Analysis and management of ecological risks : interests of PRA.
Résumé
Increasing intensity of human activities and natural resources exploitation threaten Earth ecological stability and resource durability. The recent understanding of the stakes linked with biodiversity erosion, especially for the goods and services given back to the society, rises the need for tools able to tackle ecological risks analysis. Addressing such analyses leads to be able to apprehend the inherent complexity of the natural ecosystems functioning, the diversity of spatio-temporal scales and the diversity of the encountered hazards. In this current work, we show that the Preliminary Risk Analysis (PRA) methodology, recently updated by Desroches et al. (2009), suits well this problematic and allows to perform such global and systemic analyses of systems that are alive, multidimensional and multifunctional. The adapted methodology is illustrated by 2 examples at various organization levels: (i) an animal species, the Atlantic Salmon; (ii) an strongly anthropized system, the Forest of Landes. For each one, we performed the several steps of the PRA: (i) the PRA System which maps the hazardous situations as interactions between hazards and vulnerable elements of the studied system; (ii) the definition of likelihood and gravity scales and finally the referential for risk acceptability; (iii) the building of scenarios giving an initial and a residual risk quantified with the former elements; (iv) the mapping of the risks (Kiviat and Farmer diagrams) as a statistic and graphic synthetic view of the analyses. This tool shows a great potential for many ecological systems.
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