Conservation status of Primulaceae, a plant family with high endemism, in China

Primroses, approximately 1000 species from the family Primulaceae, are mostly distributed in subalpine to alpine areas and attract attention due to their high ornamental value. However, they have been increasingly threatened by human activities and climate change in recent decades. China harbours 535 primrose species from 12 genera, most of which are endemic. In this study, we established a distribution database of the primroses in China, then explored the geographic pattern of the richness of primrose species in relation to environmental factors and evaluated their conservation status. The results showed that the primrose richness was highest in the mountainous areas from the eastern Himalayas to the Hengduan Mountains, with habitat heterogeneity (explaining 37.6% of the variance) and temperature seasonality (26.0% of the variance) together explaining this pattern. Furthermore, the richness of endemic and threatened primroses had been strongly affected by the long-term climate change since the Last Glacial Maximum. On average, national nature reserves (NNRs) covered 29.5% of the distribution areas of primroses. However, there were still 97 less-protected species, each of which had a distribution area <2000 km2 covered by NNRs. By analysing this group, we proposed that nature reserves need to be established in several conservation gaps mainly located in Southwest China to protect the primrose species in China.