| 1. |
- Cui, Qiao-Yu, et al.
(författare)
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Evaluating fossil charcoal representation in small peat bogs : Detailed Holocene fire records from southern Sweden
- 2020
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Ingår i: The Holocene. - : Sage Publications. - 0959-6836 .- 1477-0911. ; 30:11, s. 1540-1551
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we assess how representative a single charcoal record from a peat profile in small bogs (1.5-2 ha in area) is for the reconstruction of Holocene fire history. We use high-resolution macrocharcoal (>250 mu m) analysis of continuous series of 2 cm(3)samples from two small bogs in southern Sweden. We compare (1) duplicate charcoal records from the same core, (2) duplicate charcoal records from profiles in the same site (10 m apart), and (3) charcoal records from two sites within the same region (15 km apart). Comparisons are made for charcoal counts and area expressed as accumulation rates. The results suggest that (a) charcoal counts and area are highly correlated in all records; (b) duplicate charcoal records within the same core are very similar, although some charcoal peaks are found in only one of the two records; (c) although long-term trends in fire regimes are similar between duplicate charcoal records from nearby profiles within the same site and between charcoal records from sites within the same region, some individual charcoal peaks/fire events are asynchronous between records. The known historical fires of the town of Vaxjo (1570 and 1612 CE) are recorded at the two study sites, which indicates a macrocharcoal source area of minimum 15 km in diameter. The 2 cm(3)peat samples contained relatively low amounts of macrocharcoal; we therefore recommend to analyse larger samples from small peat bogs with comparable peat accumulation rates. This will improve the reliability of the macrocharcoal record and its interpretation.
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| 2. |
- Lemdahl, Geoffrey, et al.
(författare)
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Eemian and Early Weichselian environments in southern Sweden: a multi-proxy study of till-covered organic deposits from the Småland peneplain.
- 2013
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Ingår i: Journal of Quaternary Science. - : Wiley. - 0267-8179 .- 1099-1417. ; 28:7, s. 705-719
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Tidskriftsartikel (refereegranskat)abstract
- Based on their luminescence and infinite radiocarbon ages, organic deposits beneath till at two sites on the Småland peneplain, southern Sweden (Nybygget and Stora Gäddevik), are concluded to have formed before the Middle Weichselian. Applied palaeoecological methods include analyses of pollen, diatoms, charcoal fragments, macroscopic remains of vascular plants and mosses, and insect remains. Pollen-stratigraphical correlations with previously studied interglacial/interstadial sites in southern Sweden, Denmark and northern Germany suggest that the peat at Nybygget dates from the Brørup interstadial or the final stage of the Eemian interglacial, whereas the lake sediments at Stora Gäddevik probably were emplaced during the middle Eemian. We conclude that the peat was formed in a wetland characterized by both wood swamp and open mire vegetation, and surrounded by semi-open woodlands dominated by pine, birch and hazel. The middle Eemian sequence at the Stora Gäddevik site provides evidence of a moderately nutrient-rich to nutrient-rich lake environment with relatively diverse aquatic vegetation. Regional vegetation, as reconstructed using the REVEALS model, was spruce woodland mixed with pine, alder and birch, but also included more open environments with hazel, oak, grasslands and sedge-dominated wetlands. Water shield (Brasenia schreberi), now extinct in Europe, was identified in the Eemian lake deposits, from both pollen and macroscopic remains.
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| 3. |
- Marchant, Rob, et al.
(författare)
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Drivers and trajectories of land cover change in East Africa : Human and environmental interactions from 6000 years ago to present
- 2018
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Ingår i: Earth-Science Reviews. - : Elsevier. - 0012-8252 .- 1872-6828. ; 178, s. 322-378
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Tidskriftsartikel (refereegranskat)abstract
- East African landscapes today are the result of the cumulative effects of climate and land-use change over millennial timescales. In this review, we compile archaeological and palaeoenvironmental data from East Africa to document land-cover change, and environmental, subsistence and land-use transitions, over the past 6000 years. Throughout East Africa there have been a series of relatively rapid and high-magnitude environmental shifts characterised by changing hydrological budgets during the mid- to late Holocene. For example, pronounced environmental shifts that manifested as a marked change in the rainfall amount or seasonality and subsequent hydrological budget throughout East Africa occurred around 4000, 800 and 300 radiocarbon years before present (yr BP). The past 6000 years have also seen numerous shifts in human interactions with East African ecologies. From the mid-Holocene, land use has both diversified and increased exponentially, this has been associated with the arrival of new subsistence systems, crops, migrants and technologies, all giving rise to a sequence of significant phases of land-cover change. The first large-scale human influences began to occur around 4000 yr BP, associated with the introduction of domesticated livestock and the expansion of pastoral communities. The first widespread and intensive forest clearances were associated with the arrival of iron-using early farming communities around 2500 yr BP, particularly in productive and easily-cleared mid-altitudinal areas. Extensive and pervasive land-cover change has been associated with population growth, immigration and movement of people. The expansion of trading routes between the interior and the coast, starting around 1300 years ago and intensifying in the eighteenth and nineteenth centuries CE, was one such process. These caravan routes possibly acted as conduits for spreading New World crops such as maize (Zea mays), tobacco (Nicotiana spp.) and tomatoes (Solanum lycopersicum), although the processes and timings of their introductions remains poorly documented. The introduction of southeast Asian domesticates, especially banana (Musa spp.), rice (Oryza spp.), taro (Colocasia esculenta), and chicken (Gallus gallus), via transoceanic biological transfers around and across the Indian Ocean, from at least around 1300 yr BP, and potentially significantly earlier, also had profound social and ecological consequences across parts of the region. Through an interdisciplinary synthesis of information and metadatasets, we explore the different drivers and directions of changes in land-cover, and the associated environmental histories and interactions with various cultures, technologies, and subsistence strategies through time and across space in East Africa. This review suggests topics for targeted future research that focus on areas and/or time periods where our understanding of the interactions between people, the environment and land-cover change are most contentious and/or poorly resolved. The review also offers a perspective on how knowledge of regional land-use change can be used to inform and provide perspectives on contemporary issues such as climate and ecosystem change models, conservation strategies, and the achievement of nature-based solutions for development purposes.
