2.1. Species distributional data and richness estimation
We downloaded the occurrence data from the Global Biodiversity
Information Facility (http://www.gbif.org), Chinese Virtual Herbarium
(http://www.cvh.org.cn), National Specimen Information
Infrastructure (http://www.nsii.org.cn/), and appropriate
literature. We cleaned many records by removing synonyms and unresolved
names to obtain the accepted names from conifer database (Farjonet al. 2019). Geographical records outside the study area and the
duplicates were deleted using ArcGIS 10.3 (ESRI). Finally, we compiled
8,962 occurrence records of 97 taxa including 59 endemics, 63
threatened, and 41 endemic-threatened species (Table S1, Appendix A).
Species richness was calculated as the total number of species per grid
cell (50 × 50 km2) using the SDM toolbox in ArcGIS 10.3 (Brown 2014).
Several studies used the same grid size (e.g., Wang et al. 2010;
Liu et al. 2017; Shrestha et al. 2018; Liu et al.2018b). The generated richness maps were projected to “WGS 1984 UTM
zone 48 N” and comprised 516 grid cells (Appendix B). We used five
conifers’ ecoregions defined by WWF (Olson et al. 2001; WWF
2018).