 Ce – 140 Ce – 210+La – 100 La – insuf. dataSb – 120 Sb – 230+

Jack pine Pj2 Pj – 100 Pj – 20 to 50

Black spruce, Jack pine Sp1 Sb – 110 Sb – 20 to 70Pj – 90 Pj – 30 to 50

Balsam fir, White spruce, Black spruce SF1 Bf – 70 Bf – 40 to 70Sw – 110 Sw – 20 to 110Sb – 110 Sb – 20 to 30

Trembling aspen Po1 Po – 90 Po – 20 to 50

White birch Bw1 Bw – 90 Bw – 20 to 40

Jack pine, Trembling aspen, MW1 Pj – 100 Pj – 20 to 40White Birch Po – 90 Po – 30 to 40

Bw – 90 Bw – 10 to 20

Trembling aspen, Black spruce, MW2 Po – 100 Po – 20 to 40White birch Sb – 110 Sb – 20 to 50

Bw – 100 Bw – 40 to 50

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Appendix BDatabase Descriptions

Boreal Forest Databases

The first stage of analysis was to uncover, clean,compile and analyze potential datasetscontaining information on undisturbed natural

stands. Minimum data requirements for each plotwere (1) stand-level mensuration data (tree height,diameter at breast height (DBH), density and age, byspecies), and (2) associated soil and vegetationcharacteristics.

The following is a list of the datasets and the numberof plots meeting these criteria. They comprise the finalold growth database. Not all plots within a dataset metthe minimum criteria. For example, some plots weremissing tree heights, others had no soil and/orvegetation data, and some had errors in themensurational tally that could not be corrected oraccounted for. Plots with these shortcomings weredeleted from the database. The total number of plotsfor Boreal Ontario was 2312.

Deschamps Poplar Growth Study Plot data were collected as points in time. Plot sizeswere varied to capture a minimum number of trees.Representative stem analysis trees were taken fromoutside the plot. Within each plot, diameter wasmeasured on all trees, but height was only measuredon selected species (Populus tremuloides and P.

balsamifera). These trees were most likely the treesremoved for stem analysis outside the plot. Selectedstem analysis trees reflected plot DBH distribution. Siteinformation consisted of moisture and drainageregimes, and Forest Ecosystem Classification vegetationand soil types. Ages were available, but no detailed soilprofile data were recorded.

Forest Ecosystem Classification, Boreal-Eastand Boreal-West (Sims et al. 1996; McCarthyet al. 1994)Plot data were collected as points in time. Extensiveplots in the former MNR North Central Region and allNorthwestern Region plots consisted of pointsampling using a wedge prism. All “in” trees weremeasured for DBH and only representative trees weremeasured for height and age. Intensive plots in theNorth Central Region were a fixed area (10 m x 10 m)in which all trees were measured for both DBH andheight while only selected trees were measured for age.Detailed soil, site and location data were also available.

Growth and Yield, Boreal-East and Boreal-WestData from the Provincial Growth and Yield datasetrepresent only points in time, since only initial plotestablishment data were used (very few plots hadremeasurement data available). Within a mortalityplot, all three growth plots were amalgamated toobtain a stand value. Each growth plot was a fixedarea (11.28 m radius). All trees within the plots weremeasured for DBH. Heights and ages were assessed forselected representative trees. Detailed soil, site andlocation data were also available.

Kimberly-Clark Permanent Sample PlotsPlot data consisted of differing numbers ofremeasurements at approximately five-year intervals.Most plots were a fixed area (0.08 ha). All trees withina plot were measured for DBH. Selected representativetrees had heights and ages taken. Some detailed soilprofile data were available, with parent material noted.This permanent sample plot network was establishedby Kimberly-Clark (KC) with the majority ofremeasurements conducted by KC personnel. At thattime, tagged trees were measured, but in-growth wasnot measured. However, when MNR took over the

Source Dominant Boreal-West Boreal-EastSpecies Region Region

Deschamps Po 32

Forest Ecosystem Classification All 661 708

Growth and Yield All 97 61

Trout Forest Sb 72

Morawski All except Pw, Pr 231 122

Kimberly-Clark Pj, Sb 114

Spruce Falls Pulp and Power Sb 99

Carleton and Arnup Pw, Pr 60

Storability Po 55

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permanent sample plot network in 1981, subsequent

remeasurements included tagged and non-tagged

trees.

