a field guide to ecosystem identiﬁ cation for the …a field guide to ecosystem identiﬁcation...

A Field Guide to Ecosystem Identifi cation for the Boreal White and Black Spruce Zone of British Columbia

The Best Place on Earth

Ministry of Forests and Range

Forest Science Program

LAND MANAGEMENT HANDBOOK

65

2011

A Field Guide to Ecosystem Identification for the Boreal White and Black Spruce Zone of British Columbia

S. Craig DeLong Allen Banner William H. MacKenzie Bruce J. RogersBenita Kaytor

The Best Place on Earth

Ministry of Forests and Range

Forest Science Program

ii

Library and Archives Canada Cataloguing in Publication

A field guide to ecosystem identification for the boreal white and black spruce zone of British Columbia /C. DeLong ... [et al.].

Includes bibliographical references. ISBN 978-0-7726-6268-2

. Ecological zones--British Columbia, Northern. 2. Ecological regions-- British Columbia, Northern. 3. Biotic communities--British Columbia, North-ern. I. DeLong, S. C. (Craig) II. British Columbia. Ministry of Forests and Range

SD397 S77 F55 20 577.097 C200-90742-0

Citation

DeLong, C., A. Banner, W. H. MacKenzie, B. J. Rogers, and B. Kaytor. 20. A field guide to ecosystem identification for the Boreal White and Black Spruce Zone of British Columbia. B.C. Min. For. Range, For. Sci. Prog., Victoria, B.C. Land Manag. Handb. No. 65. www.for.gov.bc.ca/hfd/pubs/Docs/Lmh/Lmh65.htm

Prepared forB.C. Ministry of Forests and RangeResearch Branch, Victoria, B.C.

Copies of this report can be obtained from:Crown Publications, Queen’s Printer PO Box 9452 Stn Prov Govt, 563 Superior Street, 2nd Floor, Victoria, BC V8W 9V7 800 663-605 www.crownpub.bc.ca

For more information on Forest Science Program publications, visit: www.for.gov.bc.ca/scripts/hfd/pubs/hfdcatalog/index.asp

© 20 Province of British ColumbiaWhen using information from this or any Forest Science Program report, please cite fully and correctly.

The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the Government of British Columbia of any product or service to the exclusion of any others that may also be suitable. Contents of this report are presented as information only. Funding assistance does not imply endorsement of any statements or information contained herein by the Government of British Columbia. Uniform Resource Locators (URLs), addresses, and contact information contained in this document are current at the time of printing unless otherwise noted.

ACKNOWLEDGEMENTS

The classification and interpretations presented in this field guide have evolved over the past 30 years through the collective work of several individuals involved in the many phases of the provincial ecological classification project.

Preliminary ecological classifications, description, and interpretation of units, and biogeoclimatic boundary refinement were developed in part by R. Annas, L. Jang, A. MacKinnon, D. Meidinger, J. Pojar, and E. Wright. In addition to these individuals, many others collected field data that form the basis of the classification presented in this guide. J. Pojar, G. Argus, F. Boas, T. Goward, and W. Noble identified difficult vascular plant, bryophyte, and lichen specimens.

The format and content of this guide have benefited from guides from other forest regions in British Columbia and some of the aids to site and soil description have been adapted from these guides. V. Foord contrib-uted to the Climate Section of the guide.

Review comments were provided by R. Kabzems, D. MacKillop, and D. Meidinger. Thanks to P. Nystedt and R. Scharf for co-ordinating layout, graphics, and publication.

Plant illustrations are reprinted by permission of the University of Washington Press, Flora of the Pacific Northwest (Hitchcock and Cron-quist 973); of W. Schofield, for P. Drukker-Brammall’s moss illustra-tions from Some Common Mosses of British Columbia (Schofield 992); and of T. Goward for use of lichen illustrations from The Lichens of Brit-ish Columbia (Goward 999). The British Columbia Ministry of Forests and Range Northern Interior Region provided funds for preparation and publication of this guide.

iii

CONTENTS

Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. Objectives/Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Regulatory and Standards Context . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Other Sources of Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 Guide Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 Training Courses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Biogeoclimatic Ecosystem Classification (BEC) System . . . . . . . . . . . 52. An Overview of the BEC Classification System . . . . . . . . . . . . . . . . . 52.2 Zonal (Climatic) Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.3 Site Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.4 Unit Numbering Convention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3 The BWBS Zone in British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Disturbance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43.3 Physiography and Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.4 Climate of the Boreal Forest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4 Overview of Biogeoclimatic Units of the BWBS Zone . . . . . . . . . . . . . 324. BWBSdk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.2 BWBSmk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364.3 BWBSmw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374.4 Murray BWBSwk (BWBSwk) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384.5 Graham BWBSwk (BWBSwk2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384.6 Kledo BWBSwk (BWBSwk3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.7 BWBSvk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5 How To Identify an Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405. Field Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405.2 Layout of Biogeoclimatic (BGC) Unit Sections . . . . . . . . . . . . . . . . . . 62

6 Ecosystem Units of the BWBS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 6. Dry Cool Boreal White and Black Spruce (BWBSdk) . . . . . . . . . . 67

BWBSdk/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75BWBSdk/02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76BWBSdk/03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77BWBSdk/04 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78BWBSdk/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

v

vi

BWBSdk/ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80BWBSdk/06B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86BWBSdk/026B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87BWBSdk/036B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88BWBSdk/06B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89BWBSdk/2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

6.2 Moist Cool Boreal White and Black Spruce (BWBSmk) . . . . . . . 9BWBSmk/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99BWBSmk/02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00BWBSmk/03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0BWBSmk/04 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 02BWBSmk/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 03BWBSmk/ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 04BWBSmk/06B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0BWBSmk/06B.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BWBSmk/026B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2BWBSmk/036B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3BWBSmk/046B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4BWBSmk/06B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5BWBSmk/2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6.3 Moist Warm Boreal White and Black Spruce (BWBSmw) . . . . . . 7BWBSmw/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25BWBSmw/02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26BWBSmw/03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27BWBSmw/04 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28BWBSmw/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29BWBSmw/ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30BWBSmw/06B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36BWBSmw/026B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37BWBSmw/036B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38BWBSmw/046B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39BWBSmw/06B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40BWBSmw/6B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4BWBSmw/6B.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42BWBSmw/2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

6.4 Murray Wet Cool Boreal White and Black Spruce (BWBSwk) . 45BWBSwk/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53BWBSwk/02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54BWBSwk/03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

BWBSwk/04 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56BWBSwk/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57BWBSwk/ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58BWBSwk/06B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64BWBSwk/026B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65BWBSwk/036B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66BWBSwk/046B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67BWBSwk/06B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68BWBSwk/06B.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

6.5 Graham Wet Cool Boreal White and Black Spruce (BWBSwk2) 7BWBSwk2/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79BWBSwk2/02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80BWBSwk2/03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8BWBSwk2/04 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82BWBSwk2/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83BWBSwk2/ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84BWBSwk2/06B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90BWBSwk2/026B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9BWBSwk2/036B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92BWBSwk2/046B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93BWBSwk2/06B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94BWBSwk2/6B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

6.6 Kledo Wet Cool Boreal White and Black Spruce (BWBSwk3) . . 97BWBSwk3/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204BWBSwk3/02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205BWBSwk3/03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206BWBSwk3/0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207BWBSwk3/ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

7 Wetlands and Non-forested Ecosystems of the BWBS Zone . . . . . . . . 2097. Site Classes in the BWBS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2097.2 Common Wetland and Non-forested Site Associations of

the BWBS Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288 Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

