Genetic diversity and the origin of Taiwania cryptomerioides plantations in South China: implications for conservation and restoration

Understanding the genetic diversity and origin of plantations will support the genetic monitoring and provenance selection in restoration projects and help to enhance the adaptation and resilience of plantation forests under climate change. However, information on the origin and genetic variation for plantations with native tree species is inadequate. Taiwania cryptomerioides Hayata is a threatened tree species and has been used as an important tree species for plantation in montane areas of South China. Information on the genetic diversity and origin of the existing Taiwania plantations is needed to facilitate their further development. In this study, using 12 nuclear microsatellite markers, the genetic diversity and structure were investigated in seven previously assumed natural populations and 19 plantation populations of T. cryptomerioides in South China. The Taiwania plantations showed lower genetic diversity and closer genetic distance than natural populations, indicating that most plantations were established with a narrow genetic basis. The results revealed that the majority of Taiwania plantations originated from two areas of the species’ natural distribution: northwestern Yunnan and southeastern Guizhou. Interestingly, we found that part of plantations in western Yunnan might represent unique genetic resources. Finally, conservation strategies of germplasm resources and genetic guidelines for seed sourcing of T. cryptomerioides are recommended. This study could facilitate the sustainable development of Taiwania plantations and also serve as a valuable reference for plantation management in China and elsewhere. We suggest that genetic monitoring of plantation forests should be considered in future restoration programs.