| 1. |
- Cui, Qiao-Yu, et al.
(author)
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A case study of the role of climate, humans, and ecological setting in Holocene fire history of northwestern Europe
- 2015
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In: Science China. Earth Sciences. - : Springer Science and Business Media LLC. - 1674-7313 .- 1869-1897. ; 58:2, s. 195-210
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Journal article (peer-reviewed)abstract
- We present the major results from studies of fire history over the last 11000 years (Holocene) in southern Sweden, on the basis of palaeoecological analyses of peat sequences from three small peat bogs. The main objective is to emphasize the value of multiple, continuous sedimentary records of macroscopic charcoal (macro-C) for the reconstruction of local to regional past changes in fire regimes, the importance of multi-proxy studies, and the advantage of model-based estimates of plant cover from pollen data to assess the role of tree composition and human impact in fire history. The chronologies at the three study sites are based on a large number of C-14 dates from terrestrial plant remains and age-depth models are achieved using Bayesian statistics. Fire history is inferred from continuous records of macro-C and microscopic charcoal counts on pollen slides. The Landscape Reconstruction Algorithm (LRA) for pollen-based quantitative reconstruction of local vegetation cover is applied on the three pollen records for plant cover reconstruction over the entire Holocene. The results are as follows: (1) the long-term trends in fire regimes are similar between sites, i.e., frequent fires during the early Holocene until ca. 9 ka BP, low fire frequency during the mid-Holocene, and higher fire frequency from ca. 2.5 ka BP; (2) this broad trend agrees with the overall fire history of northwestern and western Europe north of the Mediterranean area, and is due to climate forcing in the early and mid-Holocene, and to anthropogenic land-use in the late Holocene; (3) the LRA estimates of plant cover at the three sites demonstrate that the relative abundance of pine played a primordial role in the early and mid-Holocene fire history; and (4) the between-site differences in the charcoal records and inferred fire history are due to local factors (i.e., relative abundance of pine, geomorphological setting, and anthropogenic land-use) and taphonomy of charcoal deposition in the small peat bogs. It is shown that continuous macro-C records are most useful to disentangle local from regional-subcontinental fire history, and climate-induced from human-induced fire regimes, and that pollen-based LRA estimates of local plant cover are more adequate than pollen percentages for the assessment of the role of plant composition on fire history.
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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. |
- Cui, Qiao-Yu, et al.
(author)
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Historical land-use and landscape change in southern Sweden and implications for present and future biodiversity
- 2014
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In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 4:18, s. 3555-3570
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Journal article (peer-reviewed)abstract
- The two major aims of this study are (1) To test the performance of the Landscape Reconstruction Algorithm (LRA) to quantify past landscape changes using historical maps and related written sources, and (2) to use the LRA and map reconstructions for a better understanding of the origin of landscape diversity and the recent loss of species diversity. Southern Sweden, hemiboreal vegetation zone. The LRA was applied on pollen records from three small bogs for four time windows between AD 1700 and 2010. The LRA estimates of % cover for woodland/forest, grassland, wetland, and cultivated land were compared with those extracted from historical maps within 3-km radius around each bog. Map-extracted land-use categories and pollen-based LRA estimates (in % cover) of the same land-use categories show a reasonable agreement in several cases; when they do not agree, the assumptions used in the data (maps)-model (LRA) comparison are a better explanation of the discrepancies between the two than possible biases of the LRA modeling approach. Both the LRA reconstructions and the historical maps reveal between-site differences in landscape characteristics through time, but they demonstrate comparable, profound transformations of the regional and local landscapes over time and space due to the agrarian reforms in southern Sweden during the 18th and 19th centuries. The LRA was found to be the most reasonable approach so far to reconstruct quantitatively past landscape changes from fossil pollen data. The existing landscape diversity in the region at the beginning of the 18th century had its origin in the long-term regional and local vegetation and land-use history over millennia. Agrarian reforms since the 18th century resulted in a dramatic loss of landscape diversity and evenness in both time and space over the last two centuries leading to a similarly dramatic loss of species (e.g., beetles).
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| 5. |
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| 6. |
- Cui, Qiao-Yu, et al.
