Phytosociological Study of Quercus variabilis Forest in Warm-Temperate China

Deciduous Quercus forest is a typical forest type in the warm-temperate zone of China (sensu sinico). Among different kinds of deciduous Quercus forest, Quercus variabilis forest is the important, major forest type in the southern part of this area. In order to clarify the phytosociological characteristics of Q. variabilis forest in warm-temperate China, this study surveyed 12 sites and recorded 54 relevés, using the Braun-Blanquet (1964) methodology (Fujiwara 1987, 1997); a syntaxonomical scheme for Q. variabilis forest was also made. The classification result showed that there were five communities, five associations grouped into three alliances, an order Quercetalia variabilis ord. nov. and the class Quercetea variabilis class. nov. This can be subdivided into: (1) a Lonicero standishii-Quercion variabilis all. nov., consisting of an Acer grosseri-Quercus variabilis comm. nov., a Junipero formosanae-Quercetum variabilis ass. nov., and a Vitici negundo heterophyllae-Quercetum variabilis ass. nov., on very poor soil over granite; (2) a Carpino turczaninowii-Quercion variabilis all. nov., composed of Rhododendron mariesii and Melica radula communities, and a Viburno mongolicae-Quercetum variabilis ass. nov., which can always be found at higher elevation on south-facing aspects; and (3) a Pistacio chinensis-Quercion variabilis all. nov., which includes a Pteroceltio tatarinowii-Quercetum variabilis ass. nov., an Alangio chinensis-Quercetum variabilis ass. nov., and Vitex negundo and Zelkova schneideriana communities, usually occurring on limestone at relatively low elevation. De-trended correspondence analysis (DCA) was performed to distinguish the spatial distribution characteristics of the different communities. The result showed that the communities classified are mostly related to elevation and climatic variables such as mean annual temperature, mean annual precipitation, and mean temperature of the warmest and coldest months. This indicates that, even within the same forest type, Quercus variabilis forest shows very different floristic composition and environmental characteristics across the warm-temperate zone of China.