High-resolution Holocene vegetation history and climate from Hole 1034B, ODP leg 169S, Saanich Inlet, Canada

High-resolution pollen analysis of laminated marine sediments from ODP Hole 1034B in Saanich Inlet, British Columbia reveals changes in vegetation and inferred climate during the Holocene, Four main pollen zones are discerned using constrained cluster analysis. Although the timing of major vegetatio n changes at the Saanich Inlet is similar to other study sites in the Pacif ic Northwest, the composition of pollen assemblage zones is different from the mainland sites. Vegetation assemblages reconstructed from the pollen an d spore record include a Douglas-fir (Pseudotsuga menziesii) parkland with abundant grass (Poaceae) and bracken (Pteridium) between 11,450 and 8300 BP (all ages are calibrated calendar years), oak (Quercus) savanna or parklan d with high grass and bracken (8300-7040 BP), a mixed deciduous/coniferous forest with oak, western hemlock (Tsuga heterophylla) and Douglas-fir (7040 -5750 BP), and the development of modem coastal temperate forest with the m arked expansion of cedar (Cupressaceae), western hemlock, spruce (Picea) an d Douglas-fir (5750-1050 BP). Climatic periods inferred from the cores incl ude an early Holocene warm/dry interval (11,450-8300 BP), a warm period wit h mild winters (8300-7040 BP), a period of transitional mid-Holocene climat e (7040-5750 BP), and the advent of a relatively cool/ wet neoglacial clima te after 5750 BP, Modern conifer forests and oak savannas became establishe d by about 3800 BP. The Saanich Inlet pollen record indicates that vegetati on and inferred climate change was particularly rapid between 8700 and 8300 BP when grass and bracken abruptly decrease and oak becomes a significant component of the paleovegetation. Because neoglacial conditions have prevai led from 3800 years to present in the Pacific Northwest, factors other than climate, such as anthropogenic modification of the landscape, may be respo nsible for the persistence of oak savannas. (C) 2001 Elsevier Science B.V. All rights reserved.