Trillium tschonoskii

Information on the total population of the species is sparse. Reports from China confirm unsustainable harvest of the species leading to a decrease in population size (Li et al. 2005, Hu and Qian 2009). A survey of seven natural subpopulations of T. tschonoskii from Sichuan Province, China revealed extensive habitat loss due to heavy deforestation (Li et al. 2005). The species has rare occurrences in Korea (Ahn et al. 2007), Tibet (Xizang) (Wan-ze 2005), and India. Likewise, in Japan, its subpopulations once abundant have become extinct or highly fragmented due to extensive timber harvest (Ohara and Kawano 2006). 

In some areas of its distribution in China, such as northwestern Yunnan, northwestern Zhejiang, northern Fujian, and southeastern Gansu provinces, human disturbance has led to the scarcity or even disappearance of several subpopulations (Li et al. 2005). Given its rare occurrence along with steady depletion, and a generation length of 25 to 33 years for T. tschonoskii, the population declines between 2000 and 2090 (the shortest estimated three-generation window for which population data are available) are very likely to be greater than 50% and could exceed 80% triggering Critically Endangered status for the species. Undocumented population declines of the species are probably occurring within its distribution range. Due to high demand for ethnobotanical and pharmaceutical uses and human disturbances threat to the remaining subpopulations of the species are unlikely to be mitigated in the foreseeable future.