Tertiary relict plant Liquidambar acalycina Chang on Mt.Tianmu in Eastern China:Characteristics of the community and the ecological significance

The floristic composition,physiognomy and community structure of Liquidambar acalycina forests at the typical sites have been studied in this paper.The results showed that a total of 177 species of vascular plants were recorded,belonging to 128 genera and 65 families. The analysis of floristic geographical elements indicated that the areal-types are complicated and the dominant elements are of the temperate type.An analysis of life form spectrum and leaf characters showed that the physiognomy of these communities was characterized by phanerophytes with meso-and microphyllic-herbaceous simple leaves.In these forests,four distinct layers were distinguished from the forest floor to the canopy,namely the herb layer,the shrub layer,the subtree layer and the tree layer,respectively.In conclusion,the L.acalycina communities were remnant forests that characterized by deciduous phanerophytes with meso-and microphyllic-herbaceous simple leaves.The biogeography of L.acalycina forests were divided into the southern and northern part of mid-subtropical zone.The ratio of deciduous elements and cool-tolerated evergreen elements were increased while the latitude was raised.There were more Tertiary relict tree coexisted in the L.acalycina forests at higher latitude.Hence,more studies on evolution history and community dynamics of L.acalycina forests should been developed for explaining the origin and evolution of Liquidambar genus and the effects of ice age on Tertiary forests.