Reintroduction of Bretschneidera sinensis Hemsl., an Endangered Endemic Tree

Here, we describe ongoing, successful conservation efforts for the tree species, Bretschneidera sinensis Hemsl., led by South China Botanical Garden. B. sinensis is a dioecious, deciduous tree species with a limited range in the subtropics of Vietnam, Thailand, and Southern China. It comprises the sole species within Bretschneideraceae (Brassicales). The species is a relict of the ancient boreotropical flora and exhibits a classic pattern of biodiversity distribution, in which some species-poor Asian endemic lineages had wider distributions in the Northern Hemisphere during the Cenozoic. The status of this species as a relict and its dioecious life history and extrinsic, anthropogenic factors likely all contribute to its rarity and, consequently, its rating as “endangered” by the International Union for Conservation of Nature and “category I protected” by the Chinese government. At South China Botanical Garden, we have led efforts to conserve this species through theoretical and applied research as well as public outreach and policy recommendations. In particular, we have successfully germinated over 6000 seedlings of this species representing six natural populations, and we have introduced 500 of these seedlings into Nankun Mountain Natural Reserve to reinvigorate the existing population there. Seedlings also exhibit healthy development in cultivation at South China Botanical Garden. Therefore, we recommend to continue and improve upon our integrative restoration plan for this species, through which we will lead in situ and ex situ conservation efforts alongside public outreach and education, simultaneously seeking input from stakeholders and providing local and national policy recommendations. We believe that B. sinensis has great horticultural potential due to its wide ecological tolerances and attractive foliage, fruits, and flowers and also comprises an important model for evolutionary research, due to its classic pattern of biodiversity distribution.