Lateglacial to Early Holocene recursive aridity events in the SE Mediterranean Iberian Peninsula: The Salines playa lake case study (original) (raw)
Related papers
Comparison of selected, well-dated, lacustrine, speleothem and terrestrial pollen records spanning the Holocene onset and the Early Holocene (ca. 11.7e8 cal kyrs BP) in the Iberian Peninsula shows large hydrological fluctuations and landscape changes with a complex regional pattern in timing and intensity. Marine pollen records from Alboran, the Mediterranean and off shore Atlantic sites show a step-wise increase in moisture and forest during this transition. However, available continental records point to two main patterns of spatial and temporal hydrological variability: i) Atlantic-influenced sites located at the northwestern areas (Enol, Sanabria, Lucenza, PRD-4), characterized by a gradual increase in humidity from the end of the Younger Dryas to the Mid Holocene, similarly to most North Atlantic records; and ii) continental and Mediterranean-influenced sites (Laguna Grande, Villarquemado, Fuentillejo, Padul, Estanya, Banyoles, Salines), with prolonged arid conditions of variable temporal extension after the Younger Dryas, followed by an abrupt increase in moisture at 10-9 cal kyrs BP. Different local climate conditions influenced by topography or the variable sensitivity (gradual versus threshold values) of the proxies analyzed in each case are evaluated. Vegetation composition (conifers versus mesothermophilous taxa) and resilience would explain a subdued response of vegetation in central continental areas while in Mediterranean sites, insufficient summer moisture availability could not maintain high lake levels and promote mesophyte forest, in contrast to Atlantic-influenced areas. Comparison with available climate models, Greenland ice cores, North Atlantic marine sequences and continental records from Central and Northern Europe and the whole Mediterranean region underlines the distinctive character of the hydrological changes occurred in inner Iberia throughout the Early Holocene. The persistent arid conditions might be explained by the intensification of the summer drought due to the high seasonality contrast at these latitudes caused by the orbital-induced summer insolation maximum. New records, particularly from western and southernmost Iberia, and palaeoclimate models with higher spatial resolution would help to constrain these hypotheses.
Mid-Holocene vegetation and climatic history of the Iberian Peninsula
The Holocene, 21(1): 75-93, 2011
Authors: Ramon Pérez-Obiol, Guy Jalut, Ramon Julià, Albert Pèlachs, Mª José Iriarte, Thierry Otto, Begoña Hernández-Beloqui The aim of this research is to study the climate and vegetation history in the western Mediterranean, in the Iberian Peninsula, during the middle Holocene through pollen analysis. The origin of the deposits varied from the most xeric to more mesic Mediterranean environments. The timing, extent, and progress of the establishment of the Mediterranean climate have a degree of variability depending on the biogeographical region. Analyses of several pollen sequences reveal climatic transformations in the flora and vegetation between 7000 and 4000 cal. yr BP. Pollen concentrations have been used in some sequences to evaluate the order of magnitude in biomass changes through time. Three main spatial and taxonomic responses could be assumed: (1) in littoral regions, deciduous broadleaf trees were frequently dominant and then replaced by sclerophyllous and evergreen forests; (2) in continental regions and sub-Mediterranean mountains, the dominance of pine throughout the whole Holocene signals a change of less magnitude; and (3) in southeastern semi-arid Mediterranean regions, the main changes are reflected by alternation between steppe and shrub communities. The emplacement of the Mediterranean climate is reflected in an aridification process. A temporal first approach of Holocene climatic changes is proposed: a humid phase (12000–7000 cal. yr BP), a transition phase (7000–5500 cal. yr BP) and an aridification phase (5500 cal. yr BP–Present). According to archaeological data, natural changes in the forests favoured the environments suitable for human settlements, farming and sheepherding. Keywords: climate change, Holocene, Iberian Peninsula, Mediterranean, pollen analysis, semi-arid