Background: Knowledge of plant population structure facilitates conservation, management, and utilization of endangered plants. Research question: What is the current status of the natural populations of Tetracentron sinense in Leigong Mountain Nature Reserve (LMNR) and what future population development trends can be predicted? Studied species: Tetracentron sinense  Study site and period of research: T. sinense populations in LMNR in China in 2018. Methods: The population structure and quantity dynamics of four typical patches were studied using static life tables, survival curves, survival analyses, and time series analyses.  Results: The age structures of the T. sinense populations were spindle-shaped, with few seedlings and saplings, and Deevey type II and Ⅲ survival curves. The mortality rate (qx) of each patch increased quickly, and then plateaued, finally increasing again. Survival rate (Sx) showed a contrary trend to qx. Trends in cumulative mortality rate (F(i)), killing power (Kx), mortality density (f(ti)), and hazard rate (λ(ti)) with increasing age class were similar: increasing at a younger age, gradually stabilizing in middle age, and then increasing slightly in older age. The number of individuals in these T. sinense populations was predicted to decrease sharply in future, with younger individuals being seriously deficient. The results showed that the natural populations of T. sinense in the LMNR were relatively stable but were in an early stage of decline.  Conclusions: The lack of younger individuals might reflect a bottleneck for regeneration of T. sinense populations, leading to a decline in population size.

Using data from the Qing dynasty, we investigate the long‐run impact of early development on today's living standards in China. We use city‐level population density in 1776 as a measure of early economic prosperity, and examine how it is associated with today's development indicators such as the average night light density, GDP per capita, average years of schooling, and trade openness. We find that cities which were more prosperous during the Qing dynasty are now also brighter, richer, more educated, and more open.

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Tetracentron sinense Oliver, as a tertiary living fossil, a dramatic decline in T. sinense population amounts, genetic resources depletion and recent human activities have shaped habitat fragmentation of relict and endangered plants, although there is ample evidence of its great medicinal, economic and ecological value. However, little is known about the genetic evolution of T. sinense. With this work, 193 individuals from 22 natural T. sinense populations regarding its genetic diversity, genetic differentiation, and demographic history using simple sequence repeat (SSR) markers to clarify its evolution models and develop scientific conservation strategies. We evaluated the genetic diversity, population structure and demographic history of 193 T. sinense individuals based on 14 SSR markers. At the species level, PPL, I and He were 100%, 1.631 and 0.559, respectively. At the population level, Na, Ne, I, Ho and He were 3.221, 2.505, 0.937, 0.434 and 0.566, respectively. The results revealed high genetic diversity at the species level and within populations. Individuals were structured into three main clusters (K = 3) with significant genetic differentiation (Fst = 0.31). Demographic history analysis showed that T. sinense differentiated according to the radial differentiation model. The differentiation occurred 1.115×104 to 2.23×104 years ago during Last Glacial Maximum. The twenty–two T. sinense populations revealed moderate genetic diversity and seemed to be structured into three clusters with high differentiation suggesting its preserved the evolutionary potential and the Hengduan Mountains and Qinling Mountains act as the two major glacial refuges. High differentiation caused by long–term geographic isolation may lead to the population extinction. The radial differentiation model suggested that T. sinense originated from common ancestor.