关键词: 洞穴植物, 弱光带, 穴居, 物种发现, 极端环境

Abstract

Aim: Caves are widespread geological structures within karst landscapes which is associated with diverse flora. In the last 20 years, dozens of new species from Chinese caves have been described, many of which are not in the current list of the Chinese cave flora. In this study, we aimed to generate an updated list of China’s cave flora to better reflect the species diversity and endemism of the ecosystem and raise attention to its importance for the conservation and sustainable use of biological diversity.
Methods: We created a catalogue of all the Chinese cave plants by integrating the published regional lists of cave plants and reviewing the publications describing newly discovered species from Chinese caves. We utilized this information to generate an updated list of China’s cave flora of vascular plants. All accepted names were retained while the repetitive and unidentified names were eliminated based on the database of Plants of the World Online (POWO). The characteristics of the cave flora, the species distribution within caves, and the IUCN status of each species’ were analyzed.
Results: From 2001 to 2020, one new genus and 170 new species (including infraspecific taxa) belonging to 31 genera and 16 families (APG IV and PPG I classifications) of vascular plants were described from karst caves in China. We documented 871 species belonging to 339 genera and 110 families of vascular plants from the karst caves mainly in the provinces of Chongqing, Guangdong, Guangxi, Guizhou, and Yunnan. The five most common families identified in caves were Gesneriaceae, Urticaceae, Dryopteridaceae, Begoniaceae, and Rubiaceae, accounting for 39.4% of the total cave plant species. The five most commonly identified genera were Primulina, Elatostema, Polystichum, Begonia, and Pteris, accounting for 25.1% of species diversity. Herbaceous species constitute over half of the cave flora, and 10.7% of species occupy the twilight zone. In comparison with angiosperms, the proportion of lycophytes and ferns in the twilight zone was higher, suggesting that they adapt easier to the extreme habitats of twilight zones. Furthermore, there were high levels of endemism of vascular plants in caves. There were 225 provincial endemic species, accounting for 25.8% of the total cave plant species. Among these, the proportions of non-cave endemism, multiple cave endemism, and single cave endemism were 11.0%, 3.3% and 11.5%, respectively. A total of 115 species (13.0%) were under threat of extinction according to the literature review. The most threatened families were those with newer species published in recent years, including Dryopteridaceae, Gesneriaceae, Urticaceae, Begoniaceae, and Rubiaceae. More detailed investigations should be conducted to refine the IUCN assessments of these taxa. In addition, molecular data are lacking for at least 36% of the species in our list.
Conclusions: Our updated list suggests that caves are important for species discovery in China. Further investigations in caves are needed, particularly in Yunnan, Chongqing, and Hunan. We propose that most cave plant species probably originated from the karst forest understory and are therefore of great significance for the restoration of native karst vegetation and the combatting of desertification. For this reason, China’s cave flora should be further documented and protected.

Key words: cave plant, twilight zone, cavernicolous habitat, species discovery, extreme environment