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Summary of Proposal LAN1429

Title Synergistic use of very high resolution optical and TerraSAR-X data for studying ecological corridors
Investigator Corgne, Samuel - LETG Rennes COSTEL UMR 6554 CNRS, Geography
Team Member
Director Baudry, Jacques - INRA SAD-PAYSAGE, INRA
Professor Mercier, Grégoire - CNRS UMR 2872 TAMCIC, Institut National des Télécommunications
Professor Pottier, Eric - UMR CNRS 6164, IETR
Professor Hubert-Moy, Laurence - LETG Rennes UMR 6554 CNRS, Geography
Director Burel, Françoise - UMR CNRS ECOBIO, Biodiversity
Associate professor Corgne, Samuel - LETG Rennes UMR 6554 CNRS, Geography

Habitat fragmentation is considered as one of the most serious threats to biodiversity and a major cause of the current extinction crisis. In fragmented landscapes,movement is a key process for the survival of fauna and flora populations;easier the movement is better is the connectivity. Among the elements that increase landscape connectivity, corridors are particularly interesting and effective. Many national and international policies take into account the role of the ecological corridors in the biodiversity protection. Thus, ecological corridors are often considered as a management tool in land use planning and development policies. While the environmental reservoirs are quite well-known, it appears still necessary to identify and characterize ecological corridors.

Optical images are commonly used to identify and characterize ecosystems. Untilnow, ecological corridors were mostly mapped at coarse scales, through the detection of forested areas from image satellite medium or high spatial resolution. Thin corridors like wooded hedgerows surrounded by grassland which are not taken into consideration from these remotely sensed data have yet to be identified as they connect habitats that attract dispersing individuals. The identification of such a corridor requires determining local and intra annual changesin vegetation structure and composition. Even if optical data provide interesting information on land cover and land use at a local scale, their use is limited to cloudless periods. In addition, they provide information only on the surface of vegetation, the depth of penetration being very low in these wavelengths.

For these reasons, it is not possible to precisely determine soil moisture, map detailed vegetation and identify agricultural practices in ecological corridors in using only optical data. Moreover, radar images are under-used despite their relevance for the assessment of surface water, soil moisture, and characterization of vegetation structure, especially in regions where cloud cover is high. Furthermore, if the spatial resolution of radar images was until now not suited to study ecological corridors at a local scale, very high spatial resolution radar data such as TerraSAR-X images in fine and polarimetric modes have a strong potential to that end.

Thus, the synergetic use of radar andoptical satellite data is very promising. The fusion of optical and radar datasets will lead to a significant improvement of the derived data products and information on ecological corridors at local scales.

The general bjective of this project is to evaluate the complementarily of radar and optical data at very high spatial resolution for studying ecological corridors.

The methodological approach includes :
- Application of physical parameter inversion algorithms for pre-classification procedure,
- Investigation of the applicability of the time series Terra-SAR X data processing technique for vegetation and land-use monitoring,
- Assessment of the potential impact of High Resolution (fine mode) in dual pol for vegetation and land-use evolution analysis,
- Investigation of multisource data fusion between optical and radar imagery: methodological development (comparaison of Dempster-Shafer and Dezert-Smarandache methods),
- Study of the functionality of the ecological corridors mapped using for two different fauna models.

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