Indeed, describing his own encounter with a tiankeng back in 2016, researcher Tang Jianmin wrote: “The scene down there was stunning: an underground pristine forest with no trace of human ...

Tiankeng are refuges for modern karst forest plants, including the Nepali hog plum (Choerospondias axillaris) and the Chinese rain bell (Strobilanthes cusia), they wrote. For the study ...