ABSTRACT The soil nutrient status in riparian zones, which are transitional areas between aquatic and terrestrial ecosystems, is highly dynamic and plays a crucial role in the health of aquatic ecosystems. However, the mechanisms underlying nutrient changes in these zones remain unclear and vary across studies. This study employed spatial distribution analysis, linear regression, Pearson's correlation, redundancy analysis (RDA), random forest analysis and partial least squares path modelling analysis (PLS–PM) to investigate the horizontal and vertical variations in soil nitrogen and phosphorus, as well as the regulatory roles of topography, hydrology and plants in soil nutrient changes in the riparian zones of Dongjiang Lake. The results showed clear stratification of soil nutrients, with nitrogen and phosphorus concentrations in the 0–20‐cm soil layer generally higher than those in the 20–40‐cm soil layer. Random forest analysis indicated that the key factors influencing nitrogen were flooding duration, flooding height and the digital elevation model (DEM), while phosphorus was mainly affected by plant factors (Shannon–Wiener index, Simpson index, density, coverage and biomass), distance from the mountain to plots, DEM and flooding duration. PLS–PM analysis revealed that soil nitrogen and phosphorus were shaped not only by the direct effects of topography, hydrology and plants but also by the indirect effects of hydrology mediated by topography. Furthermore, soil nitrogen in riparian zones was co‐regulated by plant and hydrological factors, whereas soil phosphorus was co‐regulated by topographic and plant factors. Compared with nitrogen, phosphorus exhibited greater instability. This mechanistic understanding of soil nutrient dynamics provides a scientific basis for nutrient control, management and ecological restoration in riparian zones.
zhang et al. (Thu,) studied this question.