[Spatiotemporal Evolution Patterns of Grassland Degradation and Its Driving Factors on the Loess Plateau].

The vegetation restoration strategies on the Loess Plateau are progressively orienting towards natural regeneration, utilizing grasslands for ecological recovery. However, there is a dearth of precise, in-depth quantification of the long-term spatio-temporal patterns and driving factors of grassland degradation in this area. This study, based on AVHRR and MODIS NDVI data, employs Google Earth Engine （GEE）, grassland degradation indices, and spatio-temporal analysis to examine the vegetation cover and degradation patterns of the Loess Plateau's grasslands from 1986 to 2021. The study reveals the influence of meteorological elements on grassland degradation, with specific findings as follows： ① Grasslands exhibited moderate degradation on the Loess Plateau, with a degradation area of 17.4×10⁴ km² （43.8% of the total grassland area） before 2000, characterized by a degradation index of 2.25. Post-2000, the degraded area reduced to 15.3×10⁴ km² （38.4% of the total）, with a degradation index of 2.06. ② Significant spatial heterogeneity in grassland degradation was observed, with pre-vegetation recovery （1986-2000） showing minimal overall change in the degradation index, with non-significant increases in the southeast and west （38% of the area） and decreases in the central and northwest （34% of the area）. Post-vegetation recovery （2001-2021）, the regional grassland degradation index showed an overall decrease and a constant trend （85% of the area）, especially in the eastern and southern parts of the region, while it showed an insignificant increase trend in the Mu Us region. ③ Meteorological elements, notably precipitation and relative humidity, were identified as the primary drivers of grassland degradation, accounting for 80% of the variance, with precipitation and relative humidity contributing 45.8% and 21.7%, respectively. These results provide a data-supported framework for evaluating the spatio-temporal evolution of the Loess Plateau's grassland ecosystem and inform scientific approaches to sustainable vegetation management in the region.