APPENDIX Table for conversion of old biogeoclimatic unit and site unit numbers

and names to new BGC unit and site unit nubers and names . . . . . . . . . 244

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viii

tables2. System of naming and coding interior biogeoclimatic units . . . . . . . . . . 73. Environmental characteristics of the BWBS zone and adjacent

zones in northern British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.2 Comparison of climate variables for the BWBS zone and adjacent

portions of zones in northern British Columbia . . . . . . . . . . . . . . . . . . . . 263.3 BWBS 97–2000 climate normals: Environment Canada weather

stations with World Meteorological Organization Standards . . . . . . . . . 283.4 Summary of climate data for biogeoclimatic units within the

BWBS zone of northern British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . 294. Environmental characteristics of biogeoclimatic units within the

BWBS zone of northern British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . 335. General steps for site location and description . . . . . . . . . . . . . . . . . . . . . 435.2 Section and page numbers for biogeoclimatic unit sections . . . . . . . . . 485.3 Site and soil factors to be collected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495.4 Identification of upland humus forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55.5 Hand texturing guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525.6 Properties of soil separates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525.7 Choice of procedures for mature and climax stands versus recently

disturbed/early seral sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565.8 Definitions of terms used in the keys to identification of relative

soil moisture and nutrient regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575.9 Table for estimation of soil nutrient regime . . . . . . . . . . . . . . . . . . . . . . . 65.0 Rules for identifying species values in the Characteristic Vegetation

section of the site/seral unit summary page . . . . . . . . . . . . . . . . . . . . . . . . 667. Distribution and abundance of wetland, riparian, grassland, and

other non-forested site classes in subzones of the BWBS . . . . . . . . . . . . 27.2 Wetland Site Associations occurrence by BGC unit . . . . . . . . . . . . . . . . . 297.3 Non-wetland Site Associations occurrence by biogeoclimatic unit . . . . 235

figures. Distribution of biogeoclimatic units of the Boreal White and

Black Spruce zone in British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22. Hierarchical relationship between climatic-level and

site-level classifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83. Vegetation table comparing zonal sites for BWBS zone and

adjacent zones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.2 Physiographic units and subunits of northern British Columbia . . . . . . 85. A flowchart outlining the procedure for identifying site/seral

units as described in Sections 5..–5..3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.2 Key to differentiation of biogeoclimatic units of the BWBS . . . . . . . . . . 455.3 Vegetation table for comparison of vegetation on zonal sites of

the biogeoclimatic units of the BWBS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475.4 Slope position diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 505.5 Soil texturing key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 545.6 A key to the identification of relative soil moisture regimes . . . . . . . . . . 595.7 A key to the identification of relative soil nutrient regime . . . . . . . . . . . 606. Distribution of the BWBSdk within British Columbia . . . . . . . . . . . . . . 696.2 Distribution of the BWBSmk within British Columbia . . . . . . . . . . . . . . 936.3 Distribution of the BWBSmw within British Columbia . . . . . . . . . . . . . 96.4 Distribution of the BWBSwk within British Columbia . . . . . . . . . . . . . 476.5 Distribution of the BWBSwk2 within British Columbia . . . . . . . . . . . . . 736.6 Distribution of the BWBSwk3 within British Columbia . . . . . . . . . . . . . 987. Vegetation table of Bog and Coniferous Swamp Site Associations . . . . . 2237.2 Vegetation table of Fen, Marsh, and Low Shrub Bog Site Associations . 2277.3 Vegetation table of Flood and Tall Shrub Swamp Site Associations . . . . 2337.4 Vegetation table of Rock Outcrop, Grassland, and Brushland

Site Associations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

ix

1 INTRODUCTION

1.1 Objectives/Scope

This guide presents site identification information for ecosystems of the Boreal White and Black Spruce (BWBS) biogeoclimatic zone of British Columbia (Figure .).

The guide has four main goals:• to present descriptions of British Columbia’s boreal ecosystems in a

single guide;• to present a comprehensive revision to the classification of the BWBS;• to assist the user in classifying sites in the field; and• to provide insight into common site limitations and potential capa-

bilities related to the ecological conditions of the classified units to assist in preparing management prescriptions.

This guide represents a revision of existing classifications based on additions of new data and an inter-regional correlation of BWBS units. This guide replaces Land Management Handbook (LMH) 22 A Field Guide for Identification and Interpretation of Ecosystems of the North-east Portion of the Prince George Forest Region (DeLong et al. 990); the boreal sections of LMH 26, A Field Guide to Site Identification and Interpretation for the Prince Rupert Forest Region (Banner et al. 993); the BWBSdk section in LMH 54, A Field Guide to Site Identification and Interpretation for the North Central Portion of the Northern Interior Forest Region (DeLong 2004); and the Draft Field Guide Insert for Site Identification of Seral Populus Units of the Northeast Portion of the Prince George Forest Region.1

The main changes arising from revisions are:• merged BWBSdk2 and BWBSmw2 into BWBSmk because vegetation

similarities and climate data indicate that these regions are closely affiliated;

• renamed BWBSdk as BWBSdk and BWBSmw as BWBSmw, as there is now only one variant of each subzone;

• expanded classification of BWBSwk3 based on additional field sampling;

British Columbia Ministry of Forests. 2002. Draft field guide insert of seral Populus units of the northeast portion of the Prince George Forest Region. Victoria, B.C. Field Guide Insert. Unpubl. draft.

BWBS Zone Field Guide2

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RE .

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atic

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eal W

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• major plot additions to BWBSdk and BWBSmw based on extensive data compilation, (historical and recent collections);

• formal classification of mature broad-leaved ecosystems; and• revised system of numbering units based on province-wide correla-

tion.

See Appendix to determine equivalent previous biogeoclimatic and site units for new units described in this guide.

1.2 Regulatory and Standards Context

Section 6 of the Forest Planning and Practices Regulation (FPPR) (Province of British Columbia 2004a), requires forest stewardship plans (FSPs) to specify stocking standards for areas harvested under the plan. One of the factors that a person who prepares this plan should consider is that the stocking standards contain “the types of commercially valu-able and ecologically suitable species that should be established on the area” (Schedule (6) of the FPPR) (Province of British Columbia 2000, 2004b). To determine if a species is ecologically suitable for an area, the ecological characteristics of that area need to be determined. The gener-ally accepted method and current “best practice” of assessing these characteristics is biogeoclimatic site series mapping.

The Forest and Range Practices Act (FRPA) requires that a site plan be prepared for areas that will be harvested (Province of British Columbia 2002). This site plan must identify the standards units for the area and the stocking standards that apply to those units (Section 34 of FPPR) (Province of British Columbia 2004c). The surveys guidebook states that ecosystem classification plays an important role in developing stan-dards units (Province of British Columbia 2000). In addition, stocking standards, which are a required component of an FSP, are commonly defined by the biogeoclimatic and site units over which they apply.

Biogeoclimatic Ecosystem Classification (BEC) is also a standard that forms part of the many resource inventory procedures published by the provincial Resource Inventory Standards Committee (RISC), including standards for terrestrial ecosystem mapping and predictive ecosystem mapping and standards for mapping ecosystems at risk (www.ilmb.gov.bc.ca/risc/pubs/teecolo/index.htm). These procedures must be used for most inventory and environmental assessment projects in British Columbia.

http://www.ilmb.gov.bc.ca/risc/pubs/teecolo/index.htmhttp://www.ilmb.gov.bc.ca/risc/pubs/teecolo/index.htm


1.3 Other Sources of Information

Numerous reports on vegetation, soils, wildlife, and ecosystem descrip-tion and classification exist for the BWBS of British Columbia and adjoining area. Some of these references can be found in Section 8 (Literature Cited).

