Mires and Histosols in French Guiana (South America): new data relating to location and area

Large peatland areas have been identified in French Guiana, an equatorial province (département) of France, but the exact distribution and ecological condition of mires is not well known. Maps of pedological and agronomic units that were prepared between the early 1950s and 1975 enable us to improve on previously published estimates of Histosol areas in French Guiana. Only the non-forested parts of the province have been studied because there are hardly any pedological maps for the portion that lies within the Amazon rainforest. The extent of Histosols recorded in French Guiana is around 975 km2, which is 57–60 % of the estimates of peatland area (1620 km2 and 1720 km2) reported in the scientific literature. The largest Histosol areas are located near the coast in the north-east of the province, between Cayenne and the border with Brazil. This region receives the highest annual rainfall recorded in French Guiana and provides a particularly favourable hydro-geomorphological setting for peat formation. It will be necessary to explore these large Histosol areas in order to characterise them and to study the associated mire vegetation. Difficult access, combined with the adverse hydro-climatic conditions, will make this a long-term endeavour.