Bot. Rev. (2010) 76:346–376 DOI 10.1007/s12229-010-9055-7 Seed Plant Endemism on Hainan Island: A Framework for Conservation Actions Javier Francisco-Ortega1,2 & Zhong-Sheng Wang3,12 & Fa-Guo Wang4 & Fu-Wu Xing4 & Hong Liu2,5 & Han Xu6 & Wei-Xiang Xu3 & Yi-Bo Luo7 & Xi-Qiang Song8 & Stephan Gale9 & David E. Boufford10 & Mike Maunder1,2,11 & Shu-Qing An3,12 1 Department of Biological Sciences, Florida International University, Miami FL33199, USA 2 Center for Tropical Plant Conservation, Fairchild Tropical Botanic Garden, Coral Gables, Miami, FL 33156, USA 3 Laboratory of Forest Ecology and Global Change, School of Life Science, Nanjing University, Nanjing 210093, People’s Republic of China 4 South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, People’s Republic of China 5 Department of Earth and Environment, Florida International University, Miami FL33199, USA 6 Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, People’s Republic of China 7 Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing 100093, People’s Republic of China 8 Key Laboratory of Tropical Horticultural Plant Resources and Genetic Improvement, Hainan University, Haikou 570228, People’s Republic of China 9 Kadoorie Farm and Botanic Garden, Lam Kam Road, Tai Po, New Territories, Hong Kong SAR, People’s Republic of China 10 Harvard University Herbaria, 22 Divinity Avenue, Cambridge, MA 02138, USA 11 Al Ain Wildlife Park and Resort, PO Box 1204, Al Ain, Abu Dhabi, United Arab Emirates 12 Authors for Correspondence; e-mail: [email protected]; [email protected] Published online: 20 May 2010 # The New York Botanical Garden 2010 Abstract Hainan, the second largest island of China, has the most extensive and best preserved tropical forests of this country. A network of 68 protected areas (54 of them are terrestrial) provides in situ conservation for the unique ecosystems of the island. We: (1) discuss an updated check-list of seed-plant species that are endemic to Hainan, (2) evaluate the extent to which the endemic flora has been the subject of molecular studies, and (3) investigate the conservation status of these species. We recognize 397 endemic species on the island, 271 of which are reported in the protected areas, and 144 of which have been Red-Listed (85 assigned to the Critically Endangered (40) or Endangered (45) IUCN categories). The families with the highest number of endemics are Rubiaceae (33 species), Lauraceae (27 species), and Poaceae (26 species). The island has only seven endemic genera, all of which are unispecific. Compared with other tropical islands, Hainan has a low number of endemics but our preliminary observations suggest that the island has a highly disharmonic flora when compared with that from the mainland. Nevertheless, most of the major clades of the seed-plant tree of life with representatives in China also have endemic species on the island. We argue that the low levels of endemism reflect Seed plant endemism on Hainan Island 347 the continental nature of Hainan and the fact that several areas of the island have not been fully inventoried. We were unable to find a single molecular systematic study focusing exclusively on the Hainan endemics; however, 24 of the endemic species have been included in phylogenetic studies targeting particular genera or families. Future research/conservation actions for the endemic flora of Hainan should focus in developing: (1) a red-list that assesses all 397 endemic species, (2) comprehensive floristic studies for the protected areas, (3) molecular phylogenetic and conservation genetic studies with a primary focus on the endemics, (4) studies to understand what ecological interactions are important in the biology of the endemic species, and (5) eco-geographical studies to identify Important Biodiversity Zones of endemism within Hainan and therefore potential new protected areas. Keywords Asia . DNA Systematics . Angiosperms . Gymnosperms . Indo Burma Biodiversity Hotspot . Tropical botany Introduction Hainan: Physical and Ecological Features Hainan, with an area of approximately 33,900 km2, is the second largest island of China (Fig. 1). It is located at the same latitude as northern Vietnam, and is only 24 km from the Leizhou Peninsula, Guangdong Province. Because of the relatively shallow waters of the Qiongzhou Strait (maximum depth of 120 m) (Cheng et al., 2008), it is likely that the island has been successively connected with and separated from the mainland during the recent Quaternary glacial and inter-glacial periods (Long et al., 2006). Hainan and its surrounding islands are the southernmost territory of the People’s Republic of China; therefore, it is the region of this country with the strongest tropical influence. Accordingly, some authors have argued that the flora of Hainan and other areas of southern China should be placed within the Indo-Malesian floristic subkingdom (Zhu & Roos, 2004). Hainan has a complex geological origin, greatly determined by the