Ecosystem Classification and Interpretation of the c.3 Sub-Boreal Spruce Zone, Prince Rupert Forest Region, British Columbia by J. Pojar', R. Trowbridge', and D. Coates2 'Ministry of Forests 2Ministry of Forests Research Section Silviculture Section Prince Rupert Forest Region Prince Rupert Forest Region Bag 5000 Bag 5000 Smithers. B.C. Smithers, B.C. VOJ 2N0 VOJ 2N0 Province of British Columbia Ministry of Forests ACKNOWLEDGEMENTS Numerous individualsassisted in the various phases ofthis report. D.J. Wilford managed theprogram in its first few years. K. Awmack, A. Banner, M. Blouw, W. Chapman, A. Deas, S. Haeussler, D. Holmes, R. Laird, A. Macadam, K. McKeown, M. O'Neill, L. Ricciotti, 6. Robinson, J. Schwab, 0.Wilford, and D. Yolehelped carry out field work. S. Lindeburghand B.M. Geislercontributed tothe Interpretations sections of theguide. J. van Barneveld and 0. Meidingerreviewed the manuscript and provided many usefulsuggestions. G. Bishop, P. Frank, P. Nystedt,and P. Sowden did most ofthe illustrations. F. Boasand J. Godfrey identified some ofthe bryophytes. Final editing and preparationof the report was by W. Taylor and K. McKeown. M. Romeo, and C. Huismanand J. Taekema did the typing andword processing, respectively. TABLE OF CONTENTS Page 1.0 INTRODUCTION ......................................................... 1 2.0 OBJECTIVES ........................................................... 4 3.0 PRINCIPLES AND PHILOSOPHY ............................................ 5 3.1 Ecosystem ....................................................... 5 3.2 Zonal Ecosystem ................................................. 8 3.3 Climax and Succession ........................................... 9 3.3.1 Climax ................................................... 9 3.3.2 Types ofclimax .......................................... 10 3.3.3 Succession ............................................... 11 3.3.4 Sub-borealclimax and succession ......................... 11 3.3.5 Potentialclimax and succession .......................... 12 3.4 EcosystemLevels ofClassification .............................. 13 3.4.1 Ecosystemtype ........................................... 14 3.4.2 Ecosystem association.................................... 14 3.4.3 Ecosystemsubassociation ................................. 16 3.4.4 Ecosystem association phase .............................. 17 3.5 BiogeoclimaticLevels of Classification ......................... 18 3.5.1Biogeoclimatic subzone ................................... 19 3.5.2 Biogeoclimaticvariant ................................... 19 3.5.3 Biogeoclimatic phase ..................................... 20 3.5.4 Biogeoclimatic zone ...................................... 21 4.0 METHODS .............................................................. 21 4.1 Plot Sampling ................................................... 23 4.2 Analysis ........................................................ 24 4.3 Mapping ......................................................... 28 5.0 STUDYAREA ........................................................... 28 5.1 Physiography .................................................... 29 5.2 SurficialDeposits .............................................. 32 5.2.1 Glacial till ............................................. 33 5.2.2 Glaciofluvialdeposits ................................... 35 5.2.3 Glaciolacustrinedeposits ................................ 36 5.2.4 Fluvialdeposits ......................................... 36 5.2.5 Colluvial. deposits ....................................... 36 5.2.6 Organicdeposits ......................................... 37 5.3 BedrockGeology ................................................. 37 5.4 Climate ......................................................... 38 5.4.1 General .................................................. 38 5.4.2 Sub-borealclimate ....................................... 40 5.5 Vegetation ...................................................... 44 5.5.1 Uplandforest ............................................ 44 5.5.2 Wetlands ................................................. 45 5.5.3 Aquaticvegetation ....................................... 46 5.5.4 Grasslandand scrub ...................................... 46 5.6 Soils............................................................ 46 5.6.1 Soilsdeveloped on glacial till .......................... 47 5.6.2 Soilsdeveloped on glaciofluvialdeposits ................ 48 5.6.3 Soilsdeveloped on fluvial deposits ...................... 48 5.6.4 Soilsdeveloped on colluvial deposits .................... 49 5.6.5 Organicsoils ............................................ 49 5.6.6 Organicmatter accumulation in mineralsoils ............. 49 5.6.7 Humus .................................................... 