Auxiliary Seed Treatment Is Necessary to Increase Recruitment of a Critically Endangered Species, Abies beshanzuensis (Pinaceae)

Disordered germination is widely observed in plant species with extremely small populations (PSESPs) in China. Abies beshanzuensis M. H. Wu, a PSESP (with only three extant adults in Zhejiang Province, China) that also has poor seed germination in the field, belongs to the Pinaceae family. Pinaceae generally tend toward symbiosis with ectomycorrhizal (ECM) fungi to alleviate climate change-induced stresses. Therefore, exploring how to improve seed germination of A. beshanzuensis and whether it is an ECM species will contribute to increasing recruitment for conducting further conservation research. In this study, four temperature regimes (10/15 degrees C, 15/20 degrees C, 20/25 degrees C, and 25/30 degrees C) were selected to explore the response of seed germination to rising temperature. Based on the microscopic features of fine roots, together with molecular techniques, the mycorrhizal type of this species was identified. The seed germination of A. beshanzuensis was increased from 1-2% to around 4.5% by 14-day cold stratification and under 20/25 degrees C fluctuating temperature conditions. Our findings indicated that A. beshanzuensis may be endangered as a result of insufficient seedling recruitment due to poor germination under the current climate. A. beshanzuensis was confirmed as an ECM fungi-associated tree species. This study highlights the necessity of incorporating auxiliary seed treatment into population recovery programs of A. beshanzuensis, thereby better conserving the species under ongoing environmental changes.

Automated summary

Disordered germination is observed in the plant species Abies beshanzuensis, which has a very small population and poor seed germination. This study explores the response of seed germination to rising temperature and identifies the mycorrhizal type of this species. The results show that cold stratification and fluctuating temperature conditions can improve seed germination, and the species is confirmed to have a symbiotic relationship with ectomycorrhizal fungi. The findings highlight the necessity of incorporating auxiliary seed treatment into population recovery programs for better conservation of the species.