A Preliminarily Study On Karst Cave Plants In Guangxi, China

Based on references, field investigations, and on identification of specimens, we study the floristic composition characters, endemism, rare endangered plants in karst caves in Guangxi, and inspect the characteristics of these specific populations. The main results are as follows,1. There are 489 species (including subspecies and varies), belonging to 268 genera and 101 families of vascular plants in karst caves in Guangxi, most of which are Angiosperms. There are only 67 species, belonging to 27 genera and 13 families, are Pteridophytes. No Gymnosperms was recorded.2. Five new taxa were found in the study on karst cave flora in Guangxi. They are Chiritopsis jingxiensis, Lagarosolen jingxiensis, Wentsaiboea luochengensis, Primulina guangxiensis, Paraboea trisepala.3. As for Pteridophytes, dominant families include Dryopteridaceae, Pteridaceae, Selaginellaceae and Adiantaceae, which covers 55.1% of all the Pteridophytes species. The distributional types of families are mainly tropical, which are composed of 46.2% of all the types. On comparing, the temperate types are only 7.1% of all. The most important genera are Pteris, Selaginella, Adiantum, Dryopteris, Asplenium, and Tectaria, and species of them contribute to 58.2% of the total Pteridophytes species. There are 13 genera are tropical distribution type, which covers 72.2% of all the types. Thus, we propose that the property of Pteridophytes flora in karst caves in Guangxi is tropical rather than temperate on both families and genera rank.4. The dominant families of Angiosperms are Gesneriaceae, Urticaceae, Begoniaceae, Rubiaceae, Compositae, Euphobiaceae, Moraceae, Araceae. The tropical type is dominant in the distribution type of Angiosperms families, which includes 57 families, and covers 80.3% of the total types. Among the tropical distribution families, 47 of them, which covers about 66.2% of the total familis, belong to pantropic type. The dominant genera of Angiosperms are Begonia, Chirita, Chiritopsis, Elatostema, Ficus, Pilea, Tetrastigma, Impatiens, Paraboea, Lysionotus, Carex, and Lysimachia. 160 among 241 genera are tropical distribution, which covers 72.3% of the total genera, and is the most prominent distribution type in all. Pantropic type and tropical Asia type are very evident. It includes 55 genera and 52 genera, covers 24.8% and 23.5% of the total genera, in respectively. We conclude that the flora of Angiosperms is tropical.5. The endemic vascular plants in karst caves in Guangxi are abundant. There are 12 genera endemic to China, namely Chiritopsis, Calcareoboea, Lagarosolen, Metabriggsia, Petrocodon, Primulina, Wentsaiboea, Bolbostemma, Gymnotheca, Heteroplexis, Tetrapanax, and Thyrocarpus, in which three of them, Metabriggsia, Wentsaiboea, Heteroplexis are endemic to Guangxi. There are 182 species, 37.2% of all species we record in karst caves in Guangxi endemic to China, and 67 species among them, namely 13.7%, are endemic to Guangxi. The most prominent endemism are in families as Gesneriaceae, Urticaceae, Begoniaceae, Rubiaceae and Primulaceae.6. We investigated plant communities in 10 typical karst caves using typical quadrat method. The basic characteristics of karst cave plants community are respected by poor richness and evident dominant. The species diversity index of Simpson is 0.352-0.805. Chamaephytes are dominant in life form spectra of these kinds of community.7. There are 25 rare and endangered species in karst caves in Guangxi, belonging to 13 families and 20 genera. Among them, 3 species are on the List of Rare and Endangered Plants Under State Protection (Vol. 1, 1978), 2 species are on the List of Wild Plants Under State Key Protection (1999), and the rest are on the List of Threatened Plants Growing on Limestone in South and Southwest China. According to the IUCN,s Evaluation Standards of Endangered Species and the reality conditions we observed, we strongly suggested that some rare and important value species need to be added into the list of wild plants under state. Finally, we also analyses the endangered causes of rare and endangered plants, and give some suggestions for protection and conservation them.