Poplar Storability DatasetPlot data were collected as points in time. Each plot

was a fixed area (10 m x 10 m), similar to Forest

Classification Ecosystem plots. Representative stem

analysis trees were removed outside the plot. Heights

were measured either on selected trees within plots, or

on most likely representative stem analysis trees

outside the plot. All trees within the plots were

measured for DBH. Site information consisted of

moisture regime and drainage, Forest Ecosystem

Classification vegetation and soil types, and age.

Detailed soil profile information was available.

Spruce Falls DatasetPlot data consisted of differing numbers of

remeasurements or trends through time. Each plot was

a fixed area. The plots varied in size; the varying sizes

were adjusted for more analysis. All trees within the

plots were measured as the number of stems and

average height per DBH class per species.

Measurement intervals varied between 5 and 10 or

more years. Site information consisted of parent

material; no detailed soil profile data were available.

Trout Forest DatasetPlot data consisted of a series of prism point samples.

All trees were tallied and measured for DBH; however,

only black spruce was measured for heights and ages.

Site information consisted of moisture and drainage

regime, parent material and a somewhat detailed soil

profile.

Survey of Pathological Condition in theForests of Ontario (Morawski et al. 1958)Plot data were collected throughout central and

northern Ontario for a variety of important forest

species. A total of 800 20m x 20m plots were sampled

for stand composition, heights, ages, density and

pathological condition. Soil, site, topography and

understory conditions were also tallied and used for

accurate ecosite identification.

Great Lakes-St. Lawrence Forest Databases A total of 2696 plots were used in the Great Lakes-St.Lawrence old growth analysis, from the followingsources:

Source Dominant Species No. of Plots

Forest Ecosystem Classification All 1536

Growth and Yield All 725

Morawski Mh, By, He 435

Forest Ecosystem Classification (Chamberset al. 1997) Plot data were collected as points in time. Thedatabase contains species and DBH for all trees andage at breast height for a sub-sample of trees on eachplot. All plots were classified to the appropriate ecositeusing vegetation and soil data collected at each site.

Growth and YieldData from growth and yield permanent sample plotscurrently represent only the first measurement. Alltrees within the plot were measured for DBH, andselected trees were measured for heights and ages.Detailed soil, site and vegetation data allowed forallocation of a plot to the appropriate ecosite.

Carleton and Arnup Red and White PineReport (Carleton and Arnup 1993)Plots were established as points in time and were fixedat 20 m x 20 m. Within each plot all trees weremeasured for DBH and height. Age was determinedfor a sub-sample. Adjacent to each plot and sharing aplot edge, a second 20 m x 20 m plot was located.Within the second plot, each tree was measured forDBH only. For analysis purposes, each pair of plotswas analyzed as one composite observation. Detailedsoil, site and location data were also available.

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Appendix CAnalysis Methodology

Analysis Methodology for Boreal ForestDatabases

The approach to analyzing Boreal Forest regiondatabases has been to describe quantitatively, atthe stand level, old growth age-of-onset and

duration periods for Ontario’s major tree species orforest community associations, with particular referenceto application for forest management planning.

Age-of-onsetThe age-of-onset for old growth conditions is definedas the age at which a species has attained at least 75per cent of its maximum potential diameter (for anecosite or forest unit) and makes up more than 50 percent of the stand basal area.

