Firmiana danxiaensis H. H. Hsue & H. S. Kiu, a tree species belonging to the Family Sterculiaceae, was discovered and named in 1987. It was listed as a Second Class Protected Key Wild Plant of China in 1999 and in the Conservation Programme for Wild Plants with Extremely Small Populations in China in 2012. It occurs only on Danxia Mountain, a natural World Heritage site in Renhua County, Guangdong Province, southern China, in an area of 168 km2. In 1987, < 100 wild individuals were known. Our investigations in 2014, however, have indicated that the population is c. 10,000 wild individuals. However, the species is threatened as it is a valuable economic species (it is an excellent garden ornamental tree and its trunk is suitable for use in piano construction).
This rare species has low genetic diversity and low population differentiation as a result of its restricted range and the strong selective pressure exerted by the soils of Danxia Mountain, which have a low soil fertility and strong acidity. In October 2011 we collected seeds from the natural population and propagated them at the nursery in Danxia Park. About 300 seedlings had grown to c. 73 cm tall after 18 months. In May 2014, to examine the feasibility of augmenting the natural population of this tree, 45 seedlings were transplanted to the original collection site. Thirty seedlings were also transplanted to the South China Botanical Garden in Guangzhou City (c. 260 km south) and Tianxin Natural Reserve (c. 200 km west) in Lianzhou City. To date, the transplanted seedlings have grown well. Our studies on artificial propagation, reintroduction, and the ecophysiology of this tree will provide a basis for the design of an integrated species conservation plan, including in situ and ex situ conservation, and reintroduction.
