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The transformation of the forest steppe in the lower Danube Plain of southeastern Europe : 6000 years of vegetation and land use dynamics

Feurdean, Angelica ; Grindean, Roxana ; Florescu, Gabriela ; Tantǎu, Ioan ; Niedermeyer, Eva M. ; Diaconu, Andrei Cosmin ; Hutchinson, Simon M. ; Nielsen, Anne Brigitte LU orcid ; Sava, Tiberiu and Panait, Andrei , et al. (2021) In Biogeosciences 18(3). p.1081-1103
Abstract

Forest steppes are dynamic ecosystems, highly susceptible to changes in climate, disturbances and land use. Here we examine the Holocene history of the European forest steppe ecotone in the lower Danube Plain to better understand its sensitivity to climate fluctuations, fire and human impact, and the timing of its transition into a cultural forest steppe. We used multi-proxy analyses (pollen, n-alkanes, coprophilous fungi, charcoal and geochemistry) of a 6000- year sequence from Lake Oltina (southeastern Romania) combined with a REVEALS (Regional Estimates of Vegetation Abundance from Large Sites) model of quantitative vegetation cover. We found a greater tree cover, composed of xerothermic (Carpinus orientalis and Quercus) and... (More)

Forest steppes are dynamic ecosystems, highly susceptible to changes in climate, disturbances and land use. Here we examine the Holocene history of the European forest steppe ecotone in the lower Danube Plain to better understand its sensitivity to climate fluctuations, fire and human impact, and the timing of its transition into a cultural forest steppe. We used multi-proxy analyses (pollen, n-alkanes, coprophilous fungi, charcoal and geochemistry) of a 6000- year sequence from Lake Oltina (southeastern Romania) combined with a REVEALS (Regional Estimates of Vegetation Abundance from Large Sites) model of quantitative vegetation cover. We found a greater tree cover, composed of xerothermic (Carpinus orientalis and Quercus) and temperate (Carpinus betulus, Tilia, Ulmus and Fraxinus) tree taxa, between 6000 and 2500 cal yr BP. Maximum tree cover (~50 %), dominated by C. orientalis occurred between 4200 and 2500 cal yr BP at a time of wetter climatic conditions and moderate fire activity. Compared to other European forest steppe areas, the dominance of C. orientalis represents the most distinct feature of the woodland's composition at this time. Tree loss was underway by 2500 yr BP (Iron Age), with the REVEALS model indicating a fall to ~20% tree cover from the Late Holocene forest maximum, linked to clearance for agriculture, while climate conditions remained wet. Biomass burning increased markedly at 2500 cal yr BP, suggesting that fire was regularly used as a management tool until 1000 cal yr BP when woody vegetation became scarce. A sparse tree cover, with only weak signs of forest recovery, then became a permanent characteristic of the lower Danube Plain, highlighting more or less continuous anthropogenic pressure. The timing of anthropogenic ecosystem transformation here (2500 cal yr BP) falls between that in centraleastern (between 3700 and 3000 cal yr BP) and eastern (after 2000 cal yr BP) Europe. Our study is the first quantitative land cover estimate at the forest steppe ecotone in southeastern Europe spanning 6000 years. It provides critical empirical evidence that, at a broad spatial scale, the present-day forest steppe and woodlands reflect the potential natural vegetation in this region under current climate conditions. However, the extent of tree cover and its composition have been neither stable in time nor shaped solely by the climate. Consequently, vegetation change must be seen as dynamic and reflecting wider changes in environmental conditions including natural disturbances and human impact.

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type
Contribution to journal
publication status
published
subject
keywords
Pollen analysis, landscape reconstruction algorithm, Forest steppe
in
Biogeosciences
volume
18
issue
3
article number
10812021
pages
23 pages
publisher
Copernicus GmbH
external identifiers
  • scopus:85101480222
ISSN
1726-4170
DOI
10.5194/bg-18-1081-2021
language
English
LU publication?
yes
additional info
Funding Information: Financial support. This research has been supported by the Publisher Copyright: © 2021 Copernicus GmbH. All rights reserved. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
id
462d8210-21b0-4154-909e-29c0df54aeaa
date added to LUP
2021-05-17 17:43:51
date last changed
2023-02-21 10:00:23
@article{462d8210-21b0-4154-909e-29c0df54aeaa,
  abstract     = {{<p>Forest steppes are dynamic ecosystems, highly susceptible to changes in climate, disturbances and land use. Here we examine the Holocene history of the European forest steppe ecotone in the lower Danube Plain to better understand its sensitivity to climate fluctuations, fire and human impact, and the timing of its transition into a cultural forest steppe. We used multi-proxy analyses (pollen, n-alkanes, coprophilous fungi, charcoal and geochemistry) of a 6000- year sequence from Lake Oltina (southeastern Romania) combined with a REVEALS (Regional Estimates of Vegetation Abundance from Large Sites) model of quantitative vegetation cover. We found a greater tree cover, composed of xerothermic (Carpinus orientalis and Quercus) and temperate (Carpinus betulus, Tilia, Ulmus and Fraxinus) tree taxa, between 6000 and 2500 cal yr BP. Maximum tree cover (~50 %), dominated by C. orientalis occurred between 4200 and 2500 cal yr BP at a time of wetter climatic conditions and moderate fire activity. Compared to other European forest steppe areas, the dominance of C. orientalis represents the most distinct feature of the woodland's composition at this time. Tree loss was underway by 2500 yr BP (Iron Age), with the REVEALS model indicating a fall to ~20% tree cover from the Late Holocene forest maximum, linked to clearance for agriculture, while climate conditions remained wet. Biomass burning increased markedly at 2500 cal yr BP, suggesting that fire was regularly used as a management tool until 1000 cal yr BP when woody vegetation became scarce. A sparse tree cover, with only weak signs of forest recovery, then became a permanent characteristic of the lower Danube Plain, highlighting more or less continuous anthropogenic pressure. The timing of anthropogenic ecosystem transformation here (2500 cal yr BP) falls between that in centraleastern (between 3700 and 3000 cal yr BP) and eastern (after 2000 cal yr BP) Europe. Our study is the first quantitative land cover estimate at the forest steppe ecotone in southeastern Europe spanning 6000 years. It provides critical empirical evidence that, at a broad spatial scale, the present-day forest steppe and woodlands reflect the potential natural vegetation in this region under current climate conditions. However, the extent of tree cover and its composition have been neither stable in time nor shaped solely by the climate. Consequently, vegetation change must be seen as dynamic and reflecting wider changes in environmental conditions including natural disturbances and human impact.</p>}},
  author       = {{Feurdean, Angelica and Grindean, Roxana and Florescu, Gabriela and Tantǎu, Ioan and Niedermeyer, Eva M. and Diaconu, Andrei Cosmin and Hutchinson, Simon M. and Nielsen, Anne Brigitte and Sava, Tiberiu and Panait, Andrei and Braun, Mihaly and Hickler, Thomas}},
  issn         = {{1726-4170}},
  keywords     = {{Pollen analysis; landscape reconstruction algorithm; Forest steppe}},
  language     = {{eng}},
  month        = {{02}},
  number       = {{3}},
  pages        = {{1081--1103}},
  publisher    = {{Copernicus GmbH}},
  series       = {{Biogeosciences}},
  title        = {{The transformation of the forest steppe in the lower Danube Plain of southeastern Europe : 6000 years of vegetation and land use dynamics}},
  url          = {{http://dx.doi.org/10.5194/bg-18-1081-2021}},
  doi          = {{10.5194/bg-18-1081-2021}},
  volume       = {{18}},
  year         = {{2021}},
}