Taxonomic and geographic selectivity of spermatophytes' extinction risk in China

Concentrating limited resources to protect as many species as possible is the most effective way to improve conservation efficiency, of which identifying the clustering characteristics of species in urgent need of conservation is a prerequisite. In this study, selectivity was used to characterize the taxonomic and geographic clustering characteristics of extinction risk for threatened spermatophytes in China. Results showed that the number of threatened species was highly clustered in taxonomy, floristic regions, and at the county scale. Clustering of threatened species was detected in 18 orders, 53 families, and 201 genera, account for 15.0 %–32.8 % of the total and 52.5 %–71.3 % of the threatened spermatophyte species. 18 out of 57 floristic regions and subregions were over-threatened. 298 counties (10.1 % of China's territory) were over-threatened, covering 83.4 %, 79.3 % and 80.3 % of the total species, threatened species and endemic species, respectively. Counties with the top 10.0 % species richness (SR), threatened species richness (TR) and endemic species richness (ER) covered 79.5 %, 70.3 % and 75.0 % of the total species, threatened species and endemic species, respectively, while covering only 5.7 % of the area of China. More than half of the counties with the top 10.0 % SR, TR and ER, as well as those over-threatened, were outside the existing conservation strategy and action plan. Areas most at risk were also found to be moderately affected by human influence (evaluated by human influence index (HII)) in China. This study provides a new perspective for the study of conservation priority in taxonomic groups and geographical areas.