Reintroduction of Hopea hainanensis Merr. and Chun, a Wild Plant with Extremely Small Populations, in Southern China

Abstract

Hopea hainanensis Merr. and Chun (Dipterocarpaceae) mainly distributes in the tropical lowland rain forests in Hainan Island and northern Vietnam. Population size of this species decreased greatly in recent years because of extremely high value in the timber market. Thus H. hainanensis is listed as an endangered species in the IUCN Red List of Threatened Species 2018 and the list Wild Plants with Extremely Small Populations in China in 2012. The germination rate of seeds is high after removing the seed wings. Thus, the materials for reintroduction are relatively abundant. We conducted reintroduction experiment in 2017 from August to September. The 3-year-old seedlings of H. hainanensis were planted in the understory of the 60-year-old secondary forest after thinning treatment or without any silviculture management. A total of 9332 individuals of H. hainanensis were planted. After transplantation, all individuals were tagged and measured in December 2017. Then all seedlings were re-censused in December 2018 and December 2019. Results showed that 91% of the seedlings were still alive after 2 years of transplantation. Moreover, the survival rate of reintroduced seedlings was higher after thinning treatment (93.6%) than that of control (88.5%). The long-term monitoring is still needed for assessing the effect of thinning treatment on reintroduction in the understory of the secondary forest.