| 1. |
- Adolf, Carole, et al.
(author)
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The sedimentary and remote-sensing reflection of biomass burning in Europe
- 2018
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In: Global Ecology and Biogeography. - : WILEY. - 1466-822X .- 1466-8238. ; 27:2, s. 199-212
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Journal article (peer-reviewed)abstract
- Aim: We provide the first European-scale geospatial training set relating the charcoal signal in surface lake sediments to fire parameters (number, intensity and area) recorded by satellite moderate resolution imaging spectroradiometer (MODIS) sensors. Our calibration is intended for quantitative reconstructions of key fire-regime parameters by using sediment sequences of microscopic (MIC from pollen slides, particles 10-500 mu m) and macroscopic charcoal (MAC from sieves, particles > 100 mu m). Location: North-south and east-west transects across Europe, covering the mediterranean, temperate, alpine, boreal and steppe biomes. Time period: Lake sediments and MODIS active fire and burned area products were collected for the years 2012-2015. Methods: Cylinder sediment traps were installed in lakes to annually collect charcoal particles in sediments. We quantitatively assessed the relationships between MIC and MAC influx (particles/cm(2)/year) and the MODIS-derived products to identify source areas of charcoal and the extent to which lake-sediment charcoal is linked to fire parameters across the continent. Results: Source area of sedimentary charcoal was estimated to a 40-km radius around sites for both MIC and MAC particles. Fires occurred in grasslands and in forests, with grass morphotypes of MAC accurately reflecting the burned fuel-type. Despite the lack of local fires around the sites, MAC influx levels reached those reported for local fires. Both MIC and MAC showed strong and highly significant relationships with the MODIS-derived fire parameters, as well as with climatic variation along a latitudinal temperature gradient. Main conclusions: MIC and MAC are suited to quantitatively reconstructing fire number and fire intensity on a regional scale. However, burned area may only be estimated using MAC. Local fires may be identified by using several lines of evidence, e.g. analysis of large particles (> 600 mu m), magnetic susceptibility and sedimentological data. Our results offer new insights and applications to quantitatively reconstruct fires and to interpret available sedimentary charcoal records.
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| 2. |
- Cui, Qiao-Yu, et al.
(author)
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Evaluating fossil charcoal representation in small peat bogs : Detailed Holocene fire records from southern Sweden
- 2020
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In: The Holocene. - : Sage Publications. - 0959-6836 .- 1477-0911. ; 30:11, s. 1540-1551
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Journal article (peer-reviewed)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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| 3. |
- Cui, Qiao-Yu
(author)
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Fire history in the hemiboreal and southern boreal zones of southern Sweden during 11000 years : Relationships with past vegetation composition and human activities and implications for biodiversity issues
- 2013
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Doctoral thesis (other academic/artistic)abstract
- This thesis studies fire history over the last 11 000 years (Holocene) in central Småland, southern Sweden, on the basis of palaeoecological analyses of peat sequences from three small bogs (Notteryd, Stavsåkra and Storasjö). The main objective is to gain insights into the long-term relationships between fire, climate, human-impact, other environmental factors and the history of biodiversity in the study region. The following hypotheses are tested: 1) there are no between-site differences in i) Holocene fire history, ii) abundance of deciduous trees versus pine and forest openness over the Holocene, and iii) landscape history over the last three centuries, and 2) there are no within-site differences in the Holocene charcoal records.Hypothesis 1 (i-iii) is tested using all charcoal records (three sites) and pollen-based Landscape Reconstruction Algorithm (LRA) estimates of past percentage cover of plant taxa and land-use/vegetation units over the last three centuries (test of the LRA using historical maps), and the entire Holocene. Hypothesis 2 is tested using two parallel charcoal records from the same core at Notteryd. The charcoal data comprise continuous records of macroscopic charcoal (macro-C), microscopic charcoal records from pollen slides, and identification of charcoal fragments to plant taxa. Chronologies are based on series of 14C dates from terrestrial plant remains and age-depth models achieved using Bayesian statistics.Accumulation rates (AR) of the area of macro-C was found to be better to use than AR of the number of macro-C for interpretation of the results. Within-site differences in charcoal records exist and have to be considered. Besides climate, forest tree-composition (related to geomorphological settings) was shown to play a primordial role in Early and Mid-Holocene fire history, while land-use was a major factor in the Late Holocene. Three different histories of forest development and land-use changes within the same region are revealed, implying a multitude of landscape types over time and space. These long-term landscape histories were at the origin of the high biodiversity still existing in the 18th century. Major landscape transformations due to agrarian reforms since the 18th century resulted in a dramatic loss of landscape and species biodiversity over the last two centuries.
