China’s biodiversity hotspots revisited: A treasure chest for plants

Abstract n/a

mountain ranges along China-Kyrgyzstan and China-Tajikistan borders. The mountains that surround the southern part of the Qinghai-Tibet Plateau, which extend from the western barrens to the humid southeast in Tibet (Xizang), form a significant portion of the "Himalaya" biodiversity hotspot. The "Mountains of Southwest China" biodiversity hotspot is found almost entirely within China, stretching from southeast Tibet, through western Sichuan and extending into northwest Yunnan, with only a narrow range along the western slope of the Gaoligong Mountains, located in northern Myanmar. The northeast part of the "Indo-Burma" biodiversity hotspot begins in the west of Yunnan, crosses over southern Yunnan to central Guangxi and then runs along the coast of southern China from the Guangxi-Vietnam border to eastern Guangdong, including the entire Hainan Island.
Biodiversity hotspots play a substantial role in understanding China's unique flora. Currently, the native vascular flora from China's biodiversity hotspots has yet to be investigated in its entirety and the estimated number of species could be more than 25,000 based on the "Flora of China" and recent surveys (The Biodiversity Committee of Chinese Academy of Sciences 2019). This accounts for approximately three quarters of China's flora. China's biodiversity hotspots are mainly located in remote mountain areas, where access is difficult and there are diverse microclimates. These isolated habitats are often associated with high levels of endemism and there is great potential for the discovery of new plant species in these regions (Joppa et al. 2011). Although rapid economic growth and urbanisation in China is driving landscape modification and environmental deterioration, the flourishing development of infrastructure, such as expansion of road networks, has improved accessibility to remote areas, thereby fostering the discovery of additional undescribed diversity in the country. For example, according to records in the International Plant Names Index (IPNI), 1038 new vascular plant species were described or reported for China from 2013 (the year when the "Flora of China" was completed) to the end of 2018, with some 73% of the species deriving from China's biodiversity hotspots ( Figure 1, Appendix 1). The future discovery of additional new plant species in these regions is likely.
The "Flora of China" represents the most comprehensive catalogue, description and illustration of known vascular plant species of China. However, a few of the early treatments published were essentially updated translations of the "Flora Reipublicae Popularis Sinicae" and for a number of other groups, no specialists were available at the time when the treatments were completed, so that they are in essence preliminary. A great deal of further taxonomic work, often simulated by the "Flora", has improved our understanding of many groups, very often adding to the number of recognised species. For example, recent taxonomic revisions of Chinese Aristolochia, which included only 45 species in the "Flora of China", split the genus into two genera with 78 species in total, of which 19 were newly described (Zhu et al. 2019b, Zhu X.-X. personal communication), two of them in this special issue (Zhu et al. 2019a). It is quite clear than many more species are present in China than are now recognized, and likely that most of these will come from the hotspots.
The application of DNA barcodes and other sequence data in the past decade has helped to improve our understanding of the species and relationships in many groups of plants (Kress et al. 2005, CBOL Plant Working Group 2009, China Plant BOL Group 2011, Hollingsworth et al. 2016. To fully understand the diverse flora of China, these tools must be applied widely (e.g. Liu et al. 2011, Yu et al. 2015.
To better document, understand and conserve China's biological heritage, Chinese scientists have conducted a series of initiatives to facilitate the understanding and conservation of plant diversity, particularly over the past twenty years. These range from baseline, floristic surveys to long-term monitoring studies that document dynamic patterns of biodiversity with a specific focus on Southwest China and the Qinghai-Tibet Plateau, where many ecosystems are being degraded as a result of human activities and global warming . Indeed, much action is urgently needed to mitigate the effect of human disturbance and climate change in these hotspots and elsewhere in China.
With extended collaboration amongst Chinese scientists and coordination of networks on plant conservation and taxonomy across China, we have synthesised a special issue entitled "Revealing the plant diversity in China's biodiversity hotspots", to present the latest findings by Chinese botanists and to update knowledge of the flora for China and adjacent countries. This issue, comprising 18 articles, includes descriptions of 23 species new to science and new insights into the diversity of Scleroglossum (Polypodiaceae) based on DNA barcodes. The new species originate from the following hotspots: Indo-Burma (13), Mountains of Southwest China (2), Himalaya (4), Mountains of Central Asia (1) and 3 from areas with conservation interest outside the hotspots.
The new species published in this special issue reflect ongoing taxonomic and floristic research across China. It is hoped that these new discoveries will contribute to the objectives of the updated Global Strategy for Plant Conservation (GSPC) 2011-2020 and China's Plant Conservation Strategy, in general. In particular, we also strive to facilitate national and local policy-makers to develop more effective conservation guidelines. The naming and describing of new species are fundamental steps for understanding China's natural history and assessing its plant diversity is the first "stepping-stone" to securing the success of our biodiversity initiative. In short, the value of botanical inventories and taxonomic work should be recognised through prioritised funding opportunities, inspired taxonomy training schemes, wider public involvement and an integrated GSPC post-2020 framework.  (1)