Sand-fixing measures improve soil particle distribution and promote soil nutrient accumulation for desert - Yellow River coastal ecotone, China

In the fragile desert ecosystems of the world, sand-fixing measures play an irreplaceable part in ecological restoration. However, it is unclear how the long-term establishment of sand-fixing measures affects soil particle distribution and soil nutrients for the desert - Yellow River coastal ecotone. Therefore, we selected sand-fixing measures that have been established for fifteen years: Pinus sylvestris (PS), Populus alba (PA), Elaeagnus angustifolia (EA), Hedysarum scoparium (HS), Salix psammophila (SC), Salix psammophila checkerboard barriers (SCSB), and mobile sandy land (LS). We analyzed soil physical properties, chemical properties, soil fractal dimension (D), and multi-fractal parameters in the top soil layer (0-20 cm). The results showed that the establishment of sandfixing measures significantly increased the clay and silt, and decreased the sand (p < 0.05). Sand-fixing measures promote the heterogeneity of soil particle distribution and increase its dispersion. The soil nutrition content was significantly increased under different sand-fixing measures (p < 0.05), and soil organic carbon (SOC) and alkaline nitrogen (AN) changed significantly. The D value is between 2.18 and 2.39. The D value and multifractal parameters were driven by soil physicochemical properties and aboveground biomass (AGB). The regression model demonstrates a significant correlation between the D values and multi-fractal parameters (R-2 = 0.58-0.77, p < 0.001). Therefore, we suggest that multifractal parameters can replace the D values as indicators of soil environmental changes in desertification. This study complements the information on the restoration of soils in the desert-Yellow River coastal ecotone by sand-fixing measures. In addition, we suggest that desert ecological management should be tailored to regional environmental differences to establish an integrated model of restoration of sand-fixing measures in the future. The results of this study scientifically provide a theoretical basis for the future reconstruction of ecologically fragile areas.