Information at the biogeoclimatic zone level is available in Ecosystems of British Columbia (Meidinger and Pojar [editors] 99). The Wetlands of British Columbia: A Guide to Identification (MacKenzie and Moran 2004) provides more information and tools for identification of the wetlands described in this guide.

The Field Manual for Describing Terrestrial Ecosystems (B.C. Ministry of Environment, Lands and Parks and B.C. Ministry of Forests 998) provides tools and useful information for assisting with collecting field data related to describing the ecosystems covered by this guide. Excel-lent references for plant identification, which complement this guide, are Plants of Northern British Columbia (MacKinnon et al. [editors] 9922) and Plants of the Western Boreal Forest and Aspen Parkland (Johnson et al. 995). When conducting a complete plant inventory Illustrated Flora of British Columbia should be used (Douglas et al. 998a, 998b, 999a, 999b, 2000, 200a, 200b, 2002). E-Flora BC (www.eflora.bc.ca/), which provides descriptions and colour images for most of British Columbia’s flora, is also a useful plant identification resource.

Additional information relating to BEC, including the most recent biogeoclimatic mapping, links to BEC field guides, and background information on the BEC system, is on the provincial Ecology program website at: www.for.gov.bc.ca/hre/becweb/.

1.4 Guide Content

This guide consists of eight sections. Following the introduction is a brief discussion of the classification system (Section 2). Sections 3 and 4 provide an overview of the BWBS in British Columbia, including vegetation, physiography, climate, and wildlife, as well as descriptions of climatic units. Section 5 contains procedures for site description and identification. Section 6 contains detailed information to assist with ecosystem identification within each of the BWBS subzones/variants

2 Revised second edition published in 999.

http://www.eflora.bc.ca/http://www.eflora.bc.ca/http://www.for.gov.bc.ca/hre/becweb/


found within the guide area, tools for identification of climatic and ecosystem units, descriptions of coniferous and broad-leaved ecosys-tem units, and comments relating to identification and management. Section 7 describes common non-forested ecosystems of the BWBS. Applicable literature is cited in Section 8.

The classification is based on 590 plots located in the BWBS within the Northern Interior Forest Region. These plots are generally well distrib-uted geographically (proportional to the size of the biogeoclimatic unit) except in areas with difficult access. Most ecosystem units are charac-terized by at least five plots, although certain less common ecosystems (e.g., on very dry or wet sites) may be characterized by fewer plots.

1.5 Training Courses

It is assumed that the user of this guide is familiar with the basic concepts and methods of site, soil, and vegetation evaluation and has completed the training programs offered by the Forest Service or educational institutions. These courses are offered annually in various locations within the Forest Region. For information about such training courses, please contact the Forest Research Section of the Northern Interior Forest Region, or the University of Northern British Columbia Continuing Studies Network, or check the following link www.for.gov.bc.ca/hre/becweb/resources/training/index.html.

2 BIOGEOCLIMATIC ECOSYSTEM CLASSIFICATION (BEC) SYSTEM

This section briefly describes the BEC system. For a more complete description refer to Ecosystems of British Columbia (Meidinger and Pojar [editors] 99) or Biogeoclimatic Ecosystem Classification in British Columbia (Pojar et al. 987).

2.1 An Overview of the BEC Classification System

The BEC system is a hierarchical classification scheme that combines three classifications: climatic (or zonal), vegetation, and site. For practi-cal purposes, users need only be concerned with the zonal and site clas-sifications (Figure 2.); the vegetation classification is used for ensuring consistency in naming conventions and for correlating ecosystems

http://www.for.gov.bc.ca/hre/becweb/resources/training/index.htmlhttp://www.for.gov.bc.ca/hre/becweb/resources/training/index.html


provincially, nationally, and internationally. The information presented in this guide will allow the user to apply BEC in the field. BEC principles evolved from the work of V.J. Krajina (965, 969) and are described in this section. The classification system was adapted for the province by the B.C. Ministry of Forests in the 970s (Pojar et al. 987). The objectives of the BEC system are: • to provide a framework for organizing ecological information and

management experience about ecosystems; • to promote further understanding of identified ecosystems and the

relationships among them; • to supply resource managers with a common language to describe

forest sites; and • to improve the user’s ability to prescribe and monitor treatment

regimes on a site-specific (ecosystem) basis.

2.2 Zonal (Climatic) Classification

Biogeoclimatic units are groups of ecosystems that have developed under the influence of the same regional climate. In the hierarchy of climatic units, the biogeoclimatic subzone is the basic unit. Subzones are grouped into zones, and divided into variants. Each biogeoclimatic subzone has a distinct climax (or near-climax) plant association on zonal sites. Zonal sites are defined as being those located in midslope positions, with deep, broadly loamy soils and mesic moisture regimes. The climax vegetation on zonal sites is considered to best reflect the regional climatic conditions of the subzone.

Each subzone has a distinctive sequence of related ecosystems rang-ing from dry to wet sites. Sites that are wetter or drier than the zonal ecosystem are influenced not only by the regional climate, but also by soil and topographic features at local scales. For example, in the Moist Warm subzone of the Boreal White and Black Spruce zone (BWBSmw), zonal sites are dominated by a white spruce canopy with a diverse, moderately well-developed understorey of shrubs and herbs; dry sites are dominated by a lodgepole pine canopy with an understorey dominated by a limited number of shrub species, grasses, and a mix of lichens and mosses; and wet sites in the same subzone (climate) have a white spruce overstorey with an understorey dominated by a diverse, well-developed shrub layer and a wide variety of herbs.

The biogeoclimatic variant was defined because subzones contain


considerable geographic variation. Variants reflect further differences in regional climate and are generally recognized for areas that are slightly drier, wetter, snowier, warmer, or colder than other areas in the subzone. For example, the Graham Wet Cool variant (BWBSwk2) of the BWBS is cooler than the Murray Wet Cool variant (BWBSwk) of the BWBS. These climatic differences result in corresponding differ-ences in vegetation, soil, and ecosystem productivity. The differences in vegetation are evident as distinct zonal climax or near-climax plant subassociations.

Subzones with similar climatic characteristics and zonal ecosystems are grouped into biogeoclimatic zones. A zone is a large geographic area with a broadly similar type of climate. A zone has typical patterns of vegetation and associated similarities in nutrient cycling and soil climate. Zones also have one or more typical zonal climax species of tree, shrub, herb, or moss.

Zones are usually named after one or more of the dominant climax spe-cies in zonal ecosystems and a geographic or climatic modifier (e.g., Bo-real White and Black Spruce zone). Zones are given a two- to four-letter code that corresponds to the name. For example, the Boreal White and Black Spruce zone is BWBS.

Subzone names are derived from classes of relative precipitation and temperature. Subzone codes correspond to the climatic modifiers (Table 2.). For example, the BWBSmw refers to the Moist Warm (mw) subzone of the BWBS zone. Variants are named by geographic area and numbered from south to north or, if the most southerly extent is similar, from west to east. Hence, the BWBSwk variant extends farther south than the BWBSwk2 variant.

Table 2. System of naming and coding interior biogeoclimatic units

ZONEpt

p = precipitation regime t = temperature regime x = very dry h = hot d = dry w = warm m = moist m = mild w = wet k = cool v = very wet c = cold v = very cold


2.3 Site Classification

Site series are the most commonly used units of site classification (Figure 2.) and are characterized within a biogeoclimatic unit. They are defined by using late seral or climax vegetation and represent site units having similar environmental properties and potential vegetation. The potential vegetation and selected environmental properties are used in this guide to characterize site series.

FIGURE 2. Hierarchical relationship between climatic-level (zonal) and site-level classifications. Updated from Pojar et al. (1987).

