Long-term dynamics and driving mechanisms of plant communities in a temperate estuary in eastern China based on pollen analysis: A case study of the Liaohe Estuary

Haoran Liu ^1,2 Weiwei Liu ^1,2 Jinzhi Wang ^1,2 Wei Li ^1,2 Jingwen Zhang ^1,2 Jian Gong ^1,2 Lijuan Cui ^1,2*

• ¹ Chinese Academy of Forestry, Beijing, China
• ² Key Laboratory of Wetland Conservation and Restoration, Beijing, China

The Liaohe Estuary, a representative estuary in eastern China, has undergone significant changes in plant community characteristics due to climate change and human activities in recent years. This study conducted a comprehensive analysis of the composition, trends, and environmental drives of plant communities in the Liaohe Estuary from 1944 to 2022 using sediment 210 Pb dating, pollen analysis, and environmental factor indicators. The findings revealed that the plant community in the Liaohe Estuary was predominantly composed of herbaceous plants, thriving under a cool and humid climate. However, humidity showed a decreasing trend over time. Between 2001 and 2022, pollen concentration and the prevalence of herbaceous plants increased clearly. Key environmental factors, including mean annual temperature (MAT), salinity, grain size, pH, and agricultural production, were strongly correlated with the plant communities in the Liaohe Estuary (p < 0.001). Natural factors, such as grain size and salinity, enhanced the dominance of key species within the community, but reduced the overall pollen concentration. In contrast, agricultural production, dominated by human activities, reduced the proportion of these dominant species to some extent while enhancing overall pollen concentration. It provides a theoretical foundation for the restoration and reconstruction of vegetation in degraded estuarine ecosystems.