| 1. |
- Feurdean, Angelica, et al.
(författare)
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Long-term land-cover/use change in a traditional farming landscape in Romania inferred from pollen data, historical maps and satellite images
- 2017
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Ingår i: Regional Environmental Change. - : Springer Science and Business Media LLC. - 1436-3798 .- 1436-378X. ; 17:8, s. 2193-2207
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Tidskriftsartikel (refereegranskat)abstract
- Traditional farming landscapes in the temperate zone that have persisted for millennia can be exceptionally species-rich and are therefore key conservation targets. In contrast to Europe’s West, Eastern Europe harbours widespread traditional farming landscapes, but drastic socio-economic and political changes in the twentieth century are likely to have impacted these landscapes profoundly. We reconstructed long-term land-use/cover and biodiversity changes over the last 150 years in a traditional farming landscape of outstanding species diversity in Transylvania. We used the Regional Estimates of Vegetation Abundance from Large Sites model applied to a pollen record from the Transylvanian Plain and a suite of historical and satellite-based maps. We documented widespread changes in the extent and location of grassland and cropland, a loss of wood pastures as well as a gradual increase in forest extent. Land management in the socialist period (1947–1989) led to grassland expansion, but grassland diversity decreased due to intensive production. Land-use intensity has declined since the collapse of socialism in 1989, resulting in widespread cropland abandonment and conversion to grassland. However, these trends may be temporary due to both ongoing woody encroachment as well as grassland management intensification in productive areas. Remarkably, only 8% of all grasslands existed throughout the entire time period (1860–2010), highlighting the importance of land-use history when identifying target areas for conservation, given that old-growth grasslands are most valuable in terms of biodiversity. Combining datasets from different disciplines can yield important additional insights into dynamic landscape and biodiversity changes, informing conservation actions to maintain these species-rich landscapes in the longer term.
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| 2. |
- Feurdean, Angelica, et al.
(författare)
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Origin of the forest steppe and exceptional grassland diversity in Transylvania (central-eastern Europe)
- 2015
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Ingår i: Journal of Biogeography. - : Wiley. - 1365-2699 .- 0305-0270. ; 42:5, s. 951-963
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Tidskriftsartikel (refereegranskat)abstract
- Aim The forest steppe of the Transylvanian Plain is a landscape of exceptionally diverse steppe-like and semi-natural grasslands. Is this vegetation a remnant of a once continuous temperate forest extensively cleared by humans, or has the area, since the last glacial, always been a forest steppe? Understanding the processes that drive temperate grassland formation is important because effective management of this biome is critical to the conservation of the European cultural landscape. Location Lake Stiucii, north-western Romania, central-eastern Europe. Methods We analysed multi-proxy variables (pollen, coprophilous fungi, plant macroremains, macrocharcoal) from a 55,000year discontinuous sequence (c. 55,000-35,000; 13,000-0cal. yr bp), integrating models of pollen-based vegetation cover, biome reconstruction, global atmospheric simulations and archaeological records. Results Needleleaf woodland occurred during glacial Marine Isotope Stage (MIS) 3, but contracted at the end of this period. Forest coverage of c. 55% (early Holocene) and 65% (mid-Holocene) prevailed through the Holocene, but Bronze Age humans extensively cleared forests after 3700cal. yr bp. Forest coverage was most widespread between 8600 and 3700cal. yr bp, whereas grasses, steppe and xerothermic forbs were most extensive between 11,700 and 8600cal. yr bp and during the last 3700cal. yr bp. Cerealia pollen indicate the presence of arable agriculture by c. 7000cal. yr bp. Main conclusions We have provided the first unequivocal evidence for needleleaf woodland during glacial MIS 3 in this region. Extensive forests prevailed prior to 3700cal. yr bp, challenging the hypothesis that the Transylvanian lowlands were never wooded following the last glaciation. However, these forests were never fully closed either, reflecting dry growing season conditions, recurrent fires and anthropogenic impacts, which have favoured grassland persistence throughout the Holocene. The longevity of natural and semi-natural grasslands in the region may explain their current exceptional biodiversity. This longer-term perspective implies that future climatic warming and associated fire will maintain these grasslands.
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| 3. |
- Grindean, Roxana, et al.
(författare)
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Relative pollen productivity estimates in the forest steppe landscape of southeastern Romania
- 2019
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Ingår i: Review of Palaeobotany and Palynology. - : Elsevier BV. - 0034-6667. ; 264, s. 54-63
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Tidskriftsartikel (refereegranskat)abstract
- Estimates of relative pollen productivity (RPP) represent key input parameters for model-based quantitative reconstructions of past vegetation cover. In this study, we provide the first RPP estimates for 13 taxa from the forest steppe ecoregion in southeastern Romania (southeastern Europe). We used modern pollen assemblages from 26 points together with vegetation surveys and mapping, covering a 1.5 km radius around each sampling site. We have estimated the relevant source area of pollen (RSAP) and pollen productivity for 13 taxa relative to Poaceae using the ERV (Extended R-value model), sub-model 3, as this model shows the best goodness of fit. The estimated RSAP is about 100 m and falls within the range of RSAP estimates of moss pollsters and forest hollows from other RPP-related studies. Results show that Rubiaceae (7.97), Apiaceae (5.91), Artemisia (5.89) and Fraxinus (2.99) are high pollen producers compared to Poaceae, while Plantago lanceolata (0.58), Fabaceae (0.40), Acer (0.30), Rosaceae (0.29), Carpinus orientalis (0.24), Cerealia (0.22) and Asteraceae (0.16) are low pollen producers with lower RPPs than Poaceae. Quercus (1.10) has a pollen productivity close to that of Poaceae. The RPPs for Carpinus orientalis and Fabaceae are published here the first time for Europe. The high pollen producing plants include both entomophilous and anemophilous species, while the low pollen producers are mostly entomophilous species. Our results form an essential contribution to improving the accuracy of quantitative reconstruction of forest steppe ecoregion in Europe and generally in regions with a similar climate and vegetation setting.
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| 4. |
- Vannière, Boris, et al.
(författare)
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7000-year human legacy of elevation-dependent European fire regimes
- 2016
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 132, s. 206-212
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Tidskriftsartikel (refereegranskat)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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