50 6.0 MODIFYINGFACTORS .................................................... 50 6.1 Settlement ...................................................... 50 6.2 Roads ........................................................... 53 6.3 Hydroelectric Development ....................................... 54 6.4 Grazing ......................................................... 54 6.5 ~ogging......................................................... 55 6.6 Fire............................................................ 57 7.0 SUB-BOREALSPRUCE ZONE ............................................... 58 7.1 Subzones ........................................................ 58 7.1.1 SBSa (Pine - sprucesubzone) ............................. 59 7.1.1.1 Ecologicalfeatures .............................. 59 7.1.1.2 Silviculturalconsiderations ..................... 64 7.1.2 SBSd (Sprucesubzone) .................................... 66 7.1.2.1 Regionalsetting ................................. 66 7.1.2.2 Climate .......................................... 66 7.1.2.3 Vegetation ....................................... 67 7.1.2.4 Soils............................................ 70 7.1.3 SBSe (Subalpine fir subzone) ............................. 71 7.1.3.1 Regionalsetting ................................. 71 7.1.3.2 Climate.......................................... 71 7.1.3.3 Vegetation ....................................... 72 7.1.3.4 Soils............................................ 74 8.0 ECOSYSTEM UNITS OF THESUB-BOREAL SPRUCE ZONE ........................ 75 8.1 Introduction and Definitions .................................... 75 8.1.1General description page ................................. 75 8.1.2 Vegetation page .......................................... 80 8.1.3 Soils page ............................................... 82 8.2 Ecosystem Units of the SBSd: Spruce Subzone .................... 85 SBSd/Ol Mesicrose - peavine - moss ecosystemassociation .... 87 SBSd/Ol(a) Mesicrose - peavine - moss ecosystemassociation: Coarse textured phase ................................ 89 SBSd/Ol(b) Mesic rose - peavine - moss ecosystemassociaton: Finetextured phase .................................. 90 SBSd/Ol Mesicrose - peavine - moss ecosystemassociation: Aspen-dominated seralstages ......................... 96 SBSd/O2 Pine - lichen ecosystem association.................. 97 SBSd/03 Pine - lichen - moss ecosystemassociation ........... 101 SRSd/O4 Saskatoon - wheatgrassscrub/steppe ecosystem association .......................................... 105 SBSd/05 Grassland ecosystems .................................. 110 SBSd/06 Douglas-fir .soopolallie ecosystem association ....... 115 SBSd/07 Submesic bunchberry .moss ecosystemassociation ...... 120 SBSd/08 Moistshrub .forb ecosystem association .............. 125 SBSd/O9 Spruce - horsetail ecosystem association .............. 132 SBSd/09(a) Spruce - horsetail ecosystemassociation: Fluvial phase ................................................. 135 SBSd/09(b) Spruce - horsetail ecosystemassociation: Lacustrine phase ................................................. 136 SBSd/lO Cottonwoodbottomland ecosystem associaton ............ 140 8.2.1Wetlands .................................................. 144 SBSd/ll Swamp ecosystems ...................................... 148 SBSd/12 Bog ecosystems ........................................ 152 8.3 Ecosystem Units of the SBSel: Subalpine Fir Subzone, Western Variant ....................................... 156 SBSel/OlMesic bunchberry - moss ecosystem association ......... 158 SBSel/Ol.lMesic bunchberry - moss: Black huckleberry subassociation ........................................ 161 SBSel/Ol.l(a)Mesic bunchberry .moss, Blackhuckleberry sub- association: Coarse textured phase .................... 162 SBSel/Ol .1( b) Mesic bunchberry - moss, Black huckleberry sub- association: Fine textured phase ...................... 163 SBSel/Ol.lMesic bunchberry - moss, Black huckleberry sub- association: Pine - aspen - forb stages ............... 175 SBSel/Ol.Z Mesicbunchberry - moss: Five-leavedbramble subassociation ........................................ 165 SBSel/Ol.Z(a)Mesic bunchberry - moss, Five-leavedbramble sub- association: Coarse textured phase ................. 167 SBSel/Ol.Z(b)Mesic bunchberry - moss, Five-leavedbramble sub- association:Fine textured phase .................. 169 SBSeU01.2 Mesicbunchberry - moss, Five-leaved bramble sub- association: Aspen - shrub - forb stages .............. 175 SBSel/02 Pine - lichen ecosystem association................... 177 SBSel/03 Pine - moss ecosystem association ..................... 181 SBSe1/03(a) Pine - moss ecosystemassociation: Coarse textured phase .............................................