EVERGREEN BROAD-LEAVED FOREST IN TAIWAN AND ITS RELATIONSHIP WITH COUNTERPARTS IN MAINLAND CHINA

There are different understandings of the term evergreen broad_leaved forest (EBLF). In the broad sense it refers to the type of forest vegetation consisting of evergreen broad_leaved trees distributed in areas other than the tropical zone. Taiwan and the eastern part of mainland China are the distributional center of EBLFs. Based on the eco_physiognomy the EBLFs of Taiwan can be classified into three subtypes: subtropical ombrophilous EBLFs, subtropical seasonal EBLFs, and montane EBLFs. According to the floristic characteristics the subtype is further divided into collective_type (or group of alliance) by the dominants and the diagnostic species. Each subtype has one collective_type, that is Ficus_Machilus, Machilus_Castanopsis, and Castanopsis_Cyclobalanopsis respectively. On the basis of dominant species and diagnostic species the collective types are divided into alliance. In this paper 10 communities (similar to alliances) have been described. These are: 1) Dendrocnide meyeniana_Ficus irisana, 2) Adinandra formosana_Machilus japonica var. kusanoi, 3) Neolitsea hiiranensis_Cyclobalanopsis longinux var. koui, 4) Engelhardtia roxburghiana_Castanopsis uraiana, 5) Lasianthus appressihirtus_Castanopsis carlesii var. sessilis, 6) Beilschmiedia erythrophloia_Castanopsis carlesii, 7) Symplocos arisaenensis_Castanopsis carlesii, 8) Fatsia polycarpa_Castanopsis carlesii, 9) Rhododendron ellipticum_Cyclobalanopsis longinux, 10) Acer morrisonense_Cyclobalanopsis longinux. EBLFs of Taiwan are very similar to those of mainland China. Among 388 species occurring at the survey plots (with an area of 7 325 m 2) more than 60% (244 species) are common species with mainland China, and 49% (190 species) with the eastern part of the mainland (Jiangsu, Zhejiang, Anhui, Jiangxi, and Shanghai), some of them are dominant species and diagnostic species. Additionally there are many endemic species in the EBLFs of Taiwan, accounting for 1/5 (84 species) of the 388 total species. Therefore the EBLFs of Taiwan have their own uniqueness. Historically Taiwan was connected with and separated from mainland China several times accompanying fluctuations in sea level, and the last separation occurred 10 000-15 000 years ago. The frequent exchange of species between both sides of the straits brought about resultant similarity not only in the physiognomy but also in the species composition of EBLFs in the both areas. On the other hand the diversifying topography and climate in Taiwan are very favorable for species conservation and differentiation, leading to an abundance of endemic and substituting species in EBLFs of Taiwan.