Dynamic Evolution of Vegetation and Its Driving Mechanism in the Qinling Region since the Last Glacial Maximum

Key words: 
• biomes /
• vegetation diversity /
• climate /
• fire activity /
• Last Glacial Maximum /
• Qinling Mountain range

Abstract: [Objective] The Qinling Mountains serve as a crucial north-south geographical boundary in eastern China, characterized by diverse vegetation types that respond sensitively to climate change. However, systematic analyses of vegetation response mechanisms to natural and anthropogenic factors in this region are still limited, hindering a comprehensive understanding of ecological changes and human-environment interactions in the Qinling area. [Methods] This study is based on the sediment core from Daye Lake, an alpine lake on the Mount Taibai which is the highest mountains in the Qinling Mountain range. Using high-resolution pollen and charcoal records, we quantitatively reconstructed vegetation dynamics since the Last Glacial Maximum (LGM) through Biomisation and diversity indices, and extracted fire frequency and fire intensity sequences using the CharAnalysis software. We combined reliable climate and human activity records with fire activity sequences reconstructed from charcoal, this study systematically examined vegetation response mechanisms to climate change and human activities. Furthermore, statistical methods including redundancy analysis and correlation analysis reveal the contributions of various drivers to vegetation evolution across different time scales. [Results] Findings indicate that vegetation landscape in the Qinling region evolved from a coniferous forest dominated by Picea and Pinus during the LGM to a mixed coniferous-broadleaf forest during the Last Deglaciation, accompanied by pronounced fluctuations in vegetation diversity. During the Holocene, the vegetation transitioned to temperate deciduous broadleaf forests dominated by Corylus/Carpinus and Quercus, accompanied by a marked increase in vegetation diversity. The expansion of herbaceous plants such as Artemisia and Poaceae, along with land openness, occurred in the Late Holocene, while vegetation diversity showed a declining trend. Fire activity exhibited high frequency both in the Last Deglaciation and the Late Holocene, driven respectively by cold-dry climate and human activities. [Conclusion] Since the LGM, vegetation in the Qinling Mountains has shown a significant response to climate change. From the LGM to the Last Deglaciation, both broadleaf and coniferous forests showed significant correlation with temperature. Redundancy analysis confirmed temperature was the dominant factor, while fire activity promoted vegetation diversity by altering interspecific competition patterns and niche availability. However, precipitation strongly correlated with temperate deciduous broadleaf forests during the Holocene, and precipitation became a key controlling factor in vegetation succession with the intensification of the East Asian summer monsoon. Since the Middle Holocene, human activities have emerged as a third significant driving factor, with their influence steadily increasing over time. This study systematically reveals the response patterns of Qinling vegetation to climate change and the process of human intervention, providing a crucial case study for understanding the long-term interaction mechanisms among vegetation, climate, fire, and human activities in alpine regions.