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  1. Climate changes during the Lateglacial in South Europe: new insights based on pollen and brGDGTs of Lake Matese in Italy

    The Lateglacial (14,700-11,700 cal BP) is a key climate period marked by rapid but contrasted changes in the Northern Hemisphere. Indeed, regional climate differences have been evidenced during the Lateglacial in Europe and the Northern Mediterranean... mehr

     

    The Lateglacial (14,700-11,700 cal BP) is a key climate period marked by rapid but contrasted changes in the Northern Hemisphere. Indeed, regional climate differences have been evidenced during the Lateglacial in Europe and the Northern Mediterranean areas. However, past climate patterns are still debated since temperature and precipitation changes are poorly investigated towards the lower European latitudes. Lake Matese in Southern Italy is a key site in the Central Mediterranean to investigate climate patterns during the Lateglacial. This study aims to reconstruct climate changes and their impacts at Matese using a multi-proxy approach including magnetic susceptibility, geochemistry (XRF core scanning), pollen data and molecular biomarkers like branched Glycerol Dialkyl Glycerol Tetraethers (brGDGTs). Palaeotemperatures and -precipitation patterns are quantitatively inferred from pollen assemblages (multi-method approach: Modern Analogue Technique, Weighted Averaging Partial Least Squares regression, Random Forest, and Boosted Regression Trees) and brGDGTs calibrations. The results are compared to a latitudinal selection of regional climate reconstructions in Italy to better understand climate processes in Europe and in the circum-Mediterranean region. A warm Bølling–Allerød and a marked cold Younger Dryas are revealed in all climate reconstructions inferred from various proxies (chironomids, ostracods, speleothems, pollen, brGDGTs), showing no latitudinal differences in terms of temperatures across Italy. During the Bølling–Allerød, no significant changes in terms of precipitation are recorded, however, a contrasted pattern is visible during the Younger Dryas. Slightly wetter conditions are recorded south of latitude 42°N whereas dry conditions are recorded north of latitude 42°N. During the Younger Dryas, cold conditions can be attributed to the southward position of North Atlantic sea-ice and of the Polar Frontal JetStream whereas the increase of precipitation is Southern Italy seems to be linked to ...

     

    Export in Literaturverwaltung
    Quelle: BASE Fachausschnitt AVL
    Sprache: Englisch
    Medientyp: Konferenzveröffentlichung; Weitere
    Format: Online
    Übergeordneter Titel: INQUA ; https://cnrs.hal.science/hal-04168314 ; INQUA, Jul 2023, Roma, Italy
    Schlagworte: [SDE]Environmental Sciences
  2. Using plant functional traits in paleoecology: a calibration study from Arid Central Asia

    The necessity of accurate past climate reconstructions for climate modelling is a key issue in (paleo)ecology. Especially, dryland such as Arid Central Asian deserts may spread in the next decades in surrounding steppes due to aridification. Several... mehr

     

    The necessity of accurate past climate reconstructions for climate modelling is a key issue in (paleo)ecology. Especially, dryland such as Arid Central Asian deserts may spread in the next decades in surrounding steppes due to aridification. Several methods already exist to convert pollen in quantitative climate (transfer functions) and biome (biomization). However, these methods are impeded by numerous biases, which could be overcome by current breakthrough in plant functional response to climate understanding.Few past pollen studies attempt to merge plant functional traits with pollen samples in order to reconstruct paleo-trait cover and functional vegetation dynamics. However, this approach has not been tested using modern samples. Especially, since the taxonomic resolution used in ecology is not the same as the one used in pollen studies (usually family or genus pollen identification), whether the phenotypic space of extant vegetation is consistent with that derived from pollen modern samples remains an open question.Here, we tested the performance of combining paleoecology and plant functional ecology to validate the use of pollen to infer the phenotypic space of past vegetation. The pollen surface sites from Arid Central Asia (n = 2393) have been extracted and the pollen-types have been used to aggregate traits (height, leaf area, leaf nitrogen, seed mass, specific leaf area and stem specific density from TRY, BIEN and GIFT databases). Then, the community-weighted mean (CWM) traits have been calculated using the pollen fractional abundances. These pollen-CWM traits have been compared with the vegetation-CWM (n = 21347). Finally, both have been related to current climate parameters.The preliminary results of this study show that the trait values aggregated by pollen-types respect the same plant economic spectrum than observed in botanical taxonomic resolution. Moreover, it validates the use of pollen as equivalent of vegetation plots to calculate the CWM. It also appears that the scheme of aggregation ...

     

    Export in Literaturverwaltung
    Quelle: BASE Fachausschnitt AVL
    Sprache: Englisch
    Medientyp: Konferenzveröffentlichung; Weitere
    Format: Online
    Übergeordneter Titel: INQUA ; https://hal.science/hal-04168473 ; INQUA, Jul 2023, Roma, Italy
    Schlagworte: [SDE]Environmental Sciences