Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Watching over the Amazon forest by remote sensing

29.04.2003


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.


Examination of images recorded at different dates has allowed an assessment of the relative proportions of spontaneously cleared areas and the pioneer fronts driving the processes of deforestation attributable to small-scale clearances advanced at a rate of 0.2% per year in the Saint-Georges de l’Oyapock region between 1958 and 1988. Superposing aerial photographs taken at 40-year intervals shows ephemeral deforestation in certain places, and that fallowing had led to forest recolonization in some previously-cleared plots. However, the expansion of pioneer fronts in Brazil advanced at a rate of 1.2% per year between 1988 and 1998 on the site studied in the State of Paca (3), this time without apparent reforestation processes, the clearances appearing to be permanent.

Surveillance of the Amazon forest environment is therefore made possible by combined comparative analysis of images obtained using several different data acquisition systems (Landsat, Spot, radar, aerial photographs) and recorded at different dates. Because it takes into account the different spatial scales of deforestation in Amazonia, this remote-sensing approach is especially suitable for monitoring changes in the forest situation and the impact of human activity on this environment. Clearance for agriculture, spontaneous marginal urbanization, ORPAIILAGE and illegal forestry can be watched. The approach consequently promises to be valuable as an instrument for land-use assessment in French Guiana and could be an additional aid to forest management in the Amazon for regional cooperation schemes.

Marie-Lise Sabrie | alfa
Further information:
http://www.ird.fr

More articles from Ecology, The Environment and Conservation:

nachricht Species may appear deceptively resilient to climate change
24.11.2017 | University of California - Davis

nachricht Scientists team up on study to save endangered African penguins
16.11.2017 | Florida Atlantic University

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New proton record: Researchers measure magnetic moment with greatest possible precision

High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons

The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

IceCube experiment finds Earth can block high-energy particles from nuclear reactions

24.11.2017 | Physics and Astronomy

A 'half-hearted' solution to one-sided heart failure

24.11.2017 | Health and Medicine

Heidelberg Researchers Study Unique Underwater Stalactites

24.11.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>