Differentiation of plant adaptive strategies on the Jingpo Lake lava plateau: a comparison of leaf and absorptive root functional trait spectra across different life forms

Focusing on the highly heterogeneous habitat of the Jingpo Lake lava plateau, this study quantified 24 above- and below-ground functional traits across 12 dominant species. Transcending the conventional single-organ perspective, we investigated whether environmental stress drives the divergence of adaptive strategies by amplifying trait variation among distinct life forms. Woody plants exhibited substantially higher phenotypic plasticity than herbaceous species, with the average coefficient of variation for absorptive roots reaching 32.74% – approximately twice that of herbs. Reflecting a ‘structural reinforcement’ strategy, the main vein thickness (MV) and root stele diameter (RSD) of woody plants were 1.79 and 2.22 times greater than those of herbs (P < 0.05), respectively. Core above- and below-ground anatomical traits in woody plants were highly positively correlated (P < 0.01), indicating strong ‘functional integration.’ Conversely, herbaceous plants lacked significant cross-organ structural correlations (P > 0.05) and displayed clear ‘trait decoupling,’ relying primarily on ‘phenological escape’ and significantly elevated mycorrhizal colonization rates (MIs) for resource acquisition. Principal component analysis demonstrated that the first axis captured 48.7% of the total variation, driven predominantly by below-ground traits such as root diameter, with significant differences observed between life forms (P < 0.05). This underscores that below-ground traits explain the strategic divergence of plant functional groups in lava plateau habitats more effectively than above-ground traits. Ultimately, our results validate the hypotheses that extreme habitats amplify resource trade-offs between woody and herbaceous plants, and that below-ground traits act as robust indicators of strategy divergence, offering essential scientific insights into plant survival and adaptation mechanisms in fragile ecosystems.