Full-glacial upland tundra vegetation preserved under tephra

• Main Authors: Victoria G. Goetcheus, Hilary H. Birks
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2001
• Subjects: permafrost; Seward Peninsula; Tundra; Beringia
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.555.5401

The nature of the full-glacial vegetation of Beringia has been the subject of a great deal of investigation and debate. Here we present a reconstruction of an intact example of the full-glacial upland vegetation of part of the northern Seward Peninsula at one point in time. The area was blanketed by more than 1m of tephra ca. 18,000 14C BP (ca. 21,500 cal. BP), and the former land-surface was preserved in the permafrost. The discovery of the land-surface provides a unique opportunity to study a fossil ecosystem preserved in situ. Macrofossils were used to reconstruct the vegetation growing at several sites on the buried land-surface. The macrofossil assemblages indicate a vegetation characterized by graminoids and forbs, with the occasional occurrence of Salix arctica. The vegetation was dominated by Kobresia myosuroides, other sedges (Carex), and grasses, with a "ne-scale mosaic related to snow accumulation and moisture availability. Overall, the vegetation was a closed, dry, herb-rich tundra-grassland with a continuous moss layer, growing on calcareous soil that was continuously supplied with loess. Nutrient renewal by loess deposition was probably responsible for the relatively fertile vegetation, and the occurrence of a continuous mat of acrocarpous mosses. Good physiognomic analogues can be suggested, but no exact modern vegetational analogues have been found, probably because the full-glacial environment and climate with loess deposition do not occur today. ( 2000 Elsevier Science Ltd. All rights reserved. 1. The Beringian background Knowledge of the Beringian environment during the