Consistent Root Metabolic Signatures Associated with Carbon-Stock Variation Among Pinus massoniana Provenances

Standing-tree biomass carbon stock varies among tree provenances, but its root metabolic correlates remain incompletely characterized. Pinus massoniana is an important subtropical conifer in southern China, and identifying metabolic signatures associated with high carbon stock may provide insights into provenance-related carbon accumulation. We profiled root metabolites from 36 independently sampled trees (six trees per provenance) representing six P. massoniana provenances at a single common-garden site in July 2022. The provenances were classified using provenance-level mean estimated individual-tree carbon stock: SM and AY (high), SW and QJ (medium), and HF and SX (low). Untargeted LC–MS data were evaluated using multiple overlapping provenance contrasts, KEGG pathway mapping, and exploratory weighted correlation network analysis. Of 10,386 detected LC–MS features, 746 met the nominal directional-consensus screening rule, and 199 showed strictly ordered provenance-mean relative-abundance patterns across the three predefined classes; 189 of these followed high < medium < low. Network integration generated 12 exploratory chemical candidates requiring structural confirmation. These findings describe internally consistent root metabolic associations with estimated standing-tree carbon stock rather. Generalization beyond one site and sampling date requires independent validation.