In addition, height growth trends over time for eachspecies by ecosite and forest unit were analyzed. Theage at which the average stand height incrementstarted to decline was used as an indicator of oldgrowth age-of-onset. Then the results were comparedto the age at which a high percentage of cull appearedin the species of interest, as determined from anexamination of Morawski’s cull survey data.

DurationFor forest management purposes, it is important toknow how long stands remain in an old growthcondition. Interpretations for wildlife habitat, harvestscheduling, growth and yield, and vegetation successionrequire an estimate of the longevity of stands.

The duration of old growth conditions was firstcalculated as the difference between the age-of-onsetand the age at which the dominant species ceases tooccupy at least 30 per cent of the stand basal area. Atthis advanced age, the stand would no longer bedominated by the species of interest, although itwould still be present.

Ecosite Ecosite (ES) information was either available, or wasdetermined by using site and vegetation data and thenusing the appropriate regional ecosite key. In plotnetworks where there were multiple remeasurements(i.e., Kimberly Clark and Spruce Falls), ecosite

designations were based solely on the initial or firstmeasurement. For analysis purposes, a unique ecositequalifier was needed to distinguish ecosites in theBoreal-East region from those in the Boreal-West.Therefore the variable ECO was created with valuestagged with either an “e” or a “w” to indicate theregional location of each plot. For low sample sizes,associated ecosites were grouped, and these groupswere identified with the variable ECOSITE. Thefollowing is the final list of Boreal Forest regionecosites or ecosite groupings for old growth analysis.

Mensuration DataThe following values were calculated and carriedthrough to the old growth summary table:

STEMSHA – Density on a per hectare basis for eachunique tree species on the plot.

QUDBH – Quadratic mean diameter taken at breastheight (1.3 m) for each unique tree species on the plot.Quadratic mean diameter gives an indication ofdiameter weighted by density.

BAHA – Basal area in m2 per hectare for each uniquetree species.

VTCMHA – Total volume in m3 on a per hectare basisfor each unique tree species was determined using aform factor methodology. A form factor method was

BOREAL ECOSITEEast

east 10east 11east 12east 13p/reast 14east 15,16 & 17east 1p/reast 2east 3east 4east 5m/feast 6ceast 6m/feast 7ceast 7m/feast 8east 9peast 9reast 18,19, 20,21east 15, 16,17

West

west 11,15west 12west 13west 14west 16west 17west 18,24west 19west 20west 21west 22west 23west 25west 26west 27west 28west 29,30west 31west 32,33west 34,35west 36west 37west 38

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used for plots where height was not measured for alltrees on each plot. Where both DBH and height weremeasured, total volume was calculated using metricconversions of Honer’s volume equations (Kavanagh1979). The ratio of basal area and total volume foreach species was determined. This form factor ratiowas then applied to trees not initially measured forheight to calculate the total volume for all trees in theplot. Usually the form factor ratio was calculated byspecies and ecosite over the entire dataset and not forindividual plots.

Where only selected species were measured for height,some of the form factor ratio calculations by speciesand ecosite did not represent all species. In this case, asite class was determined for each plot based onworking group species, height and age. This site classwas then applied to all species and a volumedetermined using a single entry volume table (Maurer1993).

HT – Mean height for a given tree was determineddirectly on most plots. Where heights were notavailable, an estimate of mean height was derivedusing Honers’ equation, namely, the quadratic meandiameter and mean tree total volume (calculated bydividing total volume by the number of stems).

Canopy Species v. Non-canopy SpeciesCanopy position provided an indication of a plot’scomposition if viewed from above or on aerial photos,in order to more closely represent species compositionin the Forest Resources Inventory. Canopy positionwas determined using all the trees measured for heightin the Boreal-West growth and yield dataset, as allthose trees were given a canopy position (emergent,dominant, co-dominant, intermediate, suppressed,understory and open understory). By calculating theratio of suppressed and understory tree heights todominant, co-dominant and intermediate tree heightsfor each plot, the authors were able to determine thepercentage (72.9 per cent) of top height at which atree became suppressed. Applying this number to eachplot’s mean top height (MTHt) variable, it was thenpossible to create a variable called ABOVE, where thevalue indicates if the species is overstory (0) orunderstory (1). Only overstory species were used inthe old growth analysis.

