Transient and asymptotic demographics of the riparian species Euptelea pleiospermum in the Shennongjia area, central China

- Transient dynamics is particularly relevant for rare species that colonize ecotones.
- Transient demography of Euptelea pleiospermum was explored to contrast with its asymptotic counterpart.
- Transient population growth rates and eventual population sizes differ sufficiently from asymptotic expectations.
- Vital rates of underrepresented or overrepresented stages have higher elasticities of population metrics.
- Transient envelopes and elasticities reveal some insights bearing critical management implications.

Transient dynamics is a growing concern in population biology and is particularly relevant for rare species that colonize ecotones. Euptelea pleiospermum is a threatened species endemic to eastern Asia and a common component in riparian forests. Transient amplification and attenuation envelopes, as well as elasticities of population growth rates and population momentum, were explored based on stage-structured transition matrix models to articulate the population dynamics of this species. The results demonstrated that transient population growth rates and eventual population sizes (i.e. population momentum) differed sufficiently from asymptotic expectations. But transient population fluctuations as measured by amplification and attenuation envelopes were modest in size. The potential of transient amplification and attenuation are perhaps associated with reproduction of early mature individuals and the mortality of juveniles, respectively. Both asymptotic and transient population growth of E. pleiospermum are most sensitive to survival, less sensitive to tree growth, and largely insensitive to fecundity, whereas the importance of vegetative reproduction is pronounced over fecundity. Underrepresented or overrepresented stages in the initial structure relative to stable stage distribution have comparatively larger elasticities of transient population growth and population momentum, suggesting the importance of vital rates of “biased” stages in driving transient dynamics. Our results highlight the use of transient envelopes and elasticities in guiding the adaptive management for the target species.