Variations in root functional traits facilitate the adaptation of pioneer plants to rare earth element mine tailings

Abstract The trade‐offs in plant root traits significantly influence the adaptation and community dynamics in heterogeneous habitats. However, the role of inter‐ and intraspecific root trait variation in the adaptation of pioneer plants in stressed mine tailings is poorly understood. We assessed root morphological and chemical traits of 16 dominant species from unexploited forest sites adjacent to rare earth elements (REEs) mine tailings, and three pioneer species ( Miscanthus sinensis , Dicranopteris linearis and Pinus massoniana ) across a gradient of soil stress—including REEs toxicity, nutrient deficiency and compaction—from forest to REEs tailings. In the two‐dimensional root economics space (RES), the contents of cellulose, hemicellulose and silicon were coaxial with the collaboration gradients (‘do‐it‐yourself’–‘outsourcing’) and inversely related to fine root diameter. Meanwhile, root REEs content aligned with conservation gradients (‘fast’–‘slow’), indicating a slow strategy. Interspecific variations did not show a distinct strategy preference for pioneer species compared with non‐pioneer plants. However, notable intraspecific variations were observed, particularly in stress‐related traits, such as root N content, C:N ratio and REEs content, which exceeded interspecific variations. All three pioneer species exhibited a shift towards ‘slow’ strategies, while P. massoniana also transitioned towards ‘do‐it‐yourself’ strategies, driven by increased soil bulk density, elevated bioavailable REEs content, and reduced soil carbon and nutrient levels in the tailings. Synthesis and applications . Our findings highlight the pivotal role of root chemical traits and intraspecific plasticity in facilitating the adaptation of pioneer plants to extreme REE tailing environments. The observed shifts towards stress‐tolerant ‘slow’ strategies and ‘do‐it‐yourself’ nutrient acquisition provide a trait‐based framework for advancing phytoremediation in the ecological restoration of degraded mine tailings, such as informing plant species selection.