Mean Top Height Mean top height (MTHt) for each plot in the databasewas determined to separate understory species fromcanopy species. A database drill sort was used asfollows:

Step 1: Pure standFor all single species or pure species plots, mean heightfor that species was considered the MTHt.

Step 2: Single species dominated standsFor single species dominated stands, MTHt is themean height for the species with the maximum basalarea for the plot that is also the tallest species and hasthe lowest density.

Step 3: Stands with few very large remnant treesFor stands with few large remnants, the tallest specieswith a density of ≤ 26 stems/ha (single tallied species),plots were considered to have potential emergents.Then:

Step 3.1: At least two species in the canopy withno emergentsFor a given plot, if the species of the second tallestheight is ≥ 72.9 per cent of the tallest species height,use step 4 to calculate MTHt.

Step 3.2: Emergent species, with the secondtallest species as the main canopyFor a given plot, if the species of the second tallestheight is ≤ 72.9 per cent of the tallest species AND thesum of the stems/ha for both the tallest and thesecond tallest species is >26 stems/ha, then MTHt isthe mean height of the second tallest species.

Step 3.3: Emergent species, with the secondtallest species as the potential main canopyFor a given plot, if the species of the second tallestheight is ≤ 72.9 per cent of the tallest species AND thesum of the stems/ha for both the tallest and the secondtallest species is <26 stems/ha, look at the plot dataand subjectively choose the species that best representsMTHt. Most likely this is second tallest species.

Step 4: Dual or bi-layer canopiesUse the following weighted MTHt method:((BA per cent of tallest species) � (Height of tallestspecies) + (BA per cent of the second tallest species) �(Height of the second tallest species)) � (BA per centof tallest species + BA per cent of the second tallestspecies).

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Plot Age Plot age was determined to give an indication of theage since stand initiation or time since last majordisturbance. No attempt was made to determine theage of individual species within each plot. Age wasdetermined by looking at the maximum andminimum age samples for each plot. If the differencewas 20 years or less, the plot was considered even-aged, and maximum age represented time sinceinitiation. If the difference between maximum andminimum age was greater than 20 years, plot datawere examined to determine which sampled agewould more accurately represent age. This was donebased on looking at:

• species compositions and associations; and

• potential emergent or veteran trees (based on ageonly).

Once each plot was assigned an age, an additional ageclass was assigned based on ten-year age classes (i.e., 0to 10 = 5, 11 to 20 = 15, etc.). AGE is the total age orinitiation age and AGE10 is the age class.

Working Group and Site Class Each plot was assigned two working group variables andtwo site class variables. Each pair of variables representsthe working group and site class, either for all speciesregardless of canopy position (both overstory andunderstory), or for just canopy as if being viewed fromabove. WG_A and SC_A represent working group andsite class based on all trees. WG_O and SC_O representworking group and site class based on canopy speciesonly and were used in the analysis. Both working groupvariables represent the species expressing the most basalarea on that plot. Site class was determined based oncomparisons to Plonski (1974).

Benchmark Forest Unit Two benchmark forest units were established for eachplot. The first forest unit (FU_ALL) was determinedusing all trees in the plot regardless of canopyposition. The second (FU_ABOVE) was used in theanalysis and was determined after eliminating thosetrees classified as being in the understory, in order toconform with Forest Resources Inventoryinterpretation. Like the method used for assigningecosites, each plot was assigned a forest unit based onthe definition criteria for its geographic location.Where plots were remeasured over time (i.e., Kimberly

Clark and Spruce Falls), forest unit designations werebased on the initial measurement. Sort rules for forestunit classification are specific to each region and aredescribed on page 43.

Note:• Since Pj Shallow and Po Shallow forest units had

few samples, they were combined with theirrespective deep forest units.

