Links Between Plant Functional Reorganization and a Soil Multifunctionality Proxy During Karst Forest Recovery

Whether vegetation structural recovery is accompanied by improvement in soil properties remains a key question for evaluating karst forest restoration. We investigated a six-stage natural recovery sequence in the Maolan karst forests of southwestern China by analyzing 18 plots. This sequence was interpreted as a spatial gradient rather than a strict temporal succession. Six soil physicochemical variables, community-weighted leaf traits, and functional diversity indices were integrated to construct a relative soil multifunctionality proxy (SMF) and to evaluate associations between soil-property patterns and plant functional reorganization. Later woody stages generally had lower soil bulk density and higher soil moisture, organic carbon, nitrogen, phosphorus, and potassium contents, and the SMF was higher from the tree–shrub stage onward. Community-weighted leaf traits showed nonlinear reorganization along the leaf economic spectrum, indicating shifts in resource acquisition and tissue investment strategies. Functional diversity responded asynchronously: functional richness was positively associated with the SMF, whereas dispersion-related indices did not show consistent positive associations. These findings indicate that variation in the SMF is associated with measured soil properties, the reorganization of dominant leaf traits along the leaf economic spectrum, and the restructuring of functional trait space, rather than being attributable to any single trait or diversity index. Because this study used 18 plots and a space-for-time design, the observed relationships should be interpreted as spatial associations, not temporal or causal effects.