Trillium camschatcense

Trillium camschatcense is primarily threatened by excessive harvesting of its rhizomes/roots for ethnobotanical uses in China (Shao et al. 2016). The species has also experienced extensive habitat loss due to deforestation and agriculture development (Shao et al. 2016, Tomimatsu and Ohara 2004). Adverse effects of habitat fragmentation have been well documented; smaller subpopulations of T. camschatcense exhibit reduced recruitment (Ohara et al. 2006, Tomimatsu and Ohara 2002, 2004). Habitat fragmentation in Trillium spp. is known to isolate subpopulations and increases proximity to relatively unfavourable habitat edge (Chauhan et al. 2019, Kahmen and Jules 2005, Tallmon et al. 2003). The species is long-lived and very slow to reach flowering/reproductive maturity (about 10 years) (Ohara and Kawano 2005); recovery from disturbance may take several years.

Seeds of T. camschatcense exhibit strong double morphophysiological dormancy (Kondo et al. 2011). Seeds need cold stratification during the first winter after dispersal for radicle emergence, followed by the summer for root and bud development and finally a second winter for shoot emergence (Kondo et al. 2019). This becomes a limiting factor for the artificial cultivation of the species (Shao et al. 2016). Seeds of the species can also be eaten by animals (Tomimatsu and Ohara 2003). Beetles interfere with the dispersal of seeds by eating the elaiosomes of the seeds and making them less attractive to ants (Ohara and Kawano 2005). Grazing by Sika Deer (Cervus nippon) is known to have a negative impact on the long term survival of the species (Inatomi et al. 2017), and similar impacts have been noted for cervid predation in other Trillium species (Dávalos et al. 2014, Knight 2007). Despite recent efforts to reduce Sika Deer population on Hokkaido Island, the species’ population remains historically very high (Uno et al. 2009). The germination phenology of the species may shift with global warming and the growth and establishment of seedlings may be affected with a rise in temperature (Kondo et al. 2019)

Wild collection of species for ethnobotanical uses in China could be offset by the cultivation of the species in natural as well as other suitable habitats. Soaking seeds in warm water prior to stratification significantly accelerates the germination of its seed (Shao et al. 2016). Development of propagation protocols and in vitro production of secondary metabolites would be critical for meeting its ethnobotanical/pharmaceutical demand. Legal protections in the areas of over-harvest (such as China) may help in the protection of some of its subpopulations.

Tomimatsu and Ohara (2003) confirmed that large subpopulations of T. camschatcense are needed to avoid allelic losses and to retain high allelic diversity. At least 550 flowering plants are needed to retain high allelic diversity in each subpopulation. Reductions in population size have led to the loss of rare alleles in subpopulations of the species. The edge-related decreases in seed germination and poor survival of seedling were also observed in fragmented subpopulations of T. camschatcense (Tomimatsu and Ohara 2004). Integrating demography, reproductive biology, genetics, and life history data under various biotic and abiotic environmental factors and climate change will be crucial for estimating the long term survival of the species (Tomimatsu and Ohara 2010, Ohara et al. 2006). Restoration of extirpated subpopulations requires the identification of natural habitats through niche modelling. Future research should also focus on the collection of data on the extent of available habitat, population decline, and development/refinements of cultivation protocols.