Gold-rush in a forested El Dorado: long-term assessment of deforestation and policy issues

Small-scale gold-mining has been the major driver of last decade deforestation within the Guiana Shield, one of the least degraded tropical forests in the world. Its social and environmental impacts are diverse and severe: water pollution due to turbidity and mercury, over-hunting in remote and preserved areas, insecurity, prostitution or malaria expansion. Deforestation is another direct effect of small-scale gold-mining, being also the easiest way of assessing its expansion. Using deforestation maps produced by Hansen et al. (2013) and additional Landsat based dataset during the 90's, we provide a long term assessment of deforestation due to small-scale gold-mining between 1990 and 2014 in the Guiana Shield. Quasi-annual measurements of deforestation over the whole region show a very strong exponential relationship between deforestation due to small-scale gold-mining and gold-prices, explaining its massive increase until years 2012-13, when both prices and deforestation started to drop. This highly dynamic relationship suggests low level of governance at the regional scale and raises the question of the ability of local countries to efficiently limit their level of deforestation in eventual REDD+ like projects. A focus on each country's situation shows very different temporal patterns of deforestation between French Guiana and both Suriname and Guyana. While deforestation in the two last countries follows gold prices from the beginning until the end of the period; small-scale gold-mining activity in French Guiana seems to be sharply increasing until 2004. Then, the pressure of military interventions against illegal mining, helped by a regular monitoring using remote sensing techniques (Mining Activity Observatory managed by the French Forest Service), probably overcomes the price effect. Studying the efficiency of local policy in reducing deforestation and associated carbon emissions is of major importance to assess the ratio between economic costs and environmental benefits of such interventions. Looking at potential deforestation leakages between countries as a response to local management is also a necessity to improve environmental governance at the regional scale. (Texte intégral