• Ecosites were used where appropriate to improveclassification precision.

Analysis Methodology for Great Lakes-St.Lawrence Forest Databases

Analysis for Species-specific Age-of-onsetFor this analysis, a database composed of 2696 ForestEcosystem Classification, growth and yield andMorawski cull survey plots from the Great Lakes–St.Lawrence Forest region of central Ontario wasassembled. The database contained information onspecies and DBH for every tree, and age at breastheight for a sub-sample of trees per plot (about 40 percent). Age at breast height was translated to true ageby adding a species-specific correction factor. Missingages were estimated in one of the following ways:

1. A tree was assigned the average age of other trees inthe plot that were of similar species and diameterclass (5 cm classes used); or

2. A tree was assigned the average age of other trees inall plots occurring within the same ecosite thatwere of similar species and diameter class; or

3. A tree was assigned the average age of other trees inall plots within the database that were of similarspecies and diameter class.

For each species in each plot, a quadratic meandiameter (QDBH) and a quadratic mean age (Qage)(i.e., age or DBH weighted by basal area) wascalculated. It was hoped this would reduce the effectof suppressed and intermediate trees on estimates ofplot age and DBH and thus more closely matchinformation from the Forest Resources Inventory.

Initially, the approach used in the Boreal-East andBoreal-West regions was attempted. Unfortunately,this yielded extremely low age-of-onset. Two problemswere identified:

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1. Because of the mixed nature of the Great Lakes-St.Lawrence Forest region, when the authors lookedonly at plots where a species represented > 50 percent of the total BA, the sample size was small.

3. Most of the plots reflected mature forest. Forexample, in the case of jack pine on Ecosite 15, themaximum QDBH was 32 cm but all plots had aQDBH that exceeded 16 cm.

As an alternative, polynomial regression models weredeveloped to predict the relationship between Qageand QDBH. For each species, all plots where thespecies comprised ≥ 10 per cent of the plot BA wereused. After some experimentation, the followingmodel was found to generally provide the best fit tothe data:

QDBH = b1*Qage1.5 – b2*Qage3

This function provided a good fit to the data in theolder age classes, but tended to overestimate QDBHin the younger age classes (< 40 yrs).

Stands were considered to have approached oldgrowth status when the predicted QDBH wasapproximately 85 to 90 per cent of the maximumQDBH. These numbers became the preliminaryestimates of the age-of-onset for each major species(species that represented ≥ 10 per cent of the BA on atleast one ecosite) within each ecosite grouping.

Analysis for Ecosite-specific Age-of-onsetThe transition from mature forest to old growthshould be accompanied by a significant change instand structure and/or composition. Specifically, it wasassumed that the transition to old growth would besignalled by a decline in stand height, mean DBH andnet merchantable volume (reflecting changes instocking and cull), and a significant shift in overstoryspecies composition. Estimates of the age-of-onset ofold growth conditions were derived based on the age-related pattern for each of these variables.

Age-of-onset Based on Height Growth Forest Resources Inventory data were assembled forthe entire Great Lakes-St. Lawrence Forest region(Algoma, Northshore, Vermillion, Temagami,Nipissing, French-Severn, Algonquin Park, Pembroke,Bancroft-Minden and Lanark-Mazinaw managementunits). An ecosite type was assigned to each polygonusing a conversion algorithm contained in the Ontario

Wildlife Habitat Analysis Models toolkit. Theheight/age relationship for each ecosite was modelledusing polynomial regression (a number of 3- and 4-term models were developed). Age-of-onset for eachecosite was defined as the point where the currentannual height increment reached zero (i.e., heightpeaked).

Age-of-onset Based on DBH GrowthFor each ecosite, the relationship between plot QDBHand Qage from the central Ontario Forest EcosystemClassification dataset was modelled using polynomialregression. Age-of-onset was defined for each ecosite asthe point where the current annual DBH incrementreached zero (i.e., DBH peaked).

