ausblenden:
Schlagwörter:
Pollen data
Plant functional types
Biomes
Vegetation changes
Climate changes
Alaska
Eastern siberia
Mid-holocene
Last glacial maximum
Late-quaternary vegetation
Mackenzie river basin
Northwestern alaska
Climate-change
Postglacial vegetation
Northeastern alaska
Model simulations
Northern yukon
Late wisconsin
Brooks range
Zusammenfassung:
The objective biomization method developed by Prentice ef al. (1996) for Europe was extended using modern pollen samples from Beringia and then applied to fossil pollen data to reconstruct palaeovegetation patterns at 6000 and 18,000 C-14 yr sp. The predicted modern distribution of tundra, taiga and cool conifer forests in Alaska and north-western Canada generally corresponds well to actual vegetation patterns, although sites in regions characterized today by a mosaic of forest and tundra vegetation tend to be preferentially assigned to tundra. Siberian larch forests are delimited less well, probably due to the extreme under-representation of Larix in pollen spectra. The biome distribution across Beringia at 6000 C-14 yr sp was broadly similar to today, with little change in the northern forest limit, except for a possible northward advance in the Mackenzie delta region. The western forest limit in Alaska was probably east of its modern position. At 18,000 C-14 yr sr the whole of Beringia was covered by tundra. However; the importance of the various plant functional types varied from site to site, supporting the idea that the vegetation cover was a mosaic of different tundra types. [References: 141]
