Search results for "Global Change"
showing 10 items of 639 documents
Timing and patterns of the ENSO signal in Africa over the last 30 years: insights from normalized difference vegetation index data.
2014
Abstract A more complete picture of the timing and patterns of the ENSO signal during the seasonal cycle for the whole of Africa over the three last decades is provided using the normalized difference vegetation index (NDVI). Indeed, NDVI has a higher spatial resolution and is more frequently updated than in situ climate databases, and highlights the impact of ENSO on vegetation dynamics as a combined result of ENSO on rainfall, solar radiation, and temperature. The month-by-month NDVI–Niño-3.4 correlation patterns evolve as follows. From July to September, negative correlations are observed over the Sahel, the Gulf of Guinea coast, and regions from the northern Democratic Republic of Congo…
Deep-rooted “thick skinned” model for the High Atlas Mountains (Morocco). Implications for the structural inheritance of the southern Tethys passive …
2006
A re-interpretation of the deep structure of the High Atlas is presented through integration of geophysical and geological data, highlighting the architectural significance of the southern Tethys palaeomargin. Previous crustal models suggest the occurrence of a flat intra-crustal detachment at a depth of � 20 km, a zone where surface thrusts merge and below which the lower High Atlas crust appears continuous. However, within this study seismic refraction data, electrical resistivity surveys and gravity modelling all appear to detect a jump in crustal thickness between the High Atlas and the northern plains. We interpret these data as penetration by thrusts within the ‘‘South-Atlasic fault’’…
Jurassic architectural model of the southern Tethys Palaeomargin as deduced from Cenozoic geodynamic evolution of the High Atlas Mountains of Morocco.
2006
40 pages; International audience
Early Warning Systems for Food Security in West Africa: Evolution, Achievements and Challenges
2010
In West Africa, early warning systems (EWSs) for food security have been widely recognized to have contributed, in the last 20 years, to an improved ability to deal with famine emergencies. Nevertheless, despite the advancements in understanding of the environmental and socio-economic dynamics and despite the improved technologies, tackling food security remains a difficult task for decision makers as demonstrated by local food crises in many countries of the region. African Monsoon Multidisciplinary Analysis, while improving the understanding of the monsoon system, allowed us to better orient research challenges to provide EWS with improved products, effectively meeting the needs of end-us…
Home advantage? Decomposition across the freshwater-estuarine transition zone varies with litter origin and local salinity
2015
Expected increases in the frequency and intensity of storm surges and river flooding may greatly affect the relative salinity of estuarine environments over the coming decades. In this experiment we used detritus from three contrasting environments (marine Fucus vesiculosus; estuarine Spartina anglica; terrestrial Quercus robur) to test the prediction that the decomposition of the different types of litter would be highest in the environment with which they are associated. Patterns of decomposition broadly fitted our prediction: Quercus detritus decomposed more rapidly in freshwater compared with saline conditions while Fucus showed the opposite trend; Spartina showed an intermediate respon…
Seismic velocity structures of Southern Italy from tomographic imaging of the Ionian slab and petrological inferences.
2012
International audience; In this study we have determined detailed Vp and Vs seismic velocity models of the Ionian lithosphere subducting beneath the Tyrrhenian basin and of the surrounding mantle, by applying a post-processing technique to a large sample of local earthquake tomography studies. Our seismic velocity models permit us to infer the presence of low velocity anomalies within the slab, which we interpret as regions that are partially hydrated by fluids released during the subduction process. A petrological interpretation of the velocity anomalies gives new details on the magmatism of the volcanic Aeolian arc. Furthermore our velocity models provide a more detailed description of th…
Dinamica del C labile in suoli forestali simulando l'impatto da incendio ed il successivo spegnimento con acqua marina
2009
Obiettivo del presente lavoro è stato quello di valutare, in diversi suoli forestali ed a condizioni controllate di laboratorio, l’impatto del riscaldamento da incendio e del successivo spegnimento con acqua marina sulla dinamica del C estraibile e sulla cinetica di respirazione. A tal fine, in un’area pedoclimatica omogenea, sono stati selezionati 4 suoli sotto diverse essenze forestali: Eucalyptus camaldulensis (EC), E. occidentalis (EO), Pinus halepensis (PH) e Cupressus sempervirens (CS). I campioni di suolo sono stati riscaldati a 25 (controllo), 160 e 380 °C per 30 minuti ed umidificati al 50% della capacità idrica di campo con acqua marina o distillata (controllo), ottenendo così 6 d…
Altered epiphyte community and sea urchin diet in Posidonia oceanica meadows in the vicinity of volcanic CO2 vents
2017
Ocean acidification (OA) predicted for 2100 is expected to shift seagrass epiphyte communities towards the dominance of more tolerant non-calcifying taxa. However, little is known about the indirect effects of such changes on food provision to key seagrass consumers. We found that epiphyte communities of the seagrass Posidonia oceanica in two naturally acidified sites (i.e. north and south sides of a volcanic CO2 vent) and in a control site away from the vent at the Ischia Island (NW Mediterranean Sea) significantly differed in composition and abundance. Such differences involved a higher abundance of non-calcareous crustose brown algae and a decline of calcifying polychaetes in both acidif…