(author)
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The role of tree composition in Holocene fire history of the hemiboreal and southern boreal zones of southern Sweden, as revealed by the application of the Landscape Reconstruction Algorithm : Implications for biodiversity and climate-change issues
- 2013
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In: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 23:12, s. 1747-1763
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Journal article (peer-reviewed)abstract
- We present a quantitative reconstruction of local forest history at two sites, Stavsåkra (hemiboreal zone) and Storasjö (southern boreal zone), in southern Sweden (province of Småland) to evaluate possible causes of contrasting Holocene fire histories in mid- and late Holocene. The Landscape Reconstruction Algorithm (LRA) is applied to evaluate between-site differences in the relative abundance of deciduous trees and Pinus (pine) and landscape/woodland openness during the Holocene. The LRA estimates of local vegetation abundance are compared with other proxies of local vegetation, that is, plant and beetle remains. The LRA results suggest that Pinus was a major tree taxon in the woodlands of Storasjö during mid- and late Holocene, while Tilia(linden) and Betula (birch) were dominant at Stavsåkra. The contrasting fire histories are shown to be strongly related to between-site differences in tree composition during mid-Holocene, 4000–2000 BC in particular. The archaeological/historical and beetle data indicate contrasting land uses from c. 1000BC (late Bronze Age/early Iron Age), grazing in open Calluna heaths at Stavsåkra and woodland grazing at Storasjö. Between-site differences in fire historyduring late Holocene were likely due to different land-use practices. Between-site differences in tree composition in mid-Holocene are best explainedby local climatic and geological/geomorphological differences between the hemiboreal and southern boreal zones of Småland, which might also be the primary cause of between-site differences in land-use histories during late Holocene. Maintenance of biodiversity at the landscape scale in the studyarea requires that existing old pine woodlands and Calluna heath are managed with fire and cattle grazing. Further climate warming might lead to higherprobabilities of climate-induces fire, in particular in pine-dominated woodlands.
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| 7. |
- Gaillard, Marie-José, et al.
(author)
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From land cover-climate relationships at the subcontinental scale to land cover-environment relationships at the regional and local spatial scale – the contribution of pollen-based quantitative reconstructions of vegetation cover using the Landscape Reconstruction Algorithm approach
- 2014
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In: Towards a more accurate quantification of human-environment interactions in the past. ; , s. 25-26
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Conference paper (peer-reviewed)abstract
- The Landscape Reconstruction Algorithm (Sugita 2007a,b) includes two models, REVEALS (Regional Estimates of VEgetation Abundance from Large Sites) that estimates vegetation abundance (% cover) within an area of ca. 100 km x 100 km, and LOVE (LOcal Vegetation Estimates) that estimates vegetation abundance at the local spatial scale, i.e. within the Relevant Source Area of Pollen (RSAP sensu Sugita, 2004) that is the smallest area around the study site for which the reconstruction is valid. The RSAP is estimated by the LOVE model and varies between sites and vegetation settings; so far, it was estimated to vary between < 1 - < 10 km in most ecological settings of the Holocene in NW Europe. We used the REVEALS model and over 600 pollen records from pollen data bases and individual researchers to reconstruct land-cover in NW Europe N of the Alps for key time windows of the Holocene in order to assess model-based reconstructions of anthropogenic land-cover change (ALCC) (e.g. Kaplan et al., 2009) and model (LPJ-GUESS) simulations of past potential (climate-induced vegetation), and to study past land cover – climate interactions using a regional climate model (RCA3). We used the REVEALS model and the complete LRA approach (REVEALS + LOVE models) along with two pollen records from large lakes and three pollen records from small bogs to reconstruct the local-scale land-cover in central Småland, southern Sweden, to study the relationship between vegetation composition, fire, climate and human impact at the regional and local spatial scales with the objective to discuss biodiversity issues. Our results suggest that i) past subcontinental to regional ALCC did influence regional climate through biogeophysical processes at the landatmosphere interface (Strandberg et al., submitted), and ii) local land-cover change, both natural and anthropogenic, govern environmental changes such as fire and biodiversity (Cui et al., 2013; Cui et al., submitted).
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| 8. |
- Gaillard, Marie-José, et al.
(author)
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The potential of pollen-based quantitative vegetation reconstructions in studies of past human settlements and use of resources – examples from Europe
- 2015
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In: Geophysical Research Abstracts.
