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  • 2010-2014  (42)
  • 1995-1999  (18)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Vegetation history and archaeobotany 6 (1997), S. 117-131 
    ISSN: 1617-6278
    Keywords: Marine palynology ; Vegetation history ; Climate change ; Ocean currents ; Southwest Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Archaeology , Biology
    Notes: Abstract A continuous palynological record from the marine core GeoB1016-3 from the Angola Basin reveals the regional vegetation and climate history of the last 300 ka. Pollen and spores found at the studied site have their source areas in the different vegetation zones of the adjacent part of the West African continent. Those vegetation zones comprise tropical rain forest, coastal mangrove swamp, Miombo woodland, dry forest, Afromontane forest, desert and semi-desert. The main pollen transport agent is the southeast trade wind system. Ocean currents also partly play a role in transporting pollen and spores. During the interglacial periods, ocean currents also transported palynomorphs southward. During the glacial periods, increased trade winds are indicated by high influx of pollen and spores and high pollen percentages of Poaceae and taxa from desert and semidesert vegetations. Reconstruction of the geographical position of palaeo-vegetation zones shows that the northern boundary of the Namib Desert did not move north of 12°S during the last 300 ka. This implies that northward shifts of the Angola-Benguela Front did not pass the latitude of 12°S.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1617-6278
    Keywords: Marine pollen record ; S.W. Africa ; Climate change ; Human impact ; Late Pleistocene ; Holocene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Archaeology , Biology
    Notes: Abstract A high resolution marine pollen record from site GeoB1023, west of the northern Namib desert provides data on vegetation and climate change for the last 21 ka at an average resolution of 185 y. Pollen and spores are mainly delivered to the site by the Cunene river and by surface and mid-tropospheric wind systems. The main pollen source areas are located between 13°S and 21°S, which includes the northern Namib desert and semi-desert, the Angola-northern Namibian highland, and the north-western Kalahari. The pollen spectra reflect environmental changes in the region. The last glacial maximum (LGM) was characterised by colder and more arid conditions than at present, when a vegetation with temperate elements such as Asteroideae, Ericaceae, and Restionaceae grew north of 21°S. At 17.5 ka cal. B.P., an amelioration both in temperature and humidity terminated the LGM but, in the northern Kalahari, mean annual rainfall in the interval 17.5-14.4 ka cal. B.P. was probably 100–150 mm lower than at present (400–500 mm/y). The Late-glacial to early Holocene transition includes two arid periods, i.e. 14.4–12.5 and 10.9–9.3 ka cal. B.P. The last part of the former period may be correlated with the Younger Dryas. The warmest and most humid period in the Holocene occurred between 6.3 and 4.8 ka cal. B.P. During the last 2000 years, human impact, as reflected by indications of deforestation, enhanced burning and overgrazing, progressively intensified.
