A 130 0-year history of vegetation and environmental change at Jan Lake, east-central Alaska

• Published in: The Holocene
• Main Authors: Carlsonl, Lisa J., Finney, Bruce P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: SAGE Publications 2004
• Subjects: Yukon; Tundra; Alaska
• Online Access: http://dx.doi.org/10.1191/0959683604hl762rp; http://journals.sagepub.com/doi/pdf/10.1191/0959683604hl762rp

Pollen, stomates and macrofossils were analysed from a 3.63 m sediment core at Jan Lake, eastcentral Alaska, in order to improve spatial resolution of patterns of vegetation history in this region. The chronology was based on 19 AMS 14 C dates on plant macrofossils and concentrated pollen. Zone Jan-I (12400-11 600 yr BP) records a unique herb-tundra pollen assemblage, particularly high in Chenopodia ceae, adding supporting evidence for a spatial mosaic of lateglacial vegetation in east-central Alaska. Unexpected pollen of Picea, Betula and Alnus in lateglacial sediments appears to arise from reworking of older pollen-bearing deposits, according to a radiocarbon date of 22180yr BP on a pollen sample. Shrub Betula tundra dominates zone Jan-Il (11 600-10000 yr BP), with indications of climatic amelioration. Tree species (Populus, Picea glauca, Betula papyrifera) began to arrive in zone Jan-Illa (9200-6600 yr BP), and the modern boreal forest, including Alnus and Picea mariana, became established during zone Jan-IIlb (6600-0 yr BP). Fossil stomates appear to be an effective indicator of initial local occurrence of Picea at Jan Lake. Picea arrival at Jan Lake is within 300 years of its arrival at other AMS-dated sites across eastern and central Alaska. A migration route into Alaska through the drainages of the Tanana or Yukon Rivers is hypothesized. Evidence is found for a slight mid-Holocene Picea decline at Jan Lake, intermediate in magnitude between Picea pollen records showing no decline to the east and a larger decline to the west in Alaska.