Intensified human activities-ecology interaction in the Chinese Loess Plateau at least two millennia: Evidence from palynological analysis

Palynological analysis on the Chinese Loess Plateau (CLP), the cradle of Chinese civilization, is essential for exploring the complex relationships between human activities and ecological change during the Holocene. However, high resolution palynological analysis of loess deposits in this region remains limited. This study analyzed 98 fossil pollen and charcoal assemblages from the Linxia section in the western part of the CLP. The results show that from the Middle Holocene onwards, an increase in charcoal concentration and the presence of Hippophae and Brassicaceae marks the initial appearance of human activities, suggesting early settlers' engagement in agriculture and fire use. During the late Holocene, particularly around 2000 years ago, the sequential peaks of charcoal, Hippophae, and Brassicaceae concentrations indicate a significant intensification of human activities. This intensification is further supported by other records, such as grain size and fungal spore data. By integrating palynological data with other environmental proxies, this study provides a new perspective on the long-term ecological history of the CLP, shaped by the ongoing interaction between natural environments and human activities during the Holocene. The consistent timing of human impacts on vegetation across the CLP, especially the significant enhancement at least two millennia, provide key evidence for understanding the patterns and extent of human activities' influence on ecosystems.