Organ-specific nutritional divergence in reed under rotational grazing: Leaf quality optimization vs. stem functional enhancement in salinized meadows

Dominant species traits drive grassland productivity under grazing management. Phragmites australis (reed), a key species in salinized meadows, optimizes community productivity through grazing-mediated reorganization of leaf and stem functional traits—a previously unexplored mechanism in saline ecosystems. We compared continuous grazing (C1.33), rotational grazing (three stocking rates: R0.66, R1.33, R2.66), and no grazing (NG) over two years to assess how grazing system reconfigure this functional dichotomy. Grazing significantly influenced functional traits and aboveground biomass of reed (AGBR) ( P < 0.05). Rotational grazing induced organ-specific nutritional divergence: R1.33 optimized stem nutritional quality to enhance structural support, whereas R0.66 maximized leaf nutritional quality to improve photosynthetic efficiency. Path analysis revealed the crude protein (CP) content of reed leaves exerted the strongest direct effect on community CP (path coefficient = -60%), while stocking rate served as the dominant indirect driver (64% contribution). Among climatic factors, UV intensity (path coefficient = -0.37) and wind speed (path coefficient = -0.18) directly suppressed AGBR. The increase in stem-to-leaf ratio elevated crude protein in reed stem and leaves but reduced community CP and increased community acid detergent fiber. These findings demonstrate that rotational grazing optimizes the functional relationship between reed organs and grassland output through a “leaf quality priority, stem structural support” strategy, highlighting how management decisions directly influence dominant species performance and community productivity. This provides a novel framework for designing grazing strategies that synergistically enhance productivity and nutrient quality in saline grasslands globally. • Leaf number is the key trait regulating dominant species biomass response to grazing. • Rotational grazing drives organ-specific optimization: medium grazing (R1.33) enhances stem quality, while light grazing (R0.66) maximizes leaf quality. • Stem-to-leaf ratio increases organ-level crude protein but decreases community-level crude protein. • Stocking rate is the primary indirect driver of overall forage quality by mediating plant functional traits.