Abstract:

We conducted an in-depth analysis of reverse succession in degraded desert grasslands to identify its driving factors. A field experiment was conducted in degraded desert grasslands of Ningxia， and the changes in plant community characteristics， soil physicochemical properties， and their correlations under different forage reseeding configurations （a grass mixture P₁， a legume mixture P₂， and a grass-legume mixture P₃） were investigated. The effects of reseeding configurations on plant community structure and soil nutrient contents were also evaluated. The results show that forage reseeding of the degraded pasture increased the proportion of legumes in plant communities， and resulted in increased vegetation cover and increased values of Simpson’s， Shannon-Wiener’s， and Margalef’s indexes. Reseeding with the grass-legume mixture increased the aboveground biomass of the plant community. Reseeding with the grass mixture significantly reduced soil bulk density， and reseeding with either the grass mixture or the grass-legume mixture decreased soil electrical conductivity. All the reseeding treatments resulted in increased total phosphorus and potassium contents in the 0-10 cm and 10-20 cm soil layers， increased organic carbon and total nitrogen contents in the 0-10 cm soil layer， and increased pH in the 10-20 cm layer； and decreases in soil pH in the 0-10 cm soil layer and organic carbon content in the 10-20 cm soil layer. The organic carbon and total nitrogen contents in the 0-10 cm soil layer showed positive correlations with plant community diversity indexes （Simpson’s， Shannon-Wiener’s， and Margalef’s indices）. Key factors driving vegetation restoration included organic carbon and total phosphorus contents in surface soil （0-10 cm）， along with pH and total phosphorus content in the subsurface soil layer （10-20 cm）. The grass-legume mixed configuration demonstrated optimal performance in enhancing grassland productivity， improving plant communities， and optimizing the soil nutrient profile. Therefore， reseeding with a grass-legume mixture is the preferred approach for restoration of degraded desert grasslands.

Key words: desert grassland, forage reseeding, plant community characteristics, soil physical and chemical properties