Complex spatiotemporal heterogeneity in Holocene human activities revealed by pollen and Pb records from major monsoonal China

Human activities have had significant impacts on the natural environment and the concept of Anthropocene sparked many debates during the Holocene. Extensive research has been conducted in investigating past human activities by using multi-proxies in geological archives. However, previous research has normally focused on analyzing the human activity with limited proxy records and lacks integrated studies utilizing multiple types of proxies within the same region. Through multi-proxy analysis of pollen and heavy metal records from 24 sites across Southern, Northern, and Southwestern China, this study reveals the spatiotemporal variations in human activities and different responses of proxies to human activities. The results indicate that: (i) the integrated Z-Score results of pollen and Pb suggest the spatial differences in the history of human activities, with Southern China experiencing the earliest anthropogenic influence, followed by Northern and Southwestern China. (ii) different proxies exhibit varying responses to human activities, with pollen records typically responding earlier than heavy metal records, due to the different inherent characteristics of proxies and historical stages of human activities. (iii) there are also temporal differences in altitude for human activities indicated by different proxies. Human activities of the same type mainly occur in low-altitude areas and then spread to high-altitude areas. Therefore, it is essential to utilize multi-proxy in various geological archives to reconstruct a more comprehensive history of human activities and provides deeper insights into human-environment interactions.