Research On Cuticles Of Five Fossil Plants From Pliocene In Tengchong Of Yunnan

The microstructures of five fossil angiosperm leaves from the Pliocene Mangbang formation of Tengchong in Yunnan Province were studied in the present paper. The five fossil leaves are Excentrodendron hsienmu (Chun et How) H. T. Chang et R. H. Miau, Machilus thunbergii Sieb.et Zucc, Cyclobalanopsis chevalieri (Hick et A.Camus), Mangifera indica L and Aquilaria agallocha Roxb. Much work had been done about the epidermal characters of these fossil leaves and their microstructures greatly increase the correct defining of fossil angiosperms, and provide strong evidence to classification of fossil angiosperms.As tree leaves act as important interfaces of interaction of plants and their outer environment, fossil plant leaves have an important rule in reconstructing palaeoatmosphenc CO₂ concentration and in understanding the interrelation of the atmosphere and the biosphere. A comparison between stomatal parameter of the fossil Excentrodendron hsienmu and that of its nearest relative species Excentrodendron tonkinese was made and the Stomatal Ratio Method was applied in reconstructing the palaeoatmosphenc CO₂ concentration at the time of the Pliocene in Tengchong, Yunnan (422.4ppmv), which shows that the fossil species Excentrodendron hsienmu can be used as a bioindicator of the palaeoatmosphenc CO₂. The present work is of great importance for us to recognize the influence of the global atmospheric CO₂ concentration on stomatal frequency, for reconstructing ancient. atmospheric CO₂ concentration by using fossil leaves and for understanding interrelationship between climate and biosphere.