Impacts of climate change on grassland fractional vegetation cover variation on the Tibetan Plateau

Climate change has profoundly impacted Tibetan Plateau grasslands, necessitating a comprehensive analysis of the historical and future responses across diverse grassland types, with the integration of an elevated atmospheric CO2 concentration (eCO2) and climatic factors. In this study, the response of the Tibetan Plateau grassland was investigated, with a focus on the fractional vegetation cover (FVC). By employing an enhanced ecohydrological model for the baseline (1985–2014) and future (2031–2070) periods under shared socioeconomic pathway (SSP) scenarios, the responses of FVC to climate change were predicted across all grassland types. The alpine steppe exhibited the most rapid growth, with average FVC increases projected to reach 37 ± 7 %–81 ± 15 % for alpine meadow, 82 ± 22 %–185 ± 55 % for alpine steppe, and 50 ± 8 %–95 ± 23 % for temperate grassland by the 2060s. During the baseline, eCO2 primarily caused the FVC increases in alpine meadow and temperate grassland, while warming governed alpine steppe growth. Interannual variability in the FVC of alpine grasslands was temperature-driven, while that of the temperate grasslands was driven by precipitation. An increase in the FVC of the alpine steppe was caused by warming under both low- and high-emissions scenarios. For the alpine meadow and temperate grasslands, precipitation was dominant for FVC changes in the SSP1–2.6 scenario, and eCO2 was dominant in the SSP3–7.0 and SSP5–8.5 scenarios. These findings provide a vital foundation for grassland management, carbon cycling comprehension, and vegetation feedback estimations on the Tibetan Plateau.