Too early to call it success: An evaluation of the natural regeneration of the endangered Metasequoia glyptostroboides

Metasequoia glyptostroboides is a famous living fossil. It is one of the most successfully recovered endangered species based on the number of extant individuals and the distribution range. However, previous studies have revealed low genetic variation in restored populations. This paper evaluates the natural regeneration ability of the natural and restored populations. The seed masses and germination rates of restored populations were found to be significantly lower than those in natural populations, indicating decreased regeneration ability in the restored populations. The decreased germination rate in the restored populations may be due to inbreeding depression. Very low seed germination rates show that it is very difficult for the restored populations to regenerate naturally, consistent with field surveys. This is the first report on a species that has successfully produced hundreds of millions of individuals but has difficulty in regenerating naturally. Our study highlights the role of population viability analysis in delisting or downlisting species under protection.