Microcharacters Of Four Fossil Plants From Pliocene In Tengchong Of Yunnan Province

Global temperature has clearly increased since the Industrial Revolution. The phenomenon of global warming is more obvious in the 21st Century than in the 20th Century. Greenhouse effect owing to atmospheric CO₂ enrichment is a great cause of global warming. Accordingly, understanding the relation between stomatal parameter and atmospheric CO₂ concentration is advantageous to predicting global climate trend.Four angiosperm fossil leaves having resemblance in appearance were studied in this work. They are Alseodaphne hainanensis Men., Litsea grabaui Hu et Chaney, Machilus cf. leptophylla Hand.-Mazz. and Magnolia paenetalauma Dandy, which were collected from the Pliocene Mangbang Formation in Tengchong, Yunnan Province, where the four fossil leaves were found for the first time. The epidermal microstructures of these species were investigated based upon extensive experiments in laboratory. The epidermal characteristics of the four plant fossils are different obviously, which shows the significances of epidermal characteristics in taxa to a great extent. The application of a scanning electronic microscopy provides exact and fine diagnosis for the classification of angiosperm.The enlargement of geographical distribution and the extension of geological age of fossil Alseodaphne hainanensis indicate that Pliocene climate was warmer than present-day in the area of Western Yunnan. Altitudinal increase and the decrease of temperature in the area of Western Yunnan have make modern Magnolia paenetalauma retreat from Yunnan, which further demonstrates that the temperature gradually decreased from Pliocene to present in the area of Western Yunnan Province. A detailed comparison of the cuticle and the leaf architecture between fossil Machilus cf. leptophylla and modern Machilus leptophylla reveals that fossil Machilus cf. leptophylla grew in humid climate. The result shows that Pliocene climate is warm and humid in Tengchong, Yunnan Province.Selecting modern Alseodaphne hainanensis and Machilus leptophylla as Nearest Living Relative species respectively and counting their stomatal parameter, we try to reconstruct Pliocene CO₂ concentration of Tengchong in Yunnan Province with Stomatal Ratio. The two data (Alseodaphne hainanensis 417.6ppmv and Machilus leptophylla 438ppmv) all fall into the error scope of revised GEOCARB III. Palaeoenvironmental reconstruction in the time has a profound significance for understanding global environmental change.