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| 4. |
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| 5. |
- Molinari, Chiara, et al.
(author)
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Exploring potential drivers of European biomass burning over the Holocene: a data-model analysis
- 2013
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In: Global Ecology and Biogeography. - : Wiley. - 1466-8238 .- 1466-822X. ; 22:12, s. 1248-1260
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Journal article (peer-reviewed)abstract
- AimTo reconstruct spatial and temporal patterns of European fire activity during the Holocene and to explore their potential drivers, by relating biomass burning to simulated biotic and abiotic parameters. LocationEurope. MethodsHolocene fire activity was investigated based on 156 sedimentary charcoal records from lakes and peat bogs across Europe. Charcoal data covering the last 9000 years were statistically compared with palaeoclimate data derived from the Max Planck Institute for Meteorology/University of Wisconsin-Madison Earth System Model, with vegetation and fire indices simulated with the dynamic vegetation model lpj-guess and with two independent scenarios of past anthropogenic land-cover change. ResultsThe combined sedimentary charcoal records suggest that there was little fire activity during the early and the middle Holocene compared with recent millennia. A progressive increase in fire frequency began around 3500cal. yr bp and continues into the late Holocene. Biomass burning rose sharply from 250cal. yr bp onwards, reaching a maximum during the early Industrial Era and then declining abruptly. When considering the whole Holocene, the long-term control of fire is best explained by anthropogenic land-cover change, litter availability and temperature-related parameters. Main conclusionsWhile the general patterns found across Europe suggest the primary role of vegetation, precipitation and temperature-related parameters in explaining fire dynamics during the early Holocene, the increase in fire activity observed in the mid-late Holocene is mainly related to anthropogenic land-cover changes, followed by vegetation and temperature-related parameters. The 20th-century decline in biomass burning seems to be due to increased landscape fragmentation and active fire suppression policies. Our hypothesis that human activities played a primary role in Holocene biomass burning across Europe could be tested by improved palaeoclimate reconstructions and more refined representations of anthropogenic fires in climate and vegetation models.
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| 6. |
- Vannière, Boris, et al.
(author)
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7000-year human legacy of elevation-dependent European fire regimes
- 2016
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In: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 132, s. 206-212
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Journal article (peer-reviewed)abstract
- Variability in fire regime at the continental scale has primarily been attributed to climate change, often overshadowing the widely potential impact of human activities. However, human ignition modifies the rhythm of fire episodes occurrence (fire frequency), whereas land use alters vegetation composition and fuel load, and thus the amount of biomass burned. It is unclear, however, whether and how humans have exercised a significant influence over fire regimes at continental and millennial scales. Based on sedimentary charcoal records, we use new alternative estimate of fire frequency and biomass burned for the last 16000 years (here after 16 ky) that we evaluate with outputs from climate, vegetation, land use and population models. We find that pronounced regional-scale land use changes in southern Europe at the beginning of the Neolithic (8-6 ky), during the Bronze Age (5-4 ky) and the medieval period (1 ky) caused a doubling of fire frequency compared to the Holocene average (the last 11.5 ky). Despite anthropogenic influences, southern European biomass burned decreased from 7 ky, which is in line both with changes in orbital parameters leading climate cooling and also reductions in biomass availability because of land use. Our study underscores the role of elevation-dependent parameters, and particularly biomass and land management, as major drivers of fire regime variability. Results attest a determinant anthropogenic driving-force on fire regime and a decrease in fire-carbon emissions since 7 ky in Southern Europe.
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| 7. |
- Walsh, Kevin, et al.
(author)
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Holocene demographic fluctuations, climate and erosion in the Mediterranean : A meta data-analysis
- 2019
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In: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 29:5, s. 864-885
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Journal article (peer-reviewed)abstract
- As part of the Changing the Face of the Mediterranean Project, we consider how human pressure and concomitant erosion has affected a range of Mediterranean landscapes between the Neolithic and, in some cases, the post-medieval period. Part of this assessment comprises an investigation of relationships among palaeodemographic data, evidence for vegetation change and some consideration of rapid climate change events. The erosion data include recent or hitherto unpublished work from the authors. Where possible, we consider summed probabilities of 14C dates as well as the first published synthesis of all known optically stimulated luminescence dated sequences. The results suggest that while there were some periods when erosion took place contemporaneously across a number of regions, possibly induced by climate changes, more often than not, we see a complex and heterogeneous interplay of demographic and environmental changes that result in a mixed pattern of erosional activity across the Mediterranean.
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