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A palaeoecological study was performed in the northern Scandinavian mountain range in Sweden. The aim was to study vegetation changes and shifts in forest limit altitudes during the last 5000 years in a tree-less archaeological site (Adamvalta) situated below the regional forest limit, and in a forested reference area with similar geological features but without archaeological evidence of human presence (Ajdevaratj). The suitability of uncritically using forest limit changes as indicators of climate change is also discussed. The study included analyses of pollen, pollen accumulation rates (PAR), macrofossils and loss-on-ignition. The results indicate vegetation changes in both areas plausibly caused by climate c. 3800 BP and c. 500–400 BP. However, at Adamvalta, settlements were established c. 1300–750 BP, close to the mountain birch (Betula pubescens ssp. czerepanovi) forest limit. About 800 BP, the birch forest cover at Adamvalta decreased and the vegetation developed into an alpine heath, as a result of human-induced deforestation. The following ‘Little Ice Age’, in combination with human impact from the sixteenth century onwards, prevented forest recovery, and the site remains treeless. Such vegetation changes were not recorded at Adjevaratj. It is deduced that the present position of the forest limit at Adamvalta is governed by a combination of factors where previous human impact and climate have been the major driving forces determining the long-term vegetation development. Hence, a thorough knowledge of the site history is important when forest limits are used as a proxy for climate change. [ABSTRACT FROM AUTHOR]

Based on lacustrine and morpho-stratigraphical evidence from Lyngen in Troms, northern Norway, 13 marginal moraines have been mapped in front of Lenangsbreene in Strupskardet. Moraines M1 – M13 are inferred to represent glacier halts or advance/readvance taking place during the Lateglacial and Holocene. The presence of collapse depressions suggests that some of them were ice cored (M1 – M3). A chronological framework, taking into account a combination of former shorelines and related glacier-meltwater channels, lichenometry and AMS radiocarbon-dated lacustrine sediments spanning the last 20 000 cal. yr BP, has been established. The distal glacier-fed lake Aspvatnet was isolated from the seac. 10 300 cal. yr BP, and the lacustrine sediments have been investigated by use of loss-on-ignition (LOI) magnetic susceptibility, water content, wet and dry bulk density (DBD), and the magnetic parameters anhysteretic remanent magnetization (ARM) and saturation remanent magnetization (SIRM). There is, in general, good agreement between physical sediment parameters and magnetic parameters. DBD, a combination of medium and fine silt and the two statistical parameters 'sorting' and 'mean' have been used to construct a high-resolution glacier-fluctuation curve for the last 3800 cal. yr BP. Based on an accumulation-area ratio (AAR) of 0.6 and an ablation-accumulation balance ratio (ABR) approach, a continuous temperature–precipitation–wind equilibrium-line altitude (TPW-ELA) curve for the last 20 000 cal. yr BP has been constructed. Using an established exponential relationship between mean ablation-season temperature and mean annual solid precipitation at the ELA of Norwegian glaciers, variations in mean winter precipitation (snow) are quantified using an independent proxy for summer temperature. Mean annual winter precipitation varied from 500 to 5000 mm water equivalent, and on average, Holocene estimates are c. 50% higher than similar figures from the Lateglacial. The two driest periods occurred during Heinrich events 1 (H1) (17 500–16 500) and 0 (H0) (13 000–12 200), whereas freshwater pulses to the North Atlantic had apparently no systematic impact on mean winter precipitation. Based on the winter precipitation curve from Lyngen, the atmospheric circulation responded to the sea surface temperature (SST) lowering associated with H1 and H0. The dry and cold climate during the events led to formation of talus-derived rock glaciers at sea level. [ABSTRACT FROM AUTHOR]