Heavy metal accumulation in Acacia spp. tissues across forest and tin mine reclamation sites of different ages

Abstract Post-mining landscapes in tropical regions suffer from degraded microclimates, infertile soils, and heavy-metal contamination. This study evaluated reclamation outcomes in Bangka Island, Indonesia, by analyzing microclimatic conditions, soil physicochemical properties, and heavy-metal dynamics in soils and Acacia across a recently reclaimed site (RT), a site reclaimed for more than five years (RG), and natural forest (HN) as reference. Results showed that microclimates became progressively moderated and soil fertility improved with reclamation age, although RT remained very acidic and nutrient-poor. Toxic metals (Pb, Sn, As, Cd) persisted above critical thresholds in RT and RG soils, but Acacia restricted their translocation (TF < 1), functioning as a phytostabilizer, while Zn was effectively extracted to aerial tissues (TF > 1). Reclamation has initiated recovery but remains incomplete. Integrated strategies combining Acacia with soil amendments, species diversification, and long-term monitoring are essential to achieve stable and resilient ecosystems comparable to natural forests.