expansion of the South China Sea Basin and by tectonic interactions between the Eurasian, Philippine and Indian plates (Liu et al., 2008). The island is volcanically active and sits on a geological hotspot or mantle plume (Zhao, 2007); the latest volcano eruptions took place in 1883 and 1933 at Lingao and Chengmai counties, respectively (Liu, 1999). Geologically, Hainan was originally part of two different blocks of Gondwana that merged with Eurasia during the Late Permian to Middle Triassic (Cai & Zhang, 2009). Previous studies claim that the island began to separate from the mainland along a fault-line that developed in the Qiongzhou Strait during the Quaternary (Wang et al., 1995a; Xing et al., 1995; Zhao et al., 2007; Yao et al., 2009). However, results of tectonophysical and marine sediment studies suggest that Hainan began to split from the mainland much earlier, during the Tertiary. The Qiongzhou Strait is located on the eastern margin of the Beibuwan Basin (Fig. 1), and it is believed that this submerged geological depression developed in the late Cretaceous or Tertiary (Ren et al., 2002). Additional support for a pre-Quaternary origin comes from the 348 J. Francisco-Ortega et al. Fig. 1 Map of Hainan Island and southern portion of Leizhou Peninsula showing location of four protected areas (coded 1 = Bawangling; 2 = Diaoluoshan; 3 = Jianfengling; 4 = Yinggeling) discussed in our review presence of massive Tertiary marine sediments in the Qiongzhou Strait (Li et al., 2008; K.-J. Zhang, pers. comm.). Seismic studies undertaken by Peng (2000) support an Oligocene origin for Hainan, suggesting that marine erosion played a major role in its insular origin. In addition, these seismic data do not support the existence of any major geological fault along the strait (Peng, 2000). Seed plant endemism on Hainan Island 349 The complex geology of Hainan has resulted in an environment that includes volcanic rocks in the northern region, granitic and metamorphic rocks mostly in the center, south and southeastern sectors, and limestone deposits primarily confined to the southwestern corner of the island (Zhou et al., 1999; Li et al., 2000; Xing et al., 2004; Ding et al., 2005; Qin et al., 2005; Lei et al., 2009). The northern portion of Hainan has an overall elevation of 300 m and is relatively flat. In contrast, the southern and central regions have a highly dissected topography. Wuzhi Shan (1,876 m), the highest mountain, is located in the center of the island. Approximately 39% of Hainan is covered by mountains and hills, including at least 87 peaks with an altitude of more than 900 m (Hsieh & Zhong, 1990). Hainan has a tropical climate dominated by the summer monsoon with a dry season extending between November and April and a rainy season between May and October. The average annual rainfall is over 1,600 mm, but this is not evenly distributed because of the orography of the island. The eastern section of the island receives an annual average precipitation of 2,000–2,400 mm whilst in the western sector this value is reduced to 1,000–2,000 mm (Hsieh & Zhong, 1990). During the rainy season, the island is in the path of typhoons (Wu et al., 2007; Wang et al., 2008). Because of its varied topography and uneven distribution of rainfall, the vegetation of Hainan, which has been severely influenced by human activities (see below), is rich and varied. Currently, the plant communities of Hainan survive in a highly fragmented landscape that includes natural areas, human settlements, and farmland (Wang et al., 2007a). The western semi-arid region has the only tropical savannas in China (Li et al., 2007). Tropical monsoon forests with evergreen and deciduous elements also exist in this region and in the lowlands of southern Hainan (Wang et al., 2007a). Most of the remaining natural vegetation is primarily composed of lowland or montane seasonal evergreen rainforests (Wang et al., 1995a, 2007a). At higher elevations (above 1,300 m) are elfin and tropical evergreen forests where lichens, mosses, small trees/shrubs, and conifers dominate (Wang et al., 1995a, 2007a; Ouyang et al., 2001). The coastal areas include mangroves, xerophytic thorn scrub, forests over sand, and seasonal evergreen forests (Huang et al., 1995; Wang et al., 2007a). In addition, Hainan has some small patches of tropical bamboo forests, mostly located in the central and southern parts of the island (Wang et al., 2007a). Hainan Biota: A Major Conservation Priority in Asia Hainan is the largest island of the Indo Burma Biodiversity Hotspot and has the best preserved and most extensive tropical forests in China (Deng et al., 2008; Zang & Ding, 2009). The island is the site of the Hainan Island Monsoon Rain Forest Ecoregion, one of the 26 terrestrial habitats of China internationally recognized by the World Wildlife Fund for its global ecological importance. In addition, its coastal plains are part of the South China–Vietnam Subtropical Evergreen Forests Ecoregion.