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Each biogeoclimatic unit has a characteristic sequence of site series ac-cording to relative soil moisture regime (RSMR) and, to a lesser degree, relative soil nutrient regime (RSNR)3 along with other environmental drivers such as flooding regime and cold air ponding. RSMR is a relative scale of “available water” for plant growth within the climate of the biogeoclimatic unit. An eight-class scale is used ranging from 0 or very xeric (bare rock) to 7 or subhydric (water tables at or near the surface year-round). RSNR is a relative scale of “available nutrients” for plant growth. A five-class scale ranging from A (very poor) to E (very rich) is used.

English names of one to four species are used to name site series, and tree species codes are usually substituted to shorten the name (e.g., SwPl – Soopolallie – Wildrye site series).

Similar plant communities can occur in different biogeoclimatic units, but the RSMR and RSNR that they represent may differ between subzones. These communities belong to the same grouping of site series that is collectively called a site association,4 such as:

BWBSwk1/Sb – Huckleberry – Lingonberry site series = BWBSwk1/104 BWBSwk3/Sb – Huckleberry – Lingonberry site series = BWBSwk3/103

Both of these site series belong to the same site association, so their climax vegetation is similar, but their occurrence in the landscape, site conditions, and seral vegetation patterns differ between the two biogeo-climatic units.

2.4 Unit Numbering Convention

Historically, each forested site series was given a two-digit numeric code with the “0” reserved for the zonal ecosystem and then other units numbered sequentially from driest (02) to wettest. With new revisions ongoing in many parts of the province, a new three-digit system has been introduced to minimize confusion arising from coding reclassified units. In the three-digit system, the first number indicates

3 The Site Identification section (Section 5.4) contains relative soil moisture and relative soil nutrient regime identification information.

4 Site associations are not clearly recognized in the classification presented in this manual, except through the site series names. They are defined in Pojar et al. (987).


the revision version (e.g., in this guide) and the second two numbers designate the site series with the “0” reserved for the zonal, 02–09 for units drier than zonal (ordered from driest to wettest, poorest to richest) and units 0 and greater applied to units wetter than zonal following the same numbering order. Units that are the same moisture regime as the zonal but poorer than zonal are coded as drier units. If the range in RSMR of a site series covers more than one class, the driest moisture regime is used for assignment. If future revisions are under-taken, all units will begin with a 2 (e.g., the zonal site will be coded as 20). Further label modifiers are: • BGC Phase: variability in mapped BEC variant (letter code);• Site Series Phase: same plant community, different site conditions; • Site Series Variation: different plant community, same site conditions

(see LMH 25, Field Manual for Describing Terrestrial Ecosystems [B.C. Ministry of Environment, Lands and Parks, and B.C. Ministry of Forests 998]).

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Seral ecosystems are numbered according to the site series with which the unit is affiliated, but are followed by a “” to designate that the unit is seral. The seral unit may then be further identified by the structural stage that the unit typically represents (see LMH 25, Field Manual for Describing Terrestrial Ecosystems [B.C. Ministry of Environment, Lands and Parks and B.C. Ministry of Forests 998] for structural stage descriptions); a stand composition modifier (B = broad-leaved, C = conifer, M = mixed); and a running number that is used to designate the seral vegetation community (seral plant association = seral varia-tion). Any one site series may have a number of seral variations within a structural stage/stand composition combination. The one that most commonly occurs will be seral variation , followed by the next most common, which would be seral variation 2, etc.

BWBS Zone Field Guide

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Appendix contains a table to convert units from the old system to the new system.

3 THE BWBS ZONE IN BRITISH COLUMBIA

The BWBS zone in British Columbia covers about 6 million ha and extends from the lee slopes of the Coast Mountains in the west to the Alberta border in the east, and from just south of 54° N latitude in the south to the Northwest Territories border in the north (Figure .). The BWBS is part of the circumpolar boreal zone, one of the world’s major ecological zones, covering 29% of the North American Continent, north of Mexico (Brandt 2009). Table 3. compares environmental charac-teristics for selected subzones of the biogeoclimatic zones that share a common border with the BWBS.

3.1 Vegetation

The BWBS zone is a mixture of two main ecosystems: upland forests and muskeg. Upland forests are most common in better-drained por-tions of the Alberta Plateau in the east and in mountainous parts of the zone in the west. Muskeg is most extensive on the poorly drained northeastern lowlands.

The BWBS contains several different upland forest types. The most common types are pure stands of trembling aspen, common in the southeast; mixed stands of trembling aspen, common in the northeast;


Tabl

e 3.

En

viro

nmen

tal c

hara

cter

istic

s of t

he B

WBS

zon

e an

d ad

jace

nt z

ones

in n

orth

ern

Briti

sh C

olum

bia

Zo

neC

hara

cter

istic

BW

BS

SWB

SBS

ESSF

IC

H

Biog

eocl

imat

ic

All

All

mc2

, mk1

, mk2

, m

c, m

v1, m

v2, m

v3,

mc2

, wc,

vc

units

con

side

red

w

k2, w

k3

mv4

, wv

for c

ompa

riso

n

Dis

trib

utio

n

rela

tive

to B

WBS

Occ

urs a

bove

the

Abu

ts th

e BW

BS a

t its

O

ccur

s abo

ve th

e

Abu

ts th

e BW

BSdk

BW

BS o

ver m

ost

sout

hern

ext

ent i

n BW

BS in

the

at

its s

outh

wes

tern

of it

s ext

ent n

orth

th

e Ro

cky

Mou

ntai

ns

sout

hern

par

t of

exte

nt a

long

the

of a

ppro

xim

atel

y

and

Foot

hills

, Roc

ky

its e

xten

t, so

uth

Isku

t Riv

er

56

° 30'

M

ount

ain

Tren

ch, a

nd

of a

ppro

xim

atel

y

Om

inec

a M

ount

ains

, 56

° 30'

and

at it

s wes

tern

ex

tent

in th

e St

ikin

e

and

Yuko

n Pl

atea

usEl

evat

ion

25

0–12

00

900–

1600

10

0–95

0 80

0–15

00

150–

1000

rang

e (m

)

Terr

ain

Mou

ntai

n an

d

Gen

tly ro

lling

Lo

wer

slop

es a

nd

Gen

tle to

stee

p,

Low

er sl

opes

and

pl

atea

u va

lleys

pl

atea

us, w

ide

floor

s of m

ajor

ro

cky

mou

ntai

n flo

ors o

f maj

or

in th

e w

est t

o

valle

ys to

riv

er v

alle

ys

slope

s riv

er v

alle

ys

rolli

ng o

r he

avily

gla

ciat

ed

depr

essio

nal

mou

ntai

n slo

pes

pl

ains

in th

e ea

st


Zo

neC

hara

cter

istic

BW

BS

SWB

SBS

ESSF

IC

H

Clim

ate

Nor

ther

n co

nti-

Con

tinen

tal

Sub-

cont

inen

tal,

Sub-

cont

inen

tal

Mild

subc

ontin

en-

ne

ntal

with

su

balp

ine

with

w

ith in

crea

sing

suba

lpin

e; lo

ng,

tal,

mod

erat

ed b

y

freq

uent

arc

tic

freq

uent

arc

tic

mar

itim

e in

fluen

ce

cold

, sno

wy

stro

ng c

oast

al

air m

asse

s; lo

ng,

air m

asse

s; lo

ng

tow

ard

the

coas

t;

win

ters

and

shor

t, in

fluen

ces;

