British Columbia Vegetation and Climate History with Focus on 6 ka BP

Abstract

British Columbia Holocene vegetation and climate is reconstructed from pollen records. A coastal Pinus contorta paleobiome developed after glacier retreat under cool and probably dry climate. Cool moist forests involving Picea, Abies, Tsuga spp., and Pinus followed until the early Holocene. Pseudotsuga menziesii arrived and spread in the south 10 000-9000 BP, and Picea sitchensis - Tsuga heterophylla forests developed in the north. T. heterophylla increased 7500-7000 BP, and Cupressaceae expanded 5000-4000 BP. Bogs began to develop and expland. Modern vegetation arose 4000-2000 BP. There were early Holocene grass and Artemisia communities at mid-elevations and pine stands at high elevations in southern interior B.C. Forests expanded downslope and lakes formed 8500-7000 BP. Modern forests arose 4500-4000 BP while lower and upper tree lines declined. In northern B.C. non-arboreal communities preceded middle Holocene Picea forests. Abies, Pinus and Picea mariana predominated at various sites after 4000 BP. At 6000 BP Tsuga heterophylla (south) and Picea sitchensis (north) dominated the coast and islands and Quercus garryana and Pseudotsuga on southeast Vancouver Island, but Thuja plicata was infrequent. Southern Interior Plateau vegetation at 6000 BP was more open than today at middle to lower elevations, whereas forests covered the Northern Interior Plateau. Picea forests occurred in northern B.C. Holocene climate phases were: 1) warm dry "xerothermic" ca. 9500-7000 BP, 2) warm moist "mesothermic" ca. 7000-4500 BP, 3) moderate and moist 4500-0 BP, with increasing moisture 8500-6000 BP and cooling (?increased moisture) 4500-3000 BP. B.Cs Hypsithermal had dry and wet stages; 6000 BP occurred in the warm and wet mesothermic stage.Cette reconstitution a été effectuée à partir des données polliniques. Un paléobiome à Pinus contorta s'est établi après le retrait des glaciers sous un climat frais et probablement sec. Des forêts de climat frais et humide à dominance de Picea, Abies, Tsuga spp. et Pinus ont suivi, jusqu'à l'Holocène inférieur. Pseudotsuga menziesii s'est ensuite répandu dans le sud de 10 000 à 9000 BP, tandis que les forêts à Picea sitchensis - Tsuga heterophylla se sont répandues dans le nord. T. heterophylla s'est accru de 7500 à 7000 BP et Cupressaceae s'est répandu de 5000 à 4000 BP. La végétation moderne s'est manifestée de 4000-2000 BP. Dans le sud de la partie intérieure, il y a eu des herbes et des communautés d'Artemisia aux altitudes moyennes et des peuplements de pins en haute altitude au début de l'Holocène. Les forêts modernes se sont formées de 4500 à 4000 BP, tandis que les limites des arbres déclinaient. Au nord, les communautés non arboréennes ont précédé les forêts de pins de l'Holocène moyen. Abies, Pinus et Picea mariana ont prédominé en différents sites après 4000 BP. À 6000 BP, Tsuga heterophylla (au sud) et Pinus sitchensis (au nord) ont dominé sur les côtes et les îles et Quercus garryana ainsi que Pseudotsuga, le sud-est de l'île de Vancouver. La végétation du sud du plateau intérie...

Postglacial vegetation and climate dynamics in the Seymour‐Belize Inlet Complex, central coastal British Columbia, Canada: palynological evidence from Tiny Lake

“…Climate models, pollen transfer functions and palaeoecological data document a period of maximum temperatures and minimum precipitation in western Washington and south coastal BC centred at ca. 8000 a BP (Mathewes, 1973;Barnosky, 1981;Leopold et al, 1982;Hebda, 1983;Hebda and Mathewes, 1984;Heusser et al, 1985;Kutzbach and Guetter, 1986;McLachlan and Brubaker, 1995;Hebda, 1995;Hebda, 2002, 2003;Lacourse, 2005). Instead, early Holocene climate change at Tiny Lake and Two Frog Lake is contemporaneous with sites in southwestern Yukon, coastal Alaska and some locations in northern BC (Fig.…”

Environmental change in Garry oak (Quercus garryana) ecosystems: the evolution of an eco-cultural landscape

“…The Holocene climate along south coastal British Columbia has varied considerably over the last 12,000 years (Mathewes 1985;Hebda 1995;Walker and Pellatt 2003). After deglaciation, warm dry conditions occurred on southeastern Vancouver Island (11,450-8,300 BP) and were typical of climate throughout the coast of BC at the time (Walker and Pellatt 2003), with frequent fires also occurring in the Fraser Valley (Mathewes 1973).…”

Post-glacial diatom-inferred aquatic changes in Sicamous Creek Lake, British Columbia, Canada

“…Their occurrence at 270-220 cm (6,500-5,000 14 C yr BP) falls within the moist and warm mesothermic period (7,(0)(1)(2)(3)500 14 C yr BP) identified by HEBDA (1995HEBDA ( , 2007. HICKMAN and REASONER (1994) found comparable abundances of one planktonic Cyclotella taxon at a similar time period (10,000 until 5,000 cal.…”

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