Pliocene Wood Flora From Yuanmou Of Yunnan And Taigu Of Shanxi, China

Fossil woods, silicified and charcoal material, are investigated for the first time from the Yuanmou Basin of Yunnan Province and the Taigu Basin of Shanxi Province at the age of Pliocene in present paper. The palaeovegetation, palaeoenvironment and palaeoclimate in these localities are reconstructed based on the biological evidences obtained from the fossil wood flora.1. Yuanmou wood flora in the age of Late Pliocene (Shagou Formation) of the Yuanmou Basin, including Hutiaotan Earth Forest, Wanpu Earth Forest and Xinhua Earth Forest, Yunnan province, China, contains a gymnosperm of Cephalotaxus (Cephalotaxaceae) or Amentotaxus (Taxaceae) and 11 angiosperms of Toona (Meliaceae), Bischofia (Euphorbiaceae), Zelkova (Ulmaceae), Dalbergia (Fabaceae), Castanopsis, Cyclobalanopsis (Fagaceae), Lagerstroemia (Lythraceae), Morus (Moraceae), Juglandaceae, Fabaceae and Fagaceae. The fossil woods of Toona (Meliaceae), Dalbergia (Fabaceae), Castanopsis, Cyclobalanopsis (Fagaceae), Lagerstroemia (Lythraceae), Morns (Moraceae), Juglandaceae and Fabaceae are reported in China for the first time.Evergreen broad-leaved plants like Castanopsis and Cyclobalanopsis (Fagaceae)mixed with needle leaf plants such as Cephalotaxus (Cephalotaxaceae) or Amentotaxus (Taxaceae) grow on the high lands around the basin, while plants of Toona (Meliaceae), Bischofia (Euphorbiaceae), Lagerstroemia (Lythraceae) and Fabaceae etc. are accustomed to grow inside the basin under warm and humid subtropical climate.Compared with contemporaneous flora of India, the Yuanmou flora does not have the typical tropical rain forest elements like Dipterocarpaceae, which is very common in the Tertiary floras in India. The difference between the floras of two countries was resulted from Pliocene climate, that was formed as a result of Himalaya uplifting and flora origin.2. Taigu wood flora in the age of Late Pliocene (Xiaobai Formation) of the Taigu Basin, Shanxi Province, China, contains Ulmus (Ulmaceae), Prunus (Rosaceae) and Cudrania (Moraceae). Dicotyledonous charcoal woods of Tertiary are discovered for the first time in China. The elements of this flora demonstrate that typical temperate climate in the basin during Pliocene. Fossil woods with distinct growth ring show that the climate has seasonal change obviously during that time. The modern temperate plants possess high incidence of distinct helical thickenings on vessels. The fossil wood vessels from Taigu showed the distinct helical thickenings. It is an additional evidence for comparing the modern temperate climate with the Pliocene one in the Taigu basin. The abundant layers of charcoal and gypsum indicate that wild fire occurs under the dry climate frequently. The Taigu wood flora enriched the Pliocene flora of the Taigu Basin and provide new evidences for the reconstruction of palaeovegetation, palaeoenvironment and palaeoclimate there.