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- Gaillard, Marie-José, 1953-, et al.
(författare)
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Holocene land-cover reconstructions for studies on land cover-climate feedbacks
- 2010
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 6, s. 483-499
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Tidskriftsartikel (refereegranskat)abstract
- The major objectives of this paper are: (1) to review the pros and cons of the scenarios of past anthropogenic land cover change (ALCC) developed during the last ten years, (2) to discuss issues related to pollen-based reconstruction of the past land-cover and introduce a new method, REVEALS (Regional Estimates of VEgetation Abundance from Large Sites), to infer long-term records of past land-cover from pollen data, (3) to present a new project (LANDCLIM: LAND cover – CLIMate interactions in NW Europe during the Holocene) currently underway, and show preliminary results of REVEALS reconstructions of the regional land-cover in the Czech Republic for five selected time windows of the Holocene, and (4) to discuss the implications and future directions in climate and vegetation/land-cover modeling, and in the assessment of the effects of human-induced changes in land-cover on the regional climate through altered feedbacks. The existing ALCC scenarios show large discrepancies between them, and few cover time periods older than AD 800. When these scenarios are used to assess the impact of human land-use on climate, contrasting results are obtained. It emphasizes the need for methods such as the REVEALS model-based land-cover reconstructions. They might help to fine-tune descriptions of past land-cover and lead to a better understanding of how long-term changes in ALCC might have influenced climate. The REVEALS model is demonstrated to provide better estimates of the regional vegetation/landcover changes than the traditional use of pollen percentages. This will achieve a robust assessment of land cover at regional- to continental-spatial scale throughout the Holocene. We present maps of REVEALS estimates for the percentage cover of 10 plant functional types (PFTs) at 200 BP and 6000 BP, and of the two open-land PFTs “grassland” and “agricultural land” at five time-windows from 6000 BP to recent time. The LANDCLIM results are expected to provide crucial data to reassess ALCC estimates for a better understanding of the land suface-atmosphere interactions.
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| 2. |
- Möller, Per, et al.
(författare)
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Living at the margin of the retreating Fennoscandian ice sheet : the early mesolithic sites at Aareavaara, northernmost Sweden
- 2013
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 23:1, s. 104-116
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Tidskriftsartikel (refereegranskat)abstract
- During an archaeological survey in Pajala parish, northernmost Sweden, clusters of quartz waste from knapping and burnt bone were discovered on a glaciofluvial gravel plateau close to Aareavaara village in the Muonio River valley. Sampled materials from a larger area and small-scale excavations (in total 6 m2) are interpreted as resulting from short-stay hunter-gatherer camps. Radiocarbon dating on burnt bones suggest an age of occupancy at ~10,700 cal. yr BP, which is more or less contemporary with ‘Komsa Phase’ sites on the north coast of Norway (~300–360 km northwards). The Aareavaara site should thus be the oldest known archaeological site to date in northern Sweden. A palaeoenvironmental reconstruction, based on pollen analysis of sediment cores from two nearby lakes and radiocarbon dating of macrofossils for construction of time/depth sedimentation curves, suggests a deglaciation age of the area corresponding to occupation by early man (~10,700 cal. yr BP). Aareavaara was at the time of deglaciation situated in a transitional zone between subaqueous and subaerial ice-margin retreat from the northeast towards the southwest, with higher hills and plateaux forming an archipelago in the Ancylus Lake with highest shorelines formed at ~170 m a.s.l. The hunter-gatherer camp sites at Aareavaara were thus, both in time and space, located in close proximity to the retreating ice sheet margin, but also in a waterfront location, in fact on an island in the Ancylus Lake. Our pollen data suggest a subarctic birch woodland tundra landscape characterized by open vegetation, including occasional birch trees and an abundance of willow and dwarf birch.
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