Age-of-onset Based on Volume GrowthNet merchantable volume was calculated for eachpolygon in the Forest Resources Inventory dataset ofthe Great Lakes-St. Lawrence Forest region based onvolume equations developed by Murray Woods andMargaret Penner, modified by Basham’s cull factors.The volume/age relationship was modelled for eachecosite using polynomial regression. Age-of-onset foreach ecosite was defined as the point where thecurrent annual volume increment reached zero (i.e.,volume peaked).

Age-of-onset Based on Significant Shift inSpecies CompositionMean species composition was calculated for eachecosite by 10-year age classes based on the ForestResources Inventory dataset of the Great Lakes-St.Lawrence Forest region. For each ecosite, a hierarchicalcluster analysis (average linkage, Euclidean squareddistance) was conducted. Age-related clusters wereidentified and age-of-onset was defined as the agecorresponding to the oldest age-related cluster.

Species- and Ecosite-specific Ages-of-onsetPreliminary estimates of ecosite-specific ages-of-onsetwere based on the average of the values derived fromthe height, DBH, volume and species shift analyses. Toensure consistency between the species and ecosite-specific estimates, ages-of-onset were adjusted slightlyso the ecosite-specific age-of-onset was similar to thatderived by calculating a weighted mean for theecosite, based on the species-specific age-of-onset forthe appropriate ecosite group.

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Species-specific Duration PeriodA slightly modified version of the approach used inthe Boreal-East and Boreal-West Forest regions toestimate duration of old growth was attempted. Themean Qage of plots (DurQage) where Qage > age-of-onset and species BA ≥ 10% of plot BA was calculated.Unfortunately, the difference between DurQage andage-of-onset was very small for many species (e.g., onecosites 11 to 14, mean age-of-onset for jack pine was90 but DurQage was only 105). Thus, the lower end ofthe duration period was defined as DurQage plus 1standard deviation. The upper end of the durationperiod was defined as DurQage + 3 standard deviationsor the Qage of the oldest plot.

For some species there were insufficient data todevelop a reasonable estimate of duration. Thesespecies are noted in Table 3 as having “Insuf. data.”For some species the duration is listed as > 500 yrs.These species are generally capable of self-perpetuationthrough single tree or multi-tree gap phasereplacement processes.

Ecosite-specific duration periods are based on a weightedaverage of the species-specific duration periods.

Analysis Methodology for Deciduous ForestDatabases (Site Regions 6E and 7E)The development of old growth estimates for theDeciduous Forest region (ecoregions 6E and 7E)ecosites was based on an examination of availabledatasets from the ELC (Lee et al. 1998) and Growthand Yield programs in this region. A recent survey ofheritage woodlands of southern Ontario (Larson et al.1999), a compendium of data from old growth standsin the eastern United States (Tyrell et al. 1998) andother relevant literature were reviewed.

The lack of old growth conditions in forest stands insouthern Ontario, as discussed previously and asevidenced by the querying of available survey datafrom the above sources, made it impractical to pursueany kind of quantitative analysis. The ELC frameworkis used, however, to summarize estimates for species-specific minimum age for old growth, and lifeexpectancy. In some cases, minimum ages from thecentral Ontario matrix are used. Overall, minoradjustments have been made from the 1994 version ofthe Old Growth Forests Policy Advisory Committeetable for this region (MNR 1994, pp. 74-76).

