台灣殼斗科植物多樣性與鄰近地區的關係及其在東亞地區的地理分布

Fagaceae Species of Taiwan Relates to That of Neighboring Regions and Their Distributions in East Asia

本研究分析東亞地區殼斗科植物多樣性及台灣殼斗科植物在東亞地區的地理分布趨勢，探討中國西南地區作為植物在第四紀冰河時期的“避難所”，是否對於台灣植物多樣性的貢獻比東亞熱帶地區重要。本研究主要由Global Biodiversity Information Facility（GBIF）、台灣植物誌及中國植物誌等收集資料，比對之後得到東亞地區殼斗科植物8屬465種。將東亞地區除了台灣以外分為7個地理區，結果發現，東亞地區以北緯20～30度之間的中國華南地區殼斗科物種多樣性最高，有7屬285種。值得注意的是，物種多樣性由亞熱帶地區往熱帶及溫帶地區下降。其它5個地理區，包括熱帶地區的中南半島、馬來群島、華中地區、東北亞及華北地區的物種多樣性皆較華南地區低，且華北及熱帶的新幾內亞分別只有7種及12種。台灣的殼斗科植物有4屬46種，除特有種11種外，與華南的共有種33種最多。且與熱帶的馬來群島及新幾內亞的共有種數相當低，分別只有1及0種。此外，台灣殼斗科物種的分布範圍，以涵蓋台灣到中國西南地區的物種最多。台灣殼斗科植物與中國西南方的相關性最高，可能是氣候及生態條件類似及陸橋連接所致；與熱帶地區的相關性低，則可能是殼斗科植物短距離傳播的特性及台灣與熱帶島嶼之間的海洋隔離所造成。

The present study is a biogeographical distribution analysis of plant species in Taiwan and floristic relationships between Taiwan and neighboring areas in East Asia. Using Fagaceae species, we attempted to find out which area, tropical area or refuge in southwest China, is more important to the species richness of Taiwan. Floristic data were mainly downloaded from Global Biodiversity Information Facility (GBIF), and comparisons were made based on floristic checklists of GBIF and data from Flora of China and Flora of Taiwan. Consequently, eight genus and 465 species of Fagaceae were observed in East Asia. East Asia excluding Taiwan was divided into seven biogeographical areas to compare the differences of floristic compositions. Among the seven biogeographical areas, southern China between 20 and 30 °N latitude possessed the highest species richness of Fagaceae, with seven genus and 285 species observed. Surprisingly, species richness was not highest in tropical Asia but decreased from subtropical toward tropical and temperate areas. Species richness of the other five biogeographical areas, including Indochina (4 genus, 127 species), Malay Archipelago (3 genus, 53 species), central China (6 genus, 99 species), Northeast Asia (6 genus, 43 species) and northern China (2 genus, 7 species), was lower than that of southern China. New Guinea possessed the lowest species richness of Fagaceae in Southeast Asia with only three genus and 12 species observed. There are four genus and 46 species in Taiwan. Among them, 11 are endemic species. Similarity index was highest between Taiwan and southern China, and was lowest between Taiwan and tropical areas. In conclusion, Taiwan and southern China have the highest floristic relationships, and most of the Fagaceae species in Taiwan are distributed from Taiwan to southern China. Ecological similarity and land bridge between Taiwan and China were probably responsible for the close floristic relationship between these two areas, whereas dispersal characteristics of Fagaceae species were probably related to the low relationship between Taiwan and tropical areas.