Knowledge of tropical and sub-tropical metallophyte distribution and ecology lies far behind that for temperate taxa, especially those in Europe. Few metal-tolerant and metal hyperaccumulator plants have been reported in Latin America in comparison to other areas of the world, such as North America, Oceania, Asia, Europe and Africa (Brooks 1998). A total of approximately 172 plant species have been described in the literature for the Region as either metal-tolerant (30 species) or hyperaccumulators (142 species; Ginocchio & Baker 2004), a very low number when compared to the high plant diversity described for the Region (Cincotta etal. 2000). Most of these plants are nickeltolerant and hyperaccumulator plants (89%) as most studies pertain to serpentine areas in Brazil, Cuba, Dominican Republic and Venezuela, followed by copper (5%) and arsenic (3%) (Baker & Brooks 1988; Ginocchio & Baker 2004). Investigations over ultramafic rocks in Argentina and Paraguay (Reeves & Baker 2000) have also been performed but they have not revealed further metal-tolerant plants.
Latin America is a potential area where metallophytes could be found, not only due to the high and unique plant diversity but also to the presence of a high number of ore deposits (e.g., gold, silver, copper, iron and lead) and metal-enriched areas such as those near abandoned tailings dumps and metal smelters, due to historical mining operations under no environmental regulations. Many areas in Latin America are major centres of plant diversity, not only because of species-rich tropical forests but also because of many geographical areas where a diverse and unique endemic flora exists. For example, 8 of the 25 hotspot areas defined for their high biodiversity in the world are located in Latin America (Myers et al. 2000). However, this diversity is still poorly evaluated, studied and protected, including metallophytes. If a high and unique plant diversity has co-existed and evolved in ore-rich environments, it is reasonable to think that metallophytes may have evolved in the Region, and thus, it is necessary to start reconnaissance work, before possible extinction from metal mining activities, notably strip-mining. Current information on metallophytes in the Region has derived from three main sources: scientific research performed by botanists and plant ecologists, geobotanical surveys performed by geologists and mine engineers and traditional knowledge from small-scale artesanal miners.
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