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Conference paper (peer-reviewed)abstract
- There is a long tradition of collaboration between palaeoecologists and archaeologists in many parts of the world with the purpose of reconstructing the environment of humans through time and the study of the interactions between humans and their environment. Vegetation (i.e. vegetated landscapes and plants) has long been one of the most important parts of the environment for humans’ resources. Thanks to the interpretation of palaeoecological data such as pollen and plant macrofossils, it is well known that humans have used plants for their subsistence and formed many landscapes of the Earth through their activities over many millennia. Pollen analysis in particular has been used to reconstruct the landscapes of humans in order i) to learn something on their use of the landscape for building material, grazing and food (e.g. woods, grazed land, cultivated fields), and ii) to understand their influence on the landscape through deforestation in particular. Pollen data as proxy records of vegetation have been very useful to provide qualitative descriptions of cultural landscapes through time in terms of the presence of major tree, shrub and herb species, and the character of the landscape, wooded, “half-wooded” (or partly wooded), and primarily open (poorly wooded) (1). Efforts to calibrate pollen onto land-use in the 1990ies has made possible to provide more precise and detailed interpretation of pollen records in terms of land-use type (2). However, when it came to questions related to the size of cultivated land or grazed land in relation to wooded land, interpretation of pollen records has been problematic until recently. The non-linear relationship between pollen and vegetation due to inter-taxonomic differences in pollen productivity and pollen dispersion and deposition characteristics of plant taxa has long hampered estimation of the percentage cover of plant taxa or landscape units in the past. Thanks torecent developments in pollen-vegetation modelling, a new approach - the Landscape Reconstruction Algorithm (LRA) (3, 4) - makes it possible to estimate the cover of plant taxa or landscape units at both regional and local spatial scales using pollen records. The LRA has been tested and applied in various types of studies in Europe in particular. Examples from Europe and Scandinavia show that pollen-based quantitative reconstructions of vegetation cover, in combination with other palaeoecological records such as insect and plant macroremains, show the great potential of such studies to provide new insights on the use of landscapes and vegetation by humans in the past and its environmental consequences at both regional and local spatial scales (5, 6). These results provide a new environmental framework for the discussion and testing of hypotheses based on archaeological data.
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| 9. |
- Li, Furong, et al.
(author)
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A Review of Relative Pollen Productivity Estimates From Temperate China for Pollen-Based Quantitative Reconstruction of Past Plant Cover
- 2018
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In: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 9
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Research review (peer-reviewed)abstract
- Model-based quantitative reconstruction of past plant cover in Europe has shown great potential for: (i) testing hypotheses related to Holocene vegetation dynamics, biodiversity, and their relationships with climate and land use; (ii) studying long term interactions between climate and land use. Similar model-based quantitative reconstruction of plant cover in China has been restricted due to the lack of standardized datasets of existing estimates of relative pollen productivity (RPP). This study presents the first synthesis of all RPP values available to date for 39 major plant taxa from temperate China and proposes standardized RPP datasets that can be used for model-based quantitative reconstructions of past plant cover using fossil pollen records for the region. We review 11 RPP studies in temperate China based on modern pollen and related vegetation data around the pollen samples. The study areas include meadow, steppe and desert vegetation, various woodland types, and cultural landscapes. We evaluate the strategies of each study in terms of selection of study areas and distribution of study sites; pollen- and vegetation-data collection in field; vegetation-data collection from satellite images and vegetation maps; and data analysis. We compare all available RPP estimates, select values based on precise rules and calculate mean RPP estimates. We propose two standardized RPP datasets for 31 (Alt1) and 29 (Alt2) plant taxa. The ranking of mean RPPs (Alt-2) relative to Poaceae (= 1) for eight major taxa is: Artemisia (21) > Pinus (18.4) > Betula (12.5) > Castanea (11.5) > Elaeagnaceae (8.8) > Juglans (7.5) > Compositae (4.5) > Amaranthaceae/Chenopodiaceae (4). We conclude that although RPPs are comparable between Europe and China for some genera and families, they can differ very significantly, e.g., Artemisia, Compositae, and Amaranthaceae/Chenopodiaceae. For some taxa, we present the first RPP estimates e.g. Castanea, Elaeagnaceae, and Juglans. The proposed standardized RPP datasets are essential for model-based reconstructions of past plant cover using fossil pollen records from temperate China.
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| 10. |
- Marlon, Jennifer, et al.
(author)
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Humans and fire : Consequences of anthropogenic burning during the past 2 Ka
- 2010
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In: PAGES News. - 1811-1602 .- 1811-1610. ; 18:2, s. 80-82
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Journal article (peer-reviewed)abstract
- The case studies here illustrate how the timing and consequences of anthropogenic interventions in natural fire regimes vary greatly across space and depend heavily on local ecological context; they also demonstrate why the cumulativeglobal effects of anthropogenic impacts on fire regimes have been difficult to detect until the past two centuries (Fig. 2). Increasing efforts to synthesize existing paleoecological records (Power et al., 2009), and combine multiproxy evidence of paleoenvironmental changes with archeological data and modeling promise valuable advancements in our understanding of coupled human-natural systems in the past.
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