| 1. |
- Hörnberg, Greger, et al.
(författare)
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Fire as an important factor for the genesis of boreal Picea abies swamp forests in Fennoscandia
- 2012
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 22:2, s. 203-214
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Tidskriftsartikel (refereegranskat)abstract
- The initial establishment of Picea abies in Sweden and Norway on a landscape level, between 3000 and 1000 years ago, was often preceded by recurrent fire and thereafter the influence of fire decreased. However, in some swamp forests, the absence of fire over the last 3500 years has promoted the continuous presence of deciduous trees, i.e. Picea has not established although it has been present regionally for over 3000 years. Our objective was to study long-term vegetation development and fire history in a Picea swamp forest located close (c. 600 m) to a deciduous swamp forest with a documented fire-free history in northernmost Sweden. The study included analyses of charred particles, pollen and ignition residues. Principal component analysis was applied to identify major changes in the pollen spectra. Our results showed that the current Picea swamp forest has developed from a deciduous fen and that fires affected the fen between 6700 and 2300 cal. yr BP. Picea abies established on the fen around 2200 cal. yr BP, following the last local on-site fire. The main factors responsible for the local vegetation development have been: fire (6700 to 2300 cal. yr BP); autogenous processes and climate (2300 to 1000 cal. yr BP); autogenous processes or anthropogenic impact (1000 to 300 cal. yr BP); anthropogenic impact through selective cutting and grazing (300 to 100 cal. yr BP); and autogenous processes and grazing (100 cal. yr BP to present). We conclude that fire facilitated the initial Picea abies establishment. Once established, Picea abies created local conditions that in combination with a colder and wetter climate prevented fire and the establishment of other tree species.
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| 2. |
- Staland, Hanna, et al.
(författare)
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A thousand years of human impact in the northern Scandinavian mountain range: Long-lasting effects on forest lines and vegetation
- 2011
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Ingår i: Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 21, s. 379-391
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Tidskriftsartikel (refereegranskat)abstract
- The vegetation history has been examined by pollen, microscopic and macroscopic charcoal analyses in the vicinity of two alpine Stallo settlement sites and one forested 'Reference area' with no settlement remains in northwestern Sweden in the northern part of the Scandinavian mountain range. The acquired data provide indications of the effects of human activities on local vegetation during the settlement phase, and on ecological processes in both long-and short-term perspectives. The results show that one settlement site, Gieddealge, was established just above the forest line in the Betula treeline zone, and the other, Varenodjukke, in the Betula forest. At Gieddealge an increase in herbs and graminoids appears to have occurred c. 700 cal. BP (during the thirteenth century) suggesting that the vegetation was altered by nutrient addition, most likely related to human activities associated with the settlement. At Varenodjukke, the Betula trees around the settlement were cut down and the site developed into an alpine heath dominated by Betula nana, which still characterizes the site today. In the Reference area evidence of changes to the vegetation probably caused by human impact was also found from c. 3500 to 700 cal. BP. In conclusion, the vegetation currently present at Gieddealge and Varenodjukke has been strongly influenced by previous human activities, which have clearly had profound effects, both short and long term, on the composition of the vegetation and the properties of the ecosystems in these areas. Further, when studying processes, such as anticipated global warming that will influence future patterns of vegetation in these forest-line areas, legacies of land use must be taken into consideration.
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| 3. |
- Staland, Hanna, et al.
(författare)
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The history of a farm-shieling system in the central Swedish forest region
- 2010
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Ingår i: Vegetation History and Archaeobotany. - : Springer Science and Business Media LLC. - 0939-6314 .- 1617-6278. ; 19, s. 103-119
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Tidskriftsartikel (refereegranskat)abstract
- The local vegetation history of three sites in the forested region of central Sweden was studied. These sites were the forest village site A"ngersjo and the two nearby shieling sites, Gammelvallen and A-jingsvallen. The aim of the study was to elucidate the relationship between the establishment of the farm and of the shielings. The results indicate that agriculture began in the area in the Roman Iron Age or Migration period. There is evidence of contemporaneous human activity in the village of A"ngersjo and the shieling at A-jingsvallen, suggesting the development of a farm-shieling system. We suggest that permanent farms and shielings were established concurrently as a local system, and that one of the main reasons was to demonstrate that the territory between the farm and the shieling was a potential resource area belonging to the farm. The problems of using pollen to differentiate between a shieling and a farm are also evaluated and it is concluded that multiple sites as well as a multidisciplinary approach is essential in order to be able to address such complex problems as the emergence of the farm-shieling system.
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| 4. |
- Staland, Hanna, et al.
(författare)
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Vegetation development at a mountain settlement site in the Swedish Scandes during the late Holocene: palaeoecological evidence of human-induced deforestation
- 2009
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Ingår i: Vegetation History and Archaeobotany. - : Springer Science and Business Media LLC. - 0939-6314 .- 1617-6278. ; 18, s. 297-314
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Tidskriftsartikel (refereegranskat)abstract
- A palaeoecological study was conducted close to the forest limit in the northern Scandinavian mountain range. The aim was to elucidate the degree to which human impact has affected the vegetation at Hiednikvalta, a Stallo settlement site. Stallo settlements consist of round hut foundations that have a hearth in the middle and are surrounded by a low turf wall. They were probably established by Sami people using the mountain areas for hunting and/or reindeer herding. In order to separate the effects of humans and climate on the vegetation, a reference area approach was adopted, i.e. the vegetation development at the Stallo settlement site Hiednikvalta was compared with the vegetation development in a forested reference area AvvuhatjAyenhkkAyen, at the same altitude as Hiednikvalta but with no archaeological remains of settlements. Peat stratigraphies were retrieved at the two sites and pollen analysis, loss-on-ignition (LOI), pollen accumulation rates (PAR), macrofossil analysis and Betula pollen size statistics were all examined. The results indicate that Hiednikvalta was forested with Betula trees prior to the Stallo settlement period, which occurred between the eighth and thirteenth centuries. Human activities resulted in a decrease in tree cover at the site, as found in a previous study at Adamvalta, another Stallo settlement site in the region. However, the magnitude of vegetation change, and the post-Stallo vegetation development differed between the two areas, suggesting that site-specific factors are important. The use of reference areas in palynological studies is also discussed.
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