mild

,

very

col

d w

inte

rs

very

col

d w

inte

rs

moi

ster

sum

mer

s co

ol, r

athe

r wet

m

oist

sum

mer

s

and

shor

t, dr

y,

and

very

shor

t, an

d m

ilder

win

ters

su

mm

ers

and

cold

, sno

wy

qu

ite w

arm

co

ol su

mm

ers

than

BW

BS

w

inte

rs

sum

mer

s

Tree

spec

ies

Maj

or c

onife

rous

Sw

, Pl,

Bl, S

ba

Sw, S

b, P

l, Bl

Sx

w, P

l, Sb

, Bl

Se, B

l, Pl

, Sb,

H

w, B

l, Sx

w, P

l t

rees

(Hm

, Hw

) M

ajor

bro

ad-

At,

Acb

or A

ct,

Will

ows,

A

t, Ep

, Act

At,

Act

, Ep

lea

ved

tree

s Ep

A

t, A

cb

a Tr

ee sp

ecie

s cod

es: A

cb =

bal

sam

pop

lar,

Act

= c

otto

nwoo

d, A

t = tr

embl

ing

aspe

n, B

l = su

balp

ine

fir, E

p =

pape

r bir

ch, H

m =

mou

ntai

n he

mlo

ck,

Hw

= w

este

rn h

emlo

ck, L

t = ta

mar

ack,

Pl =

lodg

epol

e pi

ne, S

b =

blac

k sp

ruce

, Se

= En

gelm

ann

spru

ce, S

w =

whi

te sp

ruce

, Sxw

= h

ybri

d w

hite

/En-

gelm

ann

spru

ce.


and mixed stands of lodgepole pine and white spruce, common in the western and montane areas of the zone. Open lodgepole pine and lichen forests occupy drier sites, whereas poorly drained wet sites give rise to communities of black spruce and moss. White spruce and balsam pop-lar flourish on rich, well-drained river floodplains, which contain the most productive forests of the zone. Other tree species that have more limited ranges within the guide area are discussed in the introductory comments for each biogeoclimatic unit.

The term “muskeg” describes the peatland combination of bogs and nutrient-poor fens that cover extensive parts of northeast British Columbia. The most common trees in this ecosystem are stunted black spruce and tamarack. Muskeg occurs over deep layers of peat where permafrost is often found.

The BWBS zone contains several other minor but important ecosys-tems: in the northeast, nutrient-rich swamps and fens are dominated by tamarack, sedges, and brown mosses; boreal grassland and scrub communities occupy steep, south-facing slopes; and small but produc-tive marsh and shallow lake ecosystems are found throughout the zone. Figure 3. compares characteristic vegetation of the BWBS with that of selected areas of adjacent zones (listed in environmental summary – Table 3.).

3.2 Disturbance

Fire is the key stand-replacing disturbance agent operating in the BWBS zone, with the exception of flooding along broad fluvial terraces adjacent to larger rivers. The disturbance rate from fire is generally esti-mated to be about % of the total forested area per year (i.e., fire cycle of 00 years), but will vary in particular locations depending on climatic and topographic factors. Historically, large wildfires (> 000 ha) domi-nated the landscape, and upland sites were regenerated quickly by dense trembling aspen, trembling aspen and spruce, or lodgepole pine, result-ing in large patches of relatively even-aged forests. On wetlands, black spruce, tamarack, Alaska paper birch, and occasionally white spruce regenerate after fire. Initially, wetland stands tend to be very open, filling in over time, except in upland transition areas where stands are often denser. In small areas where past fires were intense, stands may regenerate to willow or alder.


During stand development, increasing amounts of white spruce and black spruce will occur in many stands originally dominated by trem-bling aspen or lodgepole pine. This increase occurs more rapidly and these species become a more dominant portion of the canopy on wetter sites. Post-fire stands are very dense except on the wettest sites, and self thin over time.

Tomentosus root disease is thought to be a key disturbance agent af-fecting white spruce and in some localized areas may cause conversion from spruce-dominated stands to aspen-dominated stands over the course of 20–40 years. Eastern spruce budworm may also cause signifi-cant mortality of mature or immature spruce and lead to conversion of mixed to almost pure aspen stands.

Floodplains are often extensive along major rivers in the BWBS. Seasonal inundation is common in these areas, but stand replacement flood cycles are unknown. Where stand replacement occurs, the typical floodplain succession pattern shifts from willow to cottonwood on the lower benches and from cottonwood to spruce on the higher benches.

Stand ages rarely exceed 200 years. Relatively large patches (> 00 ha) of older forest (40–80 years) that were found scattered across the landscape have been reduced by harvesting over the past 40–50 years. Although patches of old forest (> 40 years) likely always occurred in the landscape, their position would have moved around over time due to regular disturbances.

3.3 Physiography and Soils

The distribution and extent of boreal forests in northern British Co-lumbia is to a large degree controlled by physiography. The BWBS zone is a lowland to montane zone found at elevations below 200 m; it is extensive on the lowlands and subdued terrain of the Alberta Plateau in the northeast corner of the province but becomes a valley-bottom phenomenon in the more mountainous western extent.

Holland (976) divides northern British Columbia into 3 physiographic units; most of these are further divided into subunits (Figure 3.2). This framework will be used to describe the diverse physiography of north-ern British Columbia from east to west. Further information relevant to the physiography and soils of British Columbia’s boreal forest can be


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nits

: BW

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SBS*

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ESSF

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ts:

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gla

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id w

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volu

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tens

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anic

ulat

a ■■

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uebe

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f Py

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ia

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nk w

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ium

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alis

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er

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podi

um a

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ca c

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reen


FIGU

RE 3

. Ve

geta

tion

tabl

e co

mpa

ring

zona

l site

s for

BW

BS z

one

and

adja

cent

zon

es.

Fe

stuc

a al

taic

a

■■■

A

ltai f

escu

e

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trum

nig

rum

■■■

cr

owbe

rry

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bus p

edat

us

■■■

■■■

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fiv

e-le

aved

bra

mbl

e

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opte

ris e

xpan

sa

■

spin

y w

ood

fern

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ymno

carp

ium

dry

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ris

*

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oa

k fe

rn

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s an

d H

yloc

omiu

m sp

lend

ens

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st

ep m

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ens

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rozi

um sc

hreb

eri

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re

d-st

emm

ed fe

athe

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s

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um c

rista

-cas

tren

sis

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ight

’s pl

ume

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ltige

ra a

phth

osa

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fr

eckl

e pe

lt

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idia

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rique

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ectr

ified

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’s-ta

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oss

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ta fo

r nor

ther

n su

bzon

es o

nly.

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nly

abun

dant

in th

e w

k va

rian

ts in

the

BWBS

.


found in Annas (997), Valentine et al. (editors, 978), Pojar et al. (983), Meidinger and Lewis (983), and Meidinger et al. (986).

3.3. Alberta Plateau

The Alberta Plateau is an extensive area of low relief resulting from the erosion of sedimentary sandstones and shales. This large plateau lies mostly between 900 and 200 m in elevation but is incised by the Liard and Peace Rivers and their tributaries to elevations as low as 300 m.

The Alberta Plateau represents the most extensive area of the BWBS zone in British Columbia. The BWBSmk and BWBSmw subzones domi-nate the plateau area with the BWBSwk occurring at elevations above 950–050 m in the west near the Rocky Mountain Foothills. Upland trembling aspen or mixed trembling aspen–white spruce forests domi-nate the southern Alberta Plateau, while the Fort Nelson Lowlands por-tion of the plateau that lies mostly below 600 m in the northeast corner of the province is dominated by poorly drained black spruce muskeg.

FIGURE 3.2 Physiographic units and subunits of northern British Columbia (after Holland 1976).


