Produced by: Mohsin Shaikh
China’s tiankeng, or “heavenly pits,” defy the sinkhole stereotype. These massive chasms harbor pristine ancient forests and species unknown to science, offering an otherworldly glimpse of untouched ecosystems.
A tiankeng discovered in 2022 measures 300 meters long, 150 meters wide, and 190 meters deep. Located in southwestern China, it’s one of 30 in the region protecting rare plants and animals from human interference.
Tiankeng bottoms host ancient trees up to 40 meters tall. Tang Jianmin described them as lush, untouched ecosystems with no trace of human activity—a scene he likened to stepping back in time.
Representative pic
Plants in tiankeng thrive on abundant nitrogen, phosphorus, and other nutrients. A July 2023 study revealed how these elements, scarce elsewhere, fuel the growth of towering vegetation despite limited sunlight.
These sinkholes are home to unique species like the Nepali hog plum and Chinese rain bell. Modern karst forest plants thrive in moisture-rich, shaded environments far removed from human disruption.
Credit: China's Ministry of Natural Resources via Xinhua
Tiankengs form when underground chambers collapse, creating enclosed, humid environments. Connected to subterranean rivers, their lush ecosystems flourish in high humidity and low temperatures, explains Tang Jianmin.
China is home to two-thirds of the world’s 300 tiankeng, found in its UNESCO-listed South China Karst. Similar sinkholes exist in Papua New Guinea, Croatia, Italy, and Madagascar, among other countries.
Credit: China's Ministry of Natural Resources via Xinhua
Tiankengs serve as ecological sanctuaries for rare and endangered species. Researchers have discovered endemic plants and animals, reinforcing their importance as “primitive forest ecosystems,” says Jianmin.
Credit: China's Ministry of Natural Resources via Xinhua
With their isolation and unique conditions, tiankengs remain largely unexplored. Experts believe these sinkholes may hold unknown species, preserving secrets from a world untouched by human hands.