Resource availability reshapes clonal recovery and trait coordination across fragment configurations of Salvinia natans

Background Clonal aquatic plants can regenerate from fragments, but how light and nutrient availability influence recovery across fragment configurations remains poorly understood. We conducted a four-week factorial experiment with the floating fern Salvinia natans , combining two light levels, two nutrient levels and three configurations: light fragmentation (LF; two three-node fragments), moderate fragmentation (MF; three two-node fragments) and severe fragmentation (SF; six single-node fragments). Initial total node number was standardized across configurations, with five replicate pots per treatment combination. We measured growth, biomass allocation and frond-specific metabolism, and examined trait coordination using plant trait multilayer networks (PTMNs). Results Under high-light, nutrient-rich conditions, MF produced more frond pairs and ramets and accumulated more dry weight than LF or SF. Under low light, dry-weight accumulation remained low and differences among configurations narrowed. High light combined with low nutrients was associated with higher carbohydrate concentrations and a greater submerged-frond to floating-frond dry-weight ratio. PTMNs showed contrasting patterns of trait coordination: LF had the greatest cross-layer connectivity, MF the strongest local clustering, and SF the highest module interlayer association. Carbohydrate traits and biomass allocation occupied central network positions, with the leading hubs differing among configurations. Conclusions The growth advantage of MF depended on resource availability. Fragment configurations were also associated with distinct relationships among carbohydrate status, tissue allocation and clonal growth. These findings show that recovery responses differed in both growth performance and the coordination of traits across functional layers.