Reexamination of Postglacial Vegetation History in Northern Idaho: Hager Pond, Bonner Co.

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Abstract
Hager Pond, a mire in northern Idaho, reveals at least five pollen zones since sediments formed after the last recession of continental ice (>9500 yr BP). Zone I (>9500-8300 yr BP) consists mainly of diploxylon pine, plus low percentages ofAbies, Artemisia, andPicea. SEM examination of conifer pollen at selected levels in the zone reveals thatPinus albicaulis, P. monticola, andP. contortaare present in unknown proportions. The zone resembles modern pollen spectra from theAbies lasiocarpa-P. albicaulisassociation found locally today only at high elevation. Presence of whitebark pine indicates a cooler, moister climate than at present, but one which was rapidly replaced in Zone II (8300-7600 yr BP) by warmer, drier conditions as inferred by prominence of grass with diploxylon pine. Zone III (7600-3000 yr BP) was probably dominated byPseudotsuga menziesii, plus diploxylon pine and prominentArtemisiaand denotes a change in vegetation but continuation of the warmer drier conditions. Beginning at approximately 3000 yr BPPicea engelmannii, Abies lasiocarpa, and/orA. grandisand diploxylon pine were dominants and the inferred climate became cooler and moister concomitant with Neoglaciation. The modern climatic climax (Zone 157), withTsuga heterophyllaas dominant, has emerged in approximately the last 1500 yr.