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A p p e n d i x C

Boreal East Benchmark Forest Units and Decision Rules

Forest Unit Description Sort Rule

Pw/Pr White and red pine Pw+Pr >=0.4

LH1 Lowland hardwoods Lh >=0.3

TH1 Tolerant hardwoods Lh+Mh+Uh >=0.3

Bog Black spruce bog Sb+La >=0.7 AND Pw =0 AND Site Class =4 OR ecosite = 14

Sb1 Black spruce lowland Sb >=0.8 AND Mh+Uh+Pr =0 AND Pw+Pj <=0.1

Pj1 Jack pine Pj >=0.7 AND Po+Bw+Mh+Uh+Lh <=0.2

LC1 Lowland conifer Ce+La+Sb >=0.8 AND Mh+Uh+Pr =0 AND Pw+Pj <=0.1

Pj2 Jack pine mixedwood Pj+Sb+Pr >=0.7 OR Pj >=0.5 AND Pj+Sb+Bf+Sw+He+Pw+Pr+Ce+La

>=0.7 AND Bf+Sw+He+Pw+Ce+La <=0.2 AND Pj >=Sb

Sp1 Spruce / Pine Sb+Sw+Bf+Ce+La+Pw+Pj+Pr+He >=0.7 AND Bf+Ce+Pw+La+Sw+He <=0.2

OR Pj >=0.3

SF1 Spruce / Pine / Fir Sb+Sw+Bf+Ce+La+Pw+Pj+Pr+He >=0.7

Po1 Poplar Po+Bw+Mh+Uh+Lh >=0.7 AND Po >=0.5 AND Po >=Bw

Bw1 White birch mixedwood Po+Bw+Mh+Uh+Lh >=0.7

MW1 Mixedwood 1 Pj+Pr >=0.2

MW2 Mixedwood 2 else

Boreal West Benchmark Forest Units and Decision Rules

Forest Unit Description Sort Rule

Pw Dom White pine dominant Pw+Pr >=0.4 AND Pw >Pr

Pr Dom Red pine dominant Pw+Pr >=0.4 AND Pr >Pw

OC Other conifer Ce+La >=0.5 OR (WG = Ce OR La AND Pr+Pw+Pj+Sw+Bw <=0.1)

SbLow Black spruce lowland (Sb+Ce+La >=1 AND Site Class =3 OR 4) OR (Sb+Ce+La =1

AND Ce+La >=0.1 AND SC =0, 1, or 2

AND ecosite = 34, 35, 36 or 37)

SbDeep Black spruce deep soil Sb >=0.7 AND Po+Bw <=0.2 AND NOT ecosite 11 or 12

SbSha Black spruce shallow soil Sb >=0.7 AND Po+Bw <=0.2

PjDeep Jack pine deep soil Pj >=0.7 AND Po+Bw<=0.2 AND NOT ecosite 11 or 12

PjSha Jack pine shallow soil Pj >=0.7 AND Po+Bw<=0.2

PoDeep Poplar deep soil Po >=0.7 AND NOT ecosite 11 or 12

PoSha Poplar shallow soil Po >=0.7

BwDom White birch dominant Bw>=0.6 AND Po+Bw >=0.7

OH Other hardwood Lh+Uh+Mh >=0.3

ConMix1 Conifer dominated mixedwood Sb+Sw+Pj+Pr+Bf >=0.7 AND Bf <=0.1 AND Po+Bw <=0.2

AND WG= Sw, Sb or Pj

BfDom Balsam fir mixedwood Bf >=0.4 AND Bf+Sb+Sw+Pj >=0.5

SbMix Spruce mixedwood (Sb+Sw+Pj+Pw+Pr+Bf+Ce+La >=0.5 AND WG = Pw, Pr, Sb, Sw, Pj, Bf)

OR (Sb+Sw+Pj+Pw+Pr+Bf+Ce+La >=0.51 AND NOT WG =

Pw,Pr,Sb,Sw,Pj,Bf)

HwdDom Hardwood Po+Bw+Lh+Uh+Mh >=0.7

HwdMix Hardwood mixedwood Po+Bw+Lh+Uh+Mh >=0.49

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51476(1.0 k P.R., 12 05 03)ISBN 0-7794-4603-8

Printed on recycled paper.

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Documents

Old Growth Forest Definitions for Ontario · Old Growth Forest Definitions fortOntario / 1 Executive Summary T his Old Growth Forest Definitions for Ontario report provides working