Ecosystem, forest type distribution

The receptors of interest are soils of agricultural (arable lands, grasslands) and non-agricultural (forests, steppes, heath lands, savanna, etc.) ecosystems. In non-agricultural ecosystems, the atmospheric deposition is the only input of heavy metals. Regarding the Forest ecosystems, a distinction should at least be made between Coniferous and Deciduous Forest ecosystems. When detailed information on the areal distribution of various tree species (e.g., pine, fir, spruce, oak, beech and birch) is available, this should be used since tree species influence the deposition and uptake of heavy metals and the precipitation excess. On a world scale, soil types can be best distinguished on the basis of the FAO-UNESCO Soil Map of the World, climate and ecosystem data from NASA database (1989). 

These species are distributed over five main types of biomas the cerrado savannahs, the Mata Atlantica rain forest, the Amazon forest, pantanal wetlands, and caatinga semiarid scrublands, as can be seen in Fig. (1). In spite of all this wealth, the first two are among the ecosystems regarded as hotspots in South America [5]. 

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