Search results for "Life on Land"
showing 10 items of 1478 documents
Holocene fire activity during low-natural flammability periods reveals scale-dependent cultural human-fire relationships in Europe
2018
Abstract Fire is a natural component of global biogeochemical cycles and closely related to changes in human land use. Whereas climate-fuel relationships seem to drive both global and subcontinental fire regimes, human-induced fires are prominent mainly on a local scale. Furthermore, the basic assumption that relates humans and fire regimes in terms of population densities, suggesting that few human-induced fires should occur in periods and areas of low population density, is currently debated. Here, we analyze human-fire relationships throughout the Holocene and discuss how and to what extent human-driven fires affected the landscape transformation in the Central European Lowlands (CEL). W…
Neolithic Human Societies and Woodlands in the North-Western Mediterranean Region: Wood and Charcoal Analysis
2017
An overview of woodland history in the north-western Mediterranean region, based on charcoal analysis (Anthracology) from Mesolithic and Neolithic sites, is proposed for the Mediterranean areas of France, Spain and Portugal. The taxonomic identification of charcoal fragments and the diachronic variations of taxa frequencies provide, for each settlement, an accurate image of the local vegetal cover. During the end of the last glaciation, beginning of the Holocene, vegetation dynamics reflects the evolution of climatic and geographic conditions. Any potential ecological impact by hunter-fisher-gatherer communities (Mesolithic) remains invisible; the same comment applies to the farming-herding…
Straw mulch as a sustainable solution to decrease runoff and erosion in glyphosate-treated clementine plantations in Eastern Spain. An assessment usi…
2019
[EN] In many Mediterranean areas, citrus orchards exhibit high soil loss rates because of the expansion of drip irrigation that allows cultivation on sloping terrain and the widespread use of glyphosate. To mitigate these non-sustainable soil losses, straw mulch could be applied as an efficient solution but this has been poorly studied. Therefore, the main goal of this paper was to assess the use of straw mulch as a tool to reduce soil losses in clementine plantations, which can be considered representative of a typical Mediterranean citrus orchard. A total of 40 rainfall simulation experiments were carried out on 20 pairs of neighbouring bare and mulched plots. Each experiment involved app…
Soils as a key component of the critical zone 6 : ecology
2018
Prod 2018-76h équipe EA SPE BIOME INRA AGROSUP; International audience
Loss in microbial diversity affects nitrogen cycling in soil
2013
International audience; Microbial communities have a central role in ecosystem processes by driving the Earth's biogeochemical cycles. However, the importance of microbial diversity for ecosystem functioning is still debated. Here, we experimentally manipulated the soil microbial community using a dilution approach to analyze the functional consequences of diversity loss. A trait-centered approach was embraced using the denitrifiers as model guild due to their role in nitrogen cycling, a major ecosystem service. How various diversity metrics related to richness, eveness and phylogenetic diversity of the soil denitrifier community were affected by the removal experiment was assessed by 454 s…
Impact of Manaus City on the Amazon Green Ocean atmosphere: ozone production, precursor sensitivity and aerosol load
2010
As a contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Cooperative LBA Airborne Regional Experiment (LBA-CLAIRE-2001) field campaign in the heart of the Amazon Basin, we analyzed the temporal and spatial dynamics of the urban plume of Manaus City during the wet-to-dry season transition period in July 2001. During the flights, we performed vertical stacks of crosswind transects in the urban outflow downwind of Manaus City, measuring a comprehensive set of trace constituents including O<sub>3</sub>, NO, NO<sub>2</sub>, CO, VOC, CO<sub>2</sub>, and H<sub>2</sub>O. Aerosol loads were characterized by concentrations of t…
Millennial-scale terrestrial ecosystem responses to Upper Pleistocene climatic changes: 4D-reconstruction of the Schwalbenberg Loess-Palaeosol-Sequen…
2021
Abstract Loess-Palaeosol-Sequences (LPS) in the Central European region provide outstanding terrestrial polygenetic and multiphase archives responding to past climate and environments over various spatial and temporal scales. As yet, however, the geomorphological and pedogenic processes involved in LPS formation, and their interplay with changes in ecological conditions, impede robust correlation with other palaeoenvironmental archives. The Schwalbenberg LPS, which drape a hillslope in the Middle Rhine Valley in western Central Europe, provide unique high-resolution records highly suitable for investigating the processes involved in their formation and the relationship to climatic influence…
Small-scale mixing processes enhancing troposphere-to-stratosphere transport by pyro-cumulonimbus storms
2007
Abstract. Deep convection induced by large forest fires is an efficient mechanism for transport of aerosol particles and trace gases into the upper troposphere and lower stratosphere (UT/LS). For many pyro-cumulonimbus clouds (pyroCbs) as well as other cases of severe convection without fire forcing, radiometric observations of cloud tops in the thermal infrared (IR) reveal characteristic structures, featuring a region of relatively high brightness temperatures (warm center) surrounded by a U-shaped region of low brightness temperatures. We performed a numerical simulation of a specific case study of pyroCb using a non-hydrostatic cloud resolving model with a two-moment cloud microphysics p…
Cambrian–Ordovician magmatism of the Ikh-Mongol Arc System exemplified by the Khantaishir Magmatic Complex (Lake Zone, south–central Mongolia)
2018
Abstract The Khantaishir Magmatic Complex (KMC) (south–central Mongolia) exposes a section of a magmatic system consisting of deep crustal, ultramafic cumulates (coarse-grained Amp gabbros and hornblendites; c. 0.35–0.5 GPa) to shallower crustal levels dominated by Amp–Bt tonalites ( c. 0.1–0.2 GPa). The magmatic rocks were emplaced during most of the Cambrian ( c. 538–495 Ma) and are mostly geochemically primitive (Mg# ~ 50), Na-rich and metaluminous. The (normal-) calc-alkaline signature and characteristic trace-element enrichment in hydrous-fluid mobile large-ion lithophile elements (LILE) relative to high-field strength elements (HFSE) suggest an origin within a magmatic arc. Multiple i…
Carbonated Inheritance in the Eastern Tibetan Lithospheric Mantle: Petrological Evidences and Geodynamic Implications
2020
International audience; The timing and mechanism of formation of the Tibet Plateau remain elusive, and even the present-day structure of the Tibetan lithosphere is hardly resolved, due to conflicting interpretations of the geophysical data. We show here that significant advances in our understanding of this orogeny could be achieved through a better assessment of the composition and rheological properties of the deepest parts of the Tibetan lithosphere, leading in particular to a reinterpretation of the global tomographic cross sections. We report mantle phlogopite xenocrysts and carbonate-bearing ultramafic cumulates preserved in Eocene potassic rocks from the Eastern Qiangtang terrane, wh…