Fine-textured Luvisols dominate in the southern half of the plateau where morainal and (glacio)lacustrine parent materials occur, grad-ing to Gleysols where drainage is impeded. Organic soils (Mesisols and Fibrisols) dominate the Fort Nelson Lowlands where discontinu-ous permafrost occurs north of 58º N latitude. Brunisols occur on coarser-textured glaciofluvial deposits, and Regosols dominate the river floodplains as well as the (often unstable) valley sides above floodplains. Limited areas of grassland Chernozems and saline soils (Solonetzic Order) occur along the Peace River near the Alberta border. Significant portions of the Peace River lowlands near larger centres such as Fort St. John and Dawson Creek have been converted to agriculture.

As is typical throughout the boreal forest, there is a tendency for Hemi-mor humus forms, derived mainly from feathermosses, to build up to considerable thicknesses as stands age and the broad-leaved tree com-ponent drops out. Repeated fire disturbance plays an important role in controlling this “smother moss” build-up that insulates the soil surface, triggering a gradual decline in soil temperature, drainage, nutrient turnover, and tree productivity, and eventually leading to bog develop-ment. This phenomenon, called paludification, is especially evident on cooler aspects across the north.

3.3.2 Rocky Mountain Foothills and Rocky Mountains

The transition from the flat lying/gently dipping sedimentary rocks of the Alberta Plateau to folded and faulted sedimentary rocks (lime-stones, siltstones, sandstones, and shales) underlying the slopes to the west delimits the boundary of the Rocky Mountain Foothills. The foothills stretch from the Liard River in the north, southeast to the Alberta border and beyond. The foothills give way to the more rugged Rocky Mountains to the west that are dominated by older sedimentary and metamorphic rocks, mainly limestones, quartzites, schists, and slates. The Rocky Mountain Foothills rise in elevation from about 000 m in the east to summits and ridges in the west with elevations of 800 to over 200 m. The Rocky Mountains to the west consist of the rugged Muskwa Ranges north of the Peace River, where peaks above 2400 m are typical, and the more subdued Hart Ranges in the south.

The BWBS zone (mainly the BWBSwk) becomes more restricted in the foothills. It extends onto slopes of the eastern flanks to about 200 m


and penetrates limited distances up some of the major river valleys that originate in the Rocky Mountains and flow east onto the Alberta plateau (e.g., Murray, Pine, Sukunka, Graham, Halfway, Sikanni Chief, Prophet, and Muskwa Rivers and the Peace Reach of Williston Lake). The BWBSdk occurs in the river valleys (e.g., the Akie, Kwadacha, Warneford, and Gataga Rivers) that drain the Rocky Mountains to the west into the Rocky Mountain Trench. The BWBSmk occurs in the valley bottoms of the northern Rockies where they drain into the Liard River. Near the divide of the Rocky Mountains, the BWBS gives way to the Sub-Boreal Spruce (SBS) zone. At elevations above 200 m in the foothills and the Rockies, the BWBS gives way to the Engelmann Spruce – Subalpine Fir (ESSF) zones in the south, and the Spruce – Willow – Birch (SWB) zone in the north.

Medium- to fine-textured glacial till dominates valley bottoms where the BWBS occurs. Glacial meltwaters flowing east out of the Rockies deposited coarser-textured glaciofluvial deposits in some lower slope and valley-bottom locations. Localized, medium- to coarse-textured colluvial and fluvial deposits also occur throughout.

3.3.3 Liard Plateau

The Liard Plateau lies north of the Rocky Mountains with the south-erly extent of the Liard River forming the boundary. This plateau is underlain by folded sedimentary rocks, but, in contrast to the Rocky Mountains, consists of rounded and flat-topped summits lying mostly below 500 m in elevation. The Liard River has carved through the sedimentary bedrock to the south of the Plateau to elevations of 450 m, creating the Grand Canyon of the Liard. The BWBS extends through the Liard River Corridor in the southern portion of the plateau and penetrates up the Grayling, Scatter, and Crow Rivers that incise the plateau farther north. The BWBSmk occurs below 900–000 m and the BWBSwk occurs above 900 m in the eastern portions. The SWB zone is extensive on the Liard Plateau at elevations above 000–00 m. Medium- to fine-textured Luvisols derived from glacial till dominate the BWBS portion of this landscape.

3.3.4 Liard Plain

The Liard Plain is an extensive area of low relief west of the Liard


Plateau, within the drainage of the Liard River. With elevations largely between 750 and 050 m, this area is almost exclusively comprised of forests of the BWBS zone (BWBSmk subzone). This plain is surrounded on all sides by higher mountain and plateau areas. It is underlain by sedimentary bedrock, but the surface is shaped largely by glacial fea-tures and deposits such as eskers, drumlinized till, and shallow lakes. Coarser-textured Brunisols are associated with the eskers and other glaciofluvial deposits, while Luvisols are typical of the fine- to medium-textured till and glaciolacustrine deposits.

3.3.5 Northern Rocky Mountain Trench

The Northern Rocky Mountain Trench is a straight, narrow valley 3–4 km wide that extends from the headwaters of the Parsnip River in the south to the Liard Plain in the north along the western edge of the Rocky Mountains. Valley-bottom elevations range from 700 m in the north and south to a little more than 000 m at the divide (Sifton Pass) between the northward-flowing Kechika River and the southward-flow-ing Fox and Finlay Rivers.

The BWBS (mk in the north, dk in the south) extends from the Liard Plain southward in the trench to the north end of Williston Lake, where it abuts the SBS zone in the valley bottom. The BWBS also extends up several river valleys draining the Rocky Mountains to the east and the Cassiar/Omineca Mountains to the west, such as the Ingenika, Finlay, Frog, Turnagain, Gataga, and Akie Rivers. The floor of the trench con-tains deep morainal as well as fluvial and glaciofluvial deposits.

3.3.6 Cassiar and Omineca Mountains

The mountains that rise up east of the Northern Rocky Mountain Trench and the Liard Plain are divided into two ranges: the Cassiar Ranges in the north and the Omineca Ranges south of the Finlay River. The Cassiar Mountains consist of folded sedimentary (includ-ing limestone and slate) and volcanic rocks as well as a core of granitic rock called the Cassiar Batholith where the highest peaks occur (e.g., Sharktooth Mountain west of Dall Lake at 2670 m). The BWBS zone occupies several large glacial valley systems within the Cassiar Ranges below 00–200 m elevation, including the Turnagain and Frog Rivers and their tributaries. The SWB and Boreal Altai Fescue Alpine (BAFA) zones dominate both the Cassiar and Omineca Ranges.


The Omineca Mountains extend south from the Cassiar Mountains on the west flank of the trench to the southern end of Williston Lake, where they grade into the Nechako Plateau. These mountains are simi-lar in lithology to the Cassiar Mountains, with the largest peaks in the north being of granitic origin (e.g., Mount Cushing at 2650 m). Large river valleys such as the Finlay, Ingenika, Mesilinka, Osilinka, and Omineca contain significant areas of BWBSdk. In the south the BWBS gives way to the SBS zone and at higher elevations the ESSF replaces the SWB. The most southerly extent of the BWBS zone in the Omineca Mountains is at Germansen Lake.

Soils in the valleys of both the Cassiar and Omineca Mountains are derived mostly from glacial till as well as colluvium on the valley sides and glaciofluvial and fluvial materials along the rivers.

3.3.7 Stikine Plateau

To the west of the Cassiar and Omineca Mountains lies the Stikine Pla-teau, a large area of dissected plateau country in the rainshadow of the Coast Mountains. This area is drained mostly by the Stikine and Taku Rivers and their tributaries. For the most part this area lies at or above 500 m in elevation but generally below the level of the surrounding mountains. The Stikine Plateau is subdivided into seven geographically and geologically distinct subunits: the Tahltan Highlands in the west, which is transitional to the Coast Mountains; the central Taku, Nahlin, and Klastline Plateaus; and the eastern Kawdy, Tanzilla, and Spatzizi Plateaus. Some units, such as the Taku Plateau and Tahltan Highlands, are more incised and dissected compared with the gentler relief of the Nahlin, Kawdy, and Spatzizi Plateaus. The highest peaks occur in the Tahltan Highlands, the most impressive of which is the shield volcano of Mount Edziza rising to 2790 m, with the brilliantly coloured Spec-trum Range extending to the south. The Grand Canyon of the Stikine River slices 300 m through the Stikine Plateau for 75 km upstream of Telegraph Creek and separates the Klastline and Tanzilla Plateaus.

