Relict permafrost preserves megafauna, insects, pollen, soils and pore- ice isotopes of the mammoth steppe and its collapse in central Yukon
Back to previous page
| Authors: | Monteath, AJ; Kuzmina, S; Mahony, M; Calmels, F; Porter, T; Mathewes, R; Sanborn, P; Zazula, G; Shapiro, B; Murchie, TJ; Poinar, HN; Sadoway, T; Hall, E; Hewitson, S; Froese, D |
| Year: | 2023 |
| Journal: | Quat. Sci. Rev. 299 Article Link (DOI) |
| Title: | Relict permafrost preserves megafauna, insects, pollen, soils and pore- ice isotopes of the mammoth steppe and its collapse in central Yukon |
| Abstract: | In eastern Beringia (unglaciated Alaska and western Yukon), the Pleistocene-Holocene transition was characterised by rapid changes in plant, insect and mammal communities as the mammoth steppe ecosystem was replaced, first by shrub tundra and later boreal forest. These changes indicate a transition from well drained terrain with deep active layers to wetter, cooler soils, to which steppe-tundra vege-tation was poorly adapted. The nature and precise timing of these events is not well resolved, particularly in central Yukon where regional climate may have been strongly affected by the retreating Cordilleran-Laurentide ice sheet complex. Resolving this uncertainty is not only important for understanding past ecosystems, but also provides a long-term perspective for contemporary environmental change and shrub expansion that affects large areas of northern high-latitudes today. Here, we report chronology (41 radiocarbon dates), stratigraphy, pore-ice d2H/d18O measurements, pollen data, megafauna remains and fossil insect assemblages from a permafrost-preserved loessal sequence in central Yukon, named Lucky Lady. The site spans the interval from ca. 17,000 to 8000 cal yr BP (calibrated years before C.E. 1950) and records the Pleistocene-Holocene transition in exceptional resolution. Full glacial environments (ca. 16,500 cal yr BP) supported elements of steppe-tundra vegetation and an insect fauna dominated by Connatichela artemisiae -an endemic weevil indicating warm soil temperatures. The collapse of the mammoth steppe ecosystem began with slowing of loess accumulation and development of paleosol ca. 13,480 cal yr BP. At this time, C. artemisiae remains become infrequent and Artemisia pollen decline to be replaced by Cyperaceae (ca. 13,220), before mesic, shrub taxa (likely dwarf Betula and Salix) becomes dominant ca. 13,210 cal yr BP. The establishment of shrub tundra is associated with rapid changes in d2H/ d18O measurements, suggesting that ecological turnover coincided with a shift in atmospheric conditions and moisture availability. Finally, boreal vegetation communities became established ca. 10,680 cal yr BP. The replacement of steppe-tundra vegetation in central Yukon lagged other areas of eastern Beringia by as much as 1000 years and coincided with rapid deglaciation during the Bolling-Allerod time-period (14,600-12,90 0 cal yr BP). Turnover in insect and vegetation communities took place in ca. 40 years as shrub tundra became dominant. This rapid turnover has parallels with contemporary Arctic greening and re-emphasises the sensitivity of high-latitude environments to climate change.(c) 2022 Elsevier Ltd. All rights reserved. |
Please send suggestions for improving this publication database to
sass-support@sfu.ca.
Departmental members may update their publication list.