Palaeovegetation evolution and its response to the climate change since Middle Pleistocene in the North China Plain

The climate transition and the terrestrial vegetation ecosystem evolution since Middle Pleistocene are outstanding hotspot in recent global change studies. Based on pollen analysis and the magnetostratigraphy in G3 core in the eastern part of the North China Plain (NCP), the palaeovegetation since Mid Pleistocene was reconstructed. It reveals the vegetation evolution process and climatic response of NCP during the same time. The results show that the process of regional vegetation evolution can be divided into four stages: 1.6~1.2Ma, warm temperate coniferous and broad-leaved mixed forest with relative high density; 1.2~0.7Ma, mainly open warm temperate deciduous broad-leaved forest; 0.7~0.3Ma, broadleaf woody grassland; 0.3~0Ma, alternate appearance of mainly deciduous broad-leaved forest and woody grassland. The most significant vegetation change in NCP occurred at the time point 1.2Ma, which was around oxygen isotope stage 36 corresponding with the so-called Mid Pleistocene climate transition. At the time point, both broadleaf and coniferous forest proportions declined, while grassland dominated by Chenopodiaceae, Artemisia and Gramineae increased significantly. At about 0.7 Ma, the forest in NCP deteriorated further and regional vegetation transformed from deciduous broad-leaved forest to woody grassland. Since 0.3 Ma, the proportion of arbores has risen again. The impact of climate cycles on vegetation is also shown in the pollen spectrum. Before 1.2Ma, the vegetation represented mainly the alternate development of warm temperate and temperate forest types, and after 1.2Ma, the vegetation mainly represented the alternate development of forest and grassland.