Search results for "LD"
showing 10 items of 41748 documents
The metamorphic rocks of the Nunatak Viedma in the Southern Patagonian Andes: Provenance sources and implications for the early Mesozoic Patagonia-An…
2019
The Nunatak Viedma within the Southern Patagonian Icefield has been considered as a volcanic center based on its geomorphologic features, despite the fact that field explorations by Eric Shipton determined its metamorphic nature 70 years ago. We carried out fieldwork to characterize this isolated outcrop and performed the first U-Pb dating in detrital zircons from the basement rocks located inside the Southern Patagonian Icefield. We recognized very-low grade metamorphic rocks, corresponding principally to metapelites and metapsammites, and scarce metabasites. Detrital zircons in three metapsammitic samples (composite group of 240 grains) yielded prominent age population peaks at ∼1090, ∼96…
Current Wildland Fire Patterns and Challenges in Europe: A Synthesis of National Perspectives
2021
Changes in climate, land use, and land management impact the occurrence and severity of wildland fires in many parts of the world. This is particularly evident in Europe, where ongoing changes in land use have strongly modified fire patterns over the last decades. Although satellite data by the European Forest Fire Information System provide large-scale wildland fire statistics across European countries, there is still a crucial need to collect and summarize in-depth local analysis and understanding of the wildland fire condition and associated challenges across Europe. This article aims to provide a general overview of the current wildland fire patterns and challenges as perceived by natio…
Population dynamics, social resilience strategies, and Adaptive Cycles in early farming societies of SW Central Europe
2017
Abstract Inferred European Holocene population size exhibits large fluctuations, particularly around the onset of farming. We attempt to find explanations for these fluctuations by employing the concept of cycling, especially that of the Adaptive Cycle. We base our analysis on chronologically and chorologically highly resolved ceramic and site data from the Linear Pottery culture (Germ. Linearbandkermik ) of the early Neolithic of southwestern Central Europe. Typological seriation with dendrochronological anchor dates provides the age model for these data. Ceramic motifs are analysed with respect to the temporally changing diversity in decoration. The temporal sequence of major decoration m…
Dyke failures in the Province of Groningen (Netherlands) associated with the 1717 Christmas flood: a reconstruction based on geoscientific field data…
2020
AbstractThe 1717 Christmas flood is one of the most catastrophic storm surges the Frisian coast (Netherlands and Germany) has ever experienced. With more than 13,700 casualties it is the last severe storm surge with a death toll of this order. At the same time, little is known about the hydrodynamic conditions and the morphological effects associated with this storm surge.In this study, 41 potential dyke failures in the Province of Groningen (Netherlands) associated with the 1717 Christmas flood were systematically reconstructed and mapped by using historical maps and literature and by analysing the recent topography in search of typical pothole structures and sediment fans. The dimensions …
Advances of sclerochronology research in the last decade
2021
Over the past decade, sclerochronological research has continued to develop rapidly and is diversifying with respect to methods, taxa, geographic coverage as well as temporal depth. Chonologically aligned environmental records from bivalves, gastropods, coralline algae, corals, and many other periodically formed biogenic hard parts are integrated to build networks across broad spatial domains and trophic levels. Replication and exact dating ensure that environmental signals are fully preserved and facilitate the integration among chronologies as well as observational records of climatic and biological phenomena. The proliferation of chronologies promises to usher in a new era of synthesis t…
A multi-proxy, diachronic and spatial perspective on the urban activities within an indigenous community in medieval Riga, Latvia
2017
Abstract The research presented here represents the first urban medieval context in Latvia where an integrated, multi-proxy environmental sampling strategy has been applied. The establishment of Riga, the modern capital of Latvia, is synonymous with the Livonian Crusade, and the foundation of the medieval town is examined here. This study uses an intra-site comparison of environmental datasets from several buildings to provide a unique, high resolution, diachronic analysis of the daily life of the inhabitants within the pre-Hansa town, and specifically of the indigenous ‘Liv’ population during the period of the Livonian crusades, 1198–1291. The integrated zooarchaeological, archaebotanical,…
Missing Records and Depositional Breaks in French Late Pleistocene Cave Sediments
1993
AbstractCave entrance and rock shelter infillings are positioned within the Pleistocene chronology for three areas of France (northern Alps, Franche-Comté, and Périgord). Despite minor local variations, it is possible to identify regional types with a consistent depositional record over long intervals of time. The interregional variability relates to the frequency and position of the gaps within the infillings. Sites in the northern Alps have not yielded any artifacts older than the Upper Paleolithic (Magdalenı́an), and dated sedimentary sequences do not go back beyond the Older Dryas. More complete sequences in Franche-Comté contain Mousterian industries. Two major gaps occur here, one las…
The ecogenetic link between demography and evolution: can we bridge the gap between theory and data?
2007
Calls to understand the links between ecology and evolution have been common for decades. Population dynamics, i.e. the demographic changes in populations, arise from life history decisions of individuals and thus are a product of selection, and selection, on the contrary, can be modified by such dynamical properties of the population as density and stability. It follows that generating predictions and testing them correctly requires considering this ecogenetic feedback loop whenever traits have demographic consequences, mediated via density dependence (or frequency dependence). This is not an easy challenge, and arguably theory has advanced at a greater pace than empirical research. Howeve…
« On-the-go » multispectral imaging system to characterize the development of vineyard foliage
2015
International audience; In Precision Viticulture, multispectral imaging systems are currently used in remote sensing for vineyard vigor characterization but few are employed in proximal sensing. This work presents the potential of a proximal multispectral imaging system mounted on a track-laying tractor equipped with a Greenseeker RT-100 to provide an NDVI index. The camera acquired visible and near-infrared images which were calibrated in reflectance. Vegetation indices were computed and compared to Greenseeker data. From two of the resulting datasets, a spatio-temporal study of foliage description through both optical systems is presented. This first study assessed the proximal imagery re…
Consistent response of bird populations to climate change on two continents
2016
Global climate change is a major threat to biodiversity. Large-scale analyses have generally focused on the impacts of climate change on the geographic ranges of species, and on phenology, the timing of ecological phenomena. Here, we use long-term monitoring of the abundance of breeding birds across Europe and the USA to produce, for both regions, composite population indices for two groups of species: those for which climate suitability has been either improving or declining since 1980. The ratio of these composite indices, the Climate Impact Indicator (CII), reflects the divergent fates of species favored or disadvantaged by climate change. The trend in CII is positive and similar in the …