Areas deforested in Brazil increased from 152 000 km_ in 1976 to 517 000 km_ in 1996. That figure is the equivalent of the surface area of France. Deforestation is a complex process and involves a host of changing and widely differing situations. The factors behind it are many and varied. They include rising demand for agricultural land, international trade needs for timber and political decisions regarding strategic planning and development.
Researchers of the IRD Space Unit conducted an investigation from January 2000 to December 2002, on deforestation in the Amazon Basin. Their overall procedure is based on the use of remote-sensing data obtained from satellites and aircraft. The approach adopted, termed “descending hierarchical”, often used by geographers, was first applied in French Guiana. It consists in analysing the Amazonian forest cover making the most of a full range of remote-sensing tools which provide means of taking into account the different scales involved. These scales are: the regional scale, studied using satellite images of NOAA-AVHRR and Spot 4 VEGETATION sensors which give coverage of terrains of surface area of 2000 km_; the sub-regional scale, with Landsat and Spot images which provide more detailed data on areas of 185 and 60 km_ respectively; local scale (a few tens of kilometres square observed using aerial photography). Together these tools enabled the researchers were therefore able to demonstrate the size diversity of cleared plots in the Amazon forest, from extensive areas of deforestation like the pioneer fronts of Brazil to the small 1-ha plots epitomized by brushwood plots in French Guiana.
In parallel, the team processed a mass of field measurements and socio-economic data, for French Guiana in particular, in order to calibrate the available aerial or satellite observations, interpret them and place them in the prevailing context. Such socio-economic data take particular account of the land-ownership situation and strategic planning and redevelopment problems. The untimbered areas in Guiana correspond to spontaneous land-take for agriculture often liable to change rapidly and shift geographically, whereas the pioneer fronts in Brazil mark rather government intentions to enhance agricultural potential, expressed as a plan which indeed prompts the clearances and permanent occupation for pastoral purposes.
Marie-Lise Sabrie | alfa
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
21.09.2017 | Physics and Astronomy
21.09.2017 | Life Sciences
21.09.2017 | Health and Medicine