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| 4. |
- Olsson, Fredrik, et al.
(författare)
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A continuous record of fire covering the last 10500 calendar years from souther Sweden : The role of climate and human activities
- 2010
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 291, s. 128-141
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Tidskriftsartikel (refereegranskat)abstract
- A high-resolution, continuous 10,500 cal. yrs-long macroscopic charcoal record from a peat and lake sediment deposit at Storasjö, in the hemiboreal vegetation zone of southern Sweden, is presented. This record was compared with the microscopic charcoal record from the same core, and tentatively correlated with the macroscopic and microscopic charcoal records from another site (Stavsåkra), situated 30 km West of Storasjö. The charcoal records are also compared with regional climate proxy records with the aim to separate climate microscopic and macroscopic charcoal records represents local history was obtained from the continuous macroscopic charcoal analysis. A tentative correlation of the charcoal records between the sites indicates that most probably of regional character. Both sites exhibit three major phases of high 7250 BC to ca. 4000 BC, and 3) 750 BC to the 19th century. These three phases are separated by periods with lower or very low from the analysis of the recently developed global charcoal database. Fire appears to have been controlled by climate during the early and middle Holocene and by humans during the late Holocene. Warmer and drier climate during the early and middle Holocene caused frequent and intensive natural was an important disturbance factor in the hemiboreal vegetation zone of Sweden and played an important role in the forest dynamics and characteristics of the — from human-induced fire activity. The results suggest that the major signal of bothfire history. The best record of local firefire episodes of the early and middle Holocene arefire activity 1) 8700–8300 BC, 2)fire activity. This general trend is in good agreement with the pattern emerging for Europefires, which suggests thatfire activity might increase under predicted future climate scenarios. The results also suggest that fireflora and fauna of the region.
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| 5. |
- Sim, Thomas G., et al.
(författare)
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Regional variability in peatland burning at mid-to high-latitudes during the Holocene
- 2023
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Ingår i: Quaternary Science Reviews. - : Elsevier. - 0277-3791 .- 1873-457X. ; 305
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Tidskriftsartikel (refereegranskat)abstract
- Northern peatlands store globally-important amounts of carbon in the form of partly decomposed plant detritus. Drying associated with climate and land-use change may lead to increased fire frequency and severity in peatlands and the rapid loss of carbon to the atmosphere. However, our understanding of the patterns and drivers of peatland burning on an appropriate decadal to millennial timescale relies heavily on individual site-based reconstructions. For the first time, we synthesise peatland macrocharcoal re-cords from across North America, Europe, and Patagonia to reveal regional variation in peatland burning during the Holocene. We used an existing database of proximal sedimentary charcoal to represent regional burning trends in the wider landscape for each region. Long-term trends in peatland burning appear to be largely climate driven, with human activities likely having an increasing influence in the late Holocene. Warmer conditions during the Holocene Thermal Maximum (similar to 9e6 cal. ka BP) were associated with greater peatland burning in North America's Atlantic coast, southern Scandinavia and the Baltics, and Patagonia. Since the Little Ice Age, peatland burning has declined across North America and in some areas of Europe. This decline is mirrored by a decrease in wider landscape burning in some, but not all sub-regions, linked to fire-suppression policies, and landscape fragmentation caused by agricultural expansion. Peatlands demonstrate lower susceptibility to burning than the wider landscape in several instances, probably because of autogenic processes that maintain high levels of near-surface wetness even during drought. Nonetheless, widespread drying and degradation of peatlands, particularly in Europe, has likely increased their vulnerability to burning in recent centuries. Consequently, peatland restoration efforts are important to mitigate the risk of peatland fire under a changing climate. Finally, we make recommendations for future research to improve our understanding of the controls on peatland fires.(c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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