    Type of Medium: Electronic Resource
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  • 3
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    Elsevier
    In:  EPIC3Earth and Planetary Science Letters, Elsevier, 375, pp. 408-417, ISSN: 0012-821X
    Publication Date: 2014-06-25
    Description: The Miocene expansion of C4 plants (mainly tropical grasses) between 8 and 4 million years (Ma) remains an enigma since regional differences in the timing of the expansion rules out decreased CO2 (pCO2) as a dominant forcing [e.g. Tipple and Pagani, 2007. The early origins of terrestrial C4 photosynthesis. Annu. Rev. Earth Planet. Sci. 35, 435–461]. Other environmental factors, such as low-latitude aridity and seasonality have been proposed to explain the low tree versus grass ratio found in savannahs and tropical grasslands of the world, but conclusive evidence is missing. Here we use pollen and stable carbon (δ13C) and hydrogen (δD) isotope ratios of terrestrial plant wax from a South Atlantic sediment core (ODP Site 1085) to reconstruct Miocene to Pliocene changes of vegetation and rainfall regime of western southern Africa. Our results reveal changes in the relative amount of precipitation and indicate a shift of the main moisture source from the Atlantic to the Indian Ocean during the onset of a major aridification 8 Ma ago. We emphasize the importance of declining precipitation during the expansion of C4 and CAM (mainly succulent) vegetation in South Africa. We suggest that the C4 plant expansion resulted from an increased equator-pole temperature gradient caused by the initiation of strong Atlantic Meridional Overturning Circulation following the shoaling of the Central American Seaway during the Late Miocene.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
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    PANGAEA
    In:  Supplement to: Dupont, Lydie M; Rommerskirchen, Florian; Mollenhauer, Gesine; Schefuß, Enno (2013): Miocene to Pliocene changes in South African hydrology and vegetation in relation to the expansion of C4 plants. Earth and Planetary Science Letters, 375, 408-417, https://doi.org/10.1016/j.epsl.2013.06.005
    Publication Date: 2023-03-03
    Description: Pollen and stable carbon (d13C) and hydrogen (dD) isotope ratios of terrestrial plant wax from the South Atlantic sediment core, ODP Site 1085, is used to reconstruct Miocene to Pliocene changes of vegetation and rainfall regime of western southern Africa. Our results reveal changes in the relative amount of precipitation and indicate a shift of the main moisture source from the Atlantic to the Indian Ocean during the onset of a major aridification 8 Ma ago. We emphasise the importance of declining precipitation during the expansion of C4 and CAM (mainly succulent) vegetation in South Africa. We suggest that the C4 plant expansion resulted from an increased equator-pole temperature gradient caused by the initiation of strong Atlantic Meridional Overturning Circulation following the shoaling of the Central American Seaway during the Late Miocene.
    Keywords: Center for Marine Environmental Sciences; MARUM
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 5
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    PANGAEA
    In:  Supplement to: Handiani, Dian Noor; Paul, André; Dupont, Lydie M (2012): Tropical climate and vegetation changes during Heinrich Event 1: a model-data comparison. Climate of the Past, 8(1), 37-57, https://doi.org/10.5194/cp-8-37-2012
    Publication Date: 2023-01-13
    Description: Abrupt climate changes from 18 to 15 thousand years before present (kyr BP) associated with Heinrich Event 1 (HE1) had a strong impact on vegetation patterns not only at high latitudes of the Northern Hemisphere, but also in the tropical regions around the Atlantic Ocean. To gain a better understanding of the linkage between high and low latitudes, we used the University of Victoria (UVic) Earth System-Climate Model (ESCM) with dynamical vegetation and land surface components to simulate four scenarios of climate-vegetation interaction: the pre-industrial era, the Last Glacial Maximum (LGM), and a Heinrich-like event with two different climate backgrounds (interglacial and glacial). We calculated mega-biomes from the plant-functional types (PFTs) generated by the model to allow for a direct comparison between model results and palynological vegetation reconstructions. Our calculated mega-biomes for the pre-industrial period and the LGM corresponded well with biome reconstructions of the modern and LGM time slices, respectively, except that our pre-industrial simulation predicted the dominance of grassland in southern Europe and our LGM simulation resulted in more forest cover in tropical and sub-tropical South America. The HE1-like simulation with a glacial climate background produced sea-surface temperature patterns and enhanced inter-hemispheric thermal gradients in accordance with the "bipolar seesaw" hypothesis. We found that the cooling of the Northern Hemisphere caused a southward shift of those PFTs that are indicative of an increased desertification and a retreat of broadleaf forests in West Africa and northern South America. The mega-biomes from our HE1 simulation agreed well with paleovegetation data from tropical Africa and northern South America. Thus, according to our model-data comparison, the reconstructed vegetation changes for the tropical regions around the Atlantic Ocean were physically consistent with the remote effects of a Heinrich event under a glacial climate background.
