The endangered tree Michelia coriacea Chang et B. L. Chen (Magnoliaceae) is endemic to southeastern Yunnan, China. It is found in limestone outcrop habitats in a few localities at 1300–1700 m. Its habitat has been severely fragmented and degraded by overexploitation, including logging, road construction, and agricultural development in recent decades, with only 4 populations remaining at present. The population dynamics of M. coriacea are practically unknown. We investigated all 4 populations and studied the demography and ecology to create a scientific base for recommendations on conservation and restoration of the species. The census was repeated in 5 consecutive years from 2006 to 2010. Over that period, the annual mortality rate was 68.9% during early recruitment (individuals under 70 cm high), but mortality decreased to 23.3% after seedling/sapling establishment. The population of M. coriacea is clearly declining. The major factor threatening its continued existence is poor regeneration caused by ecological conditions, including habitat destruction, invasive plants, and low recruitment. Unless conservation measures are undertaken, the species will not maintain its natural population. The information provided here will apply to conservation of not only M. coriacea but also other plants having similar population dynamics and growing in unprotected areas in fragile mountain ecosystems.