Researchers collect Thuja sutchuenensis seeds from a cliff at Xuebaoshan Nature Reserve in Chongqing on October 16, 2023. Photo: Courtesy of Wang Xiaoyu

Guo Quanshui celebrated his 70th birthday at the Xuebaoshan Nature Reserve in Southwest China's Chongqing Municipality.  

This retired researcher from the Chinese Academy of Forestry is a "research fanatic." From his 50s to his 70s, Guo led the Chinese Academy of Forestry research team in tackling the Thuja sutchuenensis challenge, even moving his lab to the mountains.

"The wild Thuja sutchuenensis population has a narrow distribution area, small total numbers, poor growing environments, and long natural growth cycles... Without finding ways to expand reproduction, it still faces the risk of extinction due to extreme weather or disasters," Guo Quanshui said.

The Thuja sutchuenensis was listed as one of the 50 Plant Species with Extremely Small Populations (PSESP) for rescue protection during China's 14th Five-Year Plan period (2021-25). National Key R&D Program of China, National Forestry and Grassland Administration wildlife protection projects, National Natural Science Foundation youth fund projects, Chongqing Municipal Finance Program for the Rescue and Conservation of Wild Plant Species with Extremely Small Populations... Support from all levels enabled Thuja sutchuenensis protection efforts to take on the challenge of artificial propagation, consolidate existing numbers, expand new growth, and forge a new path.

Every year after spring arrives, research teams, reserve staff, and surrounding farmers work day and night on cuttings.

Collecting panicles on rainy days to prevent water loss; within 12 hours, trimming the cut at the base of the panicle into a horseshoe shape, then treating with a fungicide and rooting powder, and carefully inserting into the growing medium…

Guo led the team to tackle key problems in Thuja sutchuenensis seeding and cutting propagation technical procedures. The rooting rate of cuttings, less than 20 percent 10 years ago, now reaches 96 percent.

Xuebaoshan has built four Thuja sutchuenensis breeding bases, 18 intelligent seedling greenhouses, and a 420-acre Thuja sutchuenensis scion garden. The Thuja sutchuenensis National Forest Germplasm Resource Library is located here. Breeding and reintroduction techniques are also rapidly promoted in habitats like Chengkou and Xuanhan.

Southwest University, the Chongqing Academy of Chinese Materia Medica, and other universities and institutes have collaborated to create a large-scale breeding research platform for rare and endangered plants, the first of its kind in Southwest China, with Xuebaoshan Reserve as the main body. Well-informed locals have joined in, allowing experts and local people with relevant knowledge to join forces.

Currently, the wild Thuja sutchuenensis population has recovered to over 10,000. Nearly a million artificially bred Thuja sutchuenensis trees have been reintroduced to the wild, with a reintroduction area exceeding 4,500 acres, and they have achieved comprehensive natural reproduction. The number and scope of their wild reintroduction marks a pioneering moment in the history of rare and endangered plant reintroduction in China.

In March, Thuja sutchuenensis protection technology was selected into the National Forestry and Grassland Administration's "2024 Top Ten Advances in Chinese Forestry and Grassland Science and Technology," evaluated as "providing a Chinese case for global endangered species protection."