Climate change was more important than human activity in late Holocene vegetation change on the southern Tibetan Plateau

The Tibetan Plateau (TP) is one of the world's largest alpine grassland ecosystems, and it has been influenced by both climate change and human activities during the late Holocene. However, the dominant driver of vegetation change in these grasslands, whether climate change or human activity, remains controversial, particularly on the southern Tibetan Plateau (STP). Here, we present a high-resolution phytolith record from the STP, which reveals the relatively stable long-term grassland composition during the past ∼3,600 years. In addition, we used Structural Equation Modeling (SEM) to investigate the relative importance of seven potential drivers of grassland change on the STP over the past ∼3,600 years: precipitation, temperature, atmospheric CO₂ concentration, fire, human influence index (HII), cultivation and pastoralism activity. The results indicate that precipitation was the most important driver of changes in grassland composition, whereas the effect of human activities was limited. While our findings highlight the significant role of climate change in driving changes in alpine grassland composition, the increasing influence of human activities should be considered in future assessments.