Background and aims <p>Phytostabilization of semiarid mine tailings involves establishing vegetation to reduce metal(loid) fluxes. Beyond biomass production and metal(loid) uptake, assessing ecophysiological traits is critical for selecting suitable species. This study examined six semiarid species (four shrubs, two conifers) in an 18&#xa0;months field-scale tailing phytomanagement project using an organic amendment combining biochar and municipal organic waste.</p> Methods <p>Plant responses were evaluated in amended and unamended plots by measuring biomass (above- and belowground), foliar metal(loid) concentrations (As, Cd, Cu, Mn, Pb, Zn), nutrient content (N, P, K), and isotopic signatures (δ¹³C, δ¹⁵N, δ¹⁸O).</p> Results <p>Amended plots showed improved soil fertility, including a threefold increase in total N and tenfold increase in organic carbon. Up to five species in amended plots exhibited higher biomass. Foliar metal(loid) concentrations varied by species and element. While P deficiency was alleviated, foliar N concentrations did not increase despite higher soil N. Enhanced P uptake was linked to higher δ¹³C values, suggesting improved water-use efficiency. Among C3 species, isotopic indicators revealed contrasting water-use strategies. The conifers (<i>Pinus halepensis</i> and <i>Tetraclinis articulata</i>) showed conservative traits, with lower stomatal conductance and higher WUE. <i>Tetraclinis articulata</i> in amended plots exhibited tighter water regulation, reflected by reduced foliar Ca and elevated δ¹⁸O. In contrast, shrubs (<i>Dorycnium pentaphyllum</i><i>, </i><i>Maytenus senegalensis</i><i>, </i><i>Rhamnus lycioides</i>) displayed more spendthrift strategies, characterized by higher transpiration and foliar N content.</p> Conclusions <p>The contrasting water and nutrient acquisition strategies suggests that not all species respond equally to amendments, emphasizing the need for species-specific approaches in successful phytostabilization.</p>