Sedimentary and volcanic rocks dominate throughout the Stikine Plateau. Major centres of past volcanic activity include Mount Edziza, Level Mountain, and the tuyas of the Kawdy Plateau. With much of the Stikine Plateau surface occurring above 500 m in elevation, it is domi-nated by the SWB and BAFA zones. The BWBSdk occurs below 200 m


in the major river valleys that dissect the plateau, including the Stikine, Spatzizi, Iskut, and Tanzilla in the south and the Nakina, Inklin, Sheslay, Nahlin, and Dease in the north. These valleys are dominated by glacial till and fluvial and glaciofluvial parent materials with some colluvial materials associated with the steeper terrain. Fine-textured Luvisols dominate on the tills, and coarser-textured Brunisols (and Regosols) on the fluvial and colluvial parent materials.

Where major river valleys (e.g., the Stikine, Iskut, and Inklin/Taku Rivers) reach the western edge of the Plateau and enter the Coast Mountains, the BWBS zone gives way to the SBS and Interior Cedar – Hemlock (ICH) zones and eventually the CWH zone over a fairly rapid continental/maritime climate transition.

3.3.8 Yukon Plateau

The Yukon Plateau occurs to the northwest of the Stikine Plateau. In British Columbia, it is dominated by the central Teslin Plateau, which is flanked to the west by the Tagish Highland and to the east by the Nisutlin Plateau. The Yukon Plateau lies in the rainshadow of the St. Elias Mountains and Boundary Ranges to the west. Bedrock geology is dominantly sedimentary and volcanic with a large area of igneous rock occurring east of Atlin Lake.

The Teslin Plateau is a gently sloping and dissected upland area that stretches from Atlin Lake in the west to Teslin Lake in the east. Mountains rise to 200 m and though much of the terrain is above 00 m, where the SWB and BAFA zones dominate, significant areas of BWBSdk occupy the broad valley bottoms of Atlin Lake and Teslin Lake and the narrower valleys in between. Glacial till, drumlin features, and lakes formed in glacial depressions characterize the Teslin Plateau where Luvisols (and Brunisols) are the typical soils.

On the Nisultan Plateau to the east of Teslin Lake and in the Swift River and Jennings River drainages, the relatively low-lying terrain gives rise to extensive areas of BWBSdk. The Tagish Highland occurs north of the Taku River in the western Yukon Plateau and represents a narrow transition between the Teslin Plateau and the Coast Mountains, where dissection increases and mountain peaks are somewhat higher. Here the BWBSdk occurs extensively in the glacial till–dominated valley bot-toms of Tagish and Atlin Lakes.


3.3.9 Skeena Mountains

The Skeena Mountains occur south of the Stikine Plateau and constitute the major mountainous area in the northern Interior of British Colum-bia, extending approximately 400 km south to the Bulkley Valley at the northern edge of the Interior Plateau. The Skeena Mountains form the headwaters of three major northern river systems: the Skeena, Stikine, and Nass drainages. The BWBS zone extends only into the extreme northern portion of the Skeena Mountains as narrow fingers in the upper Klappan and Spatzizi Rivers. South of these areas, the ESSF, ICH, and SBS zones dominate below the extensive alpine zone in the Skeena Mountains.

3.3.0 Coast Mountains and St. Elias Mountains

North of the Nass River, the Coast Mountains are represented by the Boundary Ranges: rugged, granitic, ice-capped mountains that extend the length of the British Columbia–Alaska border. Maritime influences extend up the major river valleys (Iskut, Stikine, and Taku Rivers) that dissect the Boundary Ranges, and thus the BWBS zone does not pen-etrate west into the Coast Mountains. In the extreme northwest corner of the province (the Haines Triangle), however, where the Alsek and Tatshenshini Rivers flow through the ice-draped St. Elias Mountains, a unique subzone of the BWBS occurs along the valley bottoms. This very wet, cool (BWBSvk) subzone experiences strong maritime/conti-nental gradients with heavy snowpacks and strong winds. The Bound-ary Ranges and St. Elias Mountains, both heavily influenced by moist Pacific air masses, create a rainshadow effect that yields the relatively dry boreal climate typical of the Yukon and Stikine Plateaus to the east.

3.4 Climate of the Boreal Forest

Most of the BWBS zone experiences a continental climate, dominated by both continental arctic and continental polar air masses (Ahrens 994). This zone is characterized by long, cold winters and short grow-ing seasons (Meidinger and Pojar [editors] 99). The mean annual temperature ranges from –2.4 to 3.6°C and annual precipitation ranges between 34 and 897 mm (Table 3.2). The BWBS is generally drier, especially in the winter, and warmer in the summer than the adjacent


portions of the zones (Table 3.2). The BWBS is also colder in the winter than the adjacent portions of lowland zones (Table 3.2).

Approximately 32% of precipitation falls as snow, which may seem low considering that any day of the year can see temperatures below freezing. In the portion of the BWBS east of the Rockies, winters generally receive the least amount of precipitation due to cold, dry, arctic high-pressure systems. The inter-annual variability of the Arctic Oscillation controls the amount and the extent of cold arctic air in the winter. Summer rain makes up most of the precipitation and is typically double any other season. This is due mainly to moist weather systems from the Pacific Ocean flowing across the Rocky Mountains, but also from temperatures warm enough to generate convective showers and thundershowers. When inverted troughs of low pressure from Alberta force air to flow west and condense against the mountains, they bring high precipitation amounts in short time periods. Areas of the BWBS in and west of the Rocky Mountains typically experience milder condi-tions in the winter but are cooler in the summer due to the influence of the mountainous topography, which blocks the influence of the arctic fronts in winter but allows cold air to seep down from higher elevations in the summer. In this area, annual precipitation is comprised more evenly of rain and snow; however, rain still dominates as most precipi-tation falls in the summer.

Temperatures in the BWBS can be extreme. Fort Nelson, for example, experiences one of the largest spreads in temperature of the province, with summer highs reaching above 30°C and winter lows commonly below –40°C (Heidorn 2004). The climate station at the Fort Nelson air-port recorded both the highest extreme maximum temperature (36.7°C, 942) and the lowest extreme minimum temperature (–5.7°C, 947) for the BWBS (Table 3.3). The warmest month is July, in which mean temperatures range from .7 to 6.7°C. The coldest month is January; mean temperatures range from –23.8 to –7.4°C. The temperature spread throughout the year is less extreme in western portions of the BWBS.

Climate conditions of the BWBS subzones from 97 to 2000 are described in Table 3.4. The warmest and the wettest subzone is the BWBSwk, with a mean annual temperature of 2.9°C and mean annual precipitation of 743 mm. The coldest subzone is the BWBSmk, with a


TABL

E 3.

