Stoichiometric characteristics and environmental drivers of soil in estuarine delta wetlands: a case study of the Yellow River Delta

Estuarine delta wetlands are relatively fragile ecosystems, and soil ecological stoichiometry plays an important role in understanding wetland ecological conditions and developing effective restoration and sustainable management strategies. However, the spatial patterns of soil ecological stoichiometric characteristics and their relationships with environmental factors in estuarine delta wetlands remain insufficiently understood. In this study, we investigated soil physicochemical properties and ecological stoichiometric ratios (ESR) across gradients of soil salinity (Sa), bulk density (BD), and distance to shoreline (DTS) in the Yellow River Delta (YRD) wetland, and explored their associations with environmental factors. The results showed that soil physicochemical properties and ESR exhibited significant spatial heterogeneity. With increasing soil salinity, the contents of total carbon (TC), total nitrogen (TN), and total phosphorus (TP) significantly decreased, whereas the C:N ratio increased and the C:P and N:P ratios decreased ( P < 0.05). With increasing soil bulk density, TC and TN contents significantly declined, accompanied by an increase in C:N and decreases in C:P and N:P ratios ( P < 0.05). Along the DTS gradient, soil nutrient contents increased, C:N decreased, and N:P increased. Nearshore soils exhibited a “low nutrient-high stoichiometric ratio” pattern, whereas offshore soils showed a “high nutrient-low stoichiometric ratio” pattern. C and N contents were identified as important factors associated with variations in soil ecological stoichiometry along the DTS gradient. SEM further revealed significant associations between soil environmental factors and ecological stoichiometric characteristics, indicating that environmental gradients were closely linked to the spatial variation in soil ecological stoichiometry across the YRD wetland. This study elucidates the spatial variability of soil ecological stoichiometric characteristics and their relationships with environmental factors in the YRD wetland, providing scientific support for soil assessment, ecological restoration, and sustainable management of estuarine delta wetlands.