    Keywords: Description; File name; File size; File type; Uniform resource locator/link to model result file
    Type: Dataset
    Format: text/tab-separated-values, 55 data points
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  • 6
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    PANGAEA
    In:  Supplement to: Handiani, Dian Noor; Paul, André; Prange, Matthias; Merkel, Ute; Dupont, Lydie M; Zhang, Xiao (2013): Tropical vegetation response to Heinrich Event 1 as simulated with the UVic ESCM and CCSM3. Climate of the Past, 9(4), 1683-1696, https://doi.org/10.5194/cp-9-1683-2013
    Publication Date: 2023-01-13
    Description: We investigated changes in tropical climate and vegetation cover associated with abrupt climate change during Heinrich Event 1 (HE1, ca. 17.5 ka BP) using two different global climate models: the University of Victoria Earth System-Climate Model (UVic ESCM) and the Community Climate System Model version 3 (CCSM3). Tropical South American and African pollen records suggest that the cooling of the North Atlantic Ocean during HE1 influenced the tropics through a southward shift of the rain belt. In this study, we simulated the HE1 by applying a freshwater perturbation to the North Atlantic Ocean. The resulting slowdown of the Atlantic Meridional Overturning Circulation was followed by a temperature seesaw between the Northern and Southern Hemispheres, as well as a southward shift of the tropical rain belt. The shift and the response pattern of the tropical vegetation around the Atlantic Ocean were more pronounced in the CCSM3 than in the UVic ESCM simulation. For tropical South America, opposite changes in tree and grass cover were modeled around 10° S in the CCSM3 but not in the UVic ESCM. In tropical Africa, the grass cover increased and the tree cover decreased around 15° N in the UVic ESCM and around 10° N in the CCSM3. In the CCSM3 model, the tree and grass cover in tropical Southeast Asia responded to the abrupt climate change during the HE1, which could not be found in the UVic ESCM. The biome distributions derived from both models corroborate findings from pollen records in southwestern and equatorial western Africa as well as northeastern Brazil.
    Keywords: Description; File name; File size; File type; Uniform resource locator/link to model result file
    Type: Dataset
    Format: text/tab-separated-values, 90 data points
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  • 7
    Publication Date: 2023-06-27
    Keywords: 175-1081A; Age, dated; Benguela Current, South Atlantic Ocean; Calculated from UK'37 (Müller et al, 1998); Center for Marine Environmental Sciences; DEPTH, sediment/rock; DRILL; Drilling/drill rig; Joides Resolution; Leg175; MARUM; n-Alkane C31, δ13C; n-Alkane C31, δ13C, standard deviation; n-Alkane C33, δ13C; n-Alkane C33, δ13C, standard deviation; Sample code/label; Sea surface temperature; Sea surface temperature, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 168 data points
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  • 8
    Publication Date: 2023-07-10
    Keywords: 175-1085A; Age model; Benguela Current, South Atlantic Ocean; Calculated; Calculated, see reference(s); Center for Marine Environmental Sciences; Depth, composite; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Joides Resolution; Leg175; MARUM; n-Alkane C31, δD; n-Alkane C31, δD, standard deviation; Sample code/label
    Type: Dataset
    Format: text/tab-separated-values, 369 data points
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  • 9
    Publication Date: 2023-06-27
    Keywords: 175-1081A; Age, dated; Amaranthaceae; Asteraceae undifferentiated; Benguela Current, South Atlantic Ocean; Center for Marine Environmental Sciences; Charcoal/(pollen + spores + charcoal) ratio; Cyperaceae; DEPTH, sediment/rock; DRILL; Drilling/drill rig; Joides Resolution; Leg175; MARUM; Poaceae; Pollen, woodland; Pollen and spores; Sample code/label; semidesert, pollen
    Type: Dataset
    Format: text/tab-separated-values, 781 data points
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  • 10
    Publication Date: 2023-07-10
    Keywords: 175-1085A; Age model; Benguela Current, South Atlantic Ocean; Calculated; Calculated, see reference(s); Center for Marine Environmental Sciences; Depth, composite; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Joides Resolution; Leg175; MARUM; n-Alkane C31, δ13C; n-Alkane C31, δ13C, standard deviation; Sample code/label
    Type: Dataset
    Format: text/tab-separated-values, 424 data points
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