2 Co

mpa

rison

of c

limat

e va

riabl

es fo

r the

BW

BS z

one

and

adja

cent

por

tions

of z

ones

in n

orth

ern

Briti

sh C

olum

biaa

Clim

ate

char

acte

rist

ics

BW

BSb

SBSb

SW

Bc

ESSF

c IC

Hc

Ann

ual p

reci

pita

tion

(mm

) M

ean

535

708

778

1125

10

14

SDd

96

257

292

788

375

R

ange

34

1–89

7 46

3–18

93

496–

1691

45

5–32

26

580–

2445

Mea

n gr

owin

g se

ason

M

ean

317

296

408

424

362

prec

ipita

tion

(mm

) SD

48

67

11

8 19

6 94

(May

–Sep

tem

ber)

R

ange

14

5–44

3 19

2–54

0 23

0–59

0 19

3–94

2 25

3–74

2A

nnua

l sno

wfa

ll (c

m)

Mea

n 16

9 31

6 36

4 56

8 43

3

SD

41

166

223

479

184

R

ange

11

0–33

2 14

8–10

51

161–

1019

16

3–24

24

183–

938

Ann

ual t

empe

ratu

re (°

C)

Mea

n 1.7

2.

2 -1

.0

1.1

2.6

SD

1.0

0.

6 1.1

1.6

1.7

R

ange

-2

.4–3

.6

0.7–

4.2

-2.5

–1.1

-3.5

–6.6

-0

.7–6

.3M

ean

war

mes

t mon

th

Mea

n 14

.7

13.8

11

.6

12.3

13

.5te

mpe

ratu

re (°

C)

SD

0.8

0.8

1.4

1.6

1.4

Ran

ge

11.7

–16.

7 11

.4–1

5.9

9.4–

13.5

7.

5–16

.6

10.3

–16.

2M

ean

cold

est m

onth

M

ean

-12.

4 -1

0.5

-12.

9 -1

0.0

-8.9

tem

pera

ture

(°C

) SD

2.

5 1.0

1.3

2.

0 2.

5

Ran

ge

-23.

8–(-

7.4)

-1

4.4–

(-7.

7)

-16.

8–(-

11.0

) -1

4.2–

(-4.

4)

-13.

1–(-

3.8)

Extr

eme

min

imum

M

ean

-44.

2 -4

1.9

-44.

3 -4

0.9

-38.

4te

mpe

ratu

re (°

C)

SD

2.3

1.3

1.2

2.6

4.0

R

ange

-4

9.7–

(-37

.3)

-46.

4–(-

38.0

) -4

7.3–

(-42

.5)

-45.

3–(-

31.5

) -4

3.9–

(-29

.2)


Clim

ate

char

acte

rist

ics

BW

BSb

SBSb

SW

Bc

ESSF

c IC

Hc

Gro

win

g de

gree

day

s M

ean

1451

11

47

1737

12

50

979

(< 0

°C)

SD

288

130

191

286

308

R

ange

93

5–26

82

870–

1730

14

17–2

161

422–

2031

41

1–15

85G

row

ing

degr

ee d

ays

Mea

n 11

49

1016

63

0 78

5 99

7(>

5°C

) SD

14

0 12

9 20

4 25

6 24

9

Ran

ge

702–

1421

66

9–13

65

382–

946

181–

1711

46

8–15

83D

ate

of g

row

ing

degr

ee

Mea

n M

ay 16

M

ay 2

6 Ju

n 12

Ju

n 06

M

ay 2

5da

y >

5°C

reac

hes 1

00

SD

7 8

10

15

13(b

udbu

rst)

R

ange

M

ay 7

–Jun

8

May

10–J

un 19

M

ay 2

7–Ju

n 26

A

pr 2

5–Ju

l 25

Apr

28–

Jun

26Fr

ost-

free

per

iod

M

ean

92

83

56

73

95(d

ays)

SD

9

12

19

27

22

Ran

ge

54–1

11

50–1

08

13–8

8 2–

161

48–1

43N

umbe

r of f

rost

-fre

e

Mea

n 15

5 15

4 12

4 14

3 16

4da

ys

SD

8 9

15

23

26

Ran

ge

126–

175

128–

177

102–

153

78–2

27

94–2

19

a Bi

ogeo

clim

atic

uni

ts u

sed

with

in th

e ad

jace

nt z

ones

as f

ollo

ws:

SBS

(Sub

-Bor

eal S

pruc

e) =

mc2

, mk

, mk2

, wk2

, wk3

; SW

B (S

pruc

e –

Will

ow

– Bi

rch)

= d

k, m

k, v

k; E

SSF

(Eng

elm

ann

Spru

ce –

Sub

alpi

ne F

ir =

mc,

mv

, mv2

, mv3

, wv;

ICH

(Int

erio

r Ced

ar –

Hem

lock

) = m

c2, w

c, v

c.

b U

pdat

ed fr

om R

eyno

lds (

989

) for

97

–200

0 cl

imat

e no

rmal

s usi

ng C

limat

eBC

(Wan

g et

al.

2006

).c

Supp

lem

ente

d Re

ynol

ds (

989)

wea

ther

stat

ion

loca

tions

with

add

ition

al d

ata.

d

Stan

dand

dev

iatio

n of

the

mea

n.


TABL

E 3.

3 BW

BS 19

71–2

000

clim

ate

norm

als:

Env

ironm

ent C

anad

a w

eath

er st

atio

ns w

ith W

orld

Met

eoro

logi

cal O

rgan

izat

ion

Stan

dard

sa

El

evat

ion

M

ATb

Extr

eme

Extr

eme

MA

Pb

Ann

ual

Ann

ual

DD

Stat

ion

(m)

Subz

one

(°C

) m

ax (°

C)

min

(°C

) (m

m)

rain

(mm

) sn

ow (c

m)

> 5

°C

Atli

n 64

7 dk

0.

5 30

.6

-50.

0 34

7 19

2 15

5 83

0D

awso

n C

reek

A

655

mw

1.6

34

.5

-49.

2 48

2 32

6 17

4 12

36D

ease

Lak

e 80

7 dk

-0

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35.3

-5

1.2

426

265

218

774

Fort

Nel

son

A

382

mk

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36

.7

-51.7

45

2 32

0 17

8 13

20Fo

rt S

t. Jo

hn A

69

5 m

w

2.0

33.6

-4

7.2

466

313

186

1312

Ger

man

sen

Land

ing

766

dk

1.0

34.5

-4

8.8

538

321

243

968

a En

viro

nmen

t Can

ada

(200

8).

b M

AT

= m

ean

annu

al te

mpe

ratu

re, M

AP

= m

ean

annu

al p

reci

pita

tion.


TABL

E 3.

4 Su

mm

ary

of c

limat

e da

ta fo

r bio

geoc

limat

ic u

nits

with

in th

e BW

BS z

one

of n

orth

ern

Briti

sh C

olum

biaa

Clim

ate

char

acte

rist

ics

BWBS

dk

BWBS

mk

BWBS

mw

BW

BSw

k1

BWBS

wk2

BW

BSw

k3

Ann

ual p

reci

pita

tion

M

ean

498

499

515

743

571

570

(mm

) SD

b 85

46

64

62

43

10

R

ange

34

1–64

4 43

1–58

4 42

4–74

9 64

4–89

7 48

5–62

5 56

0–57

9M

ean

grow

ing

seas

on

Mea

n 26

6 32

2 31

5 38

9 39

5 39

8pr

ecip

itatio

n (m

m)

SD

55

51

27

21

37

10(M

ay–S

epte

mbe

r)

Ran

ge

145–

443

229–

416

266–

404

356–

421

317–

428

388–

407

Ann

ual s

now

fall

(cm

) M

ean

189

155

156

241

152

156

SD

47

40

26

35

24

4

R

ange

11

0–25

8 12

1–24

8 11

0–24

2 19

7–33

2 13

4–21

0 15

2–15

9

Ann

ual t

empe

ratu

re

Mea

n 1.2

-0

.6

1

a field guide to ecosystem identiﬁ cation for the …a field guide to ecosystem identiﬁcation...

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