4.1. Conifer richness and conservation priority
Our results showed that the major centres of conifer diversity and endemism were located in Sichuan and Yunnan Provinces (Farjon & Filer, 2013) including Qionglai-Minshan ecoregion which is the major centre of threatened and endemic conifers, and this finding supports the global assessment of this ecoregion “critically endangered” due to high level of threats e.g. tourism, logging and overgrazing (López-Pujol & Zhao 2004; Ye et al.2015; WWF 2018). Furthermore, the threatened conifers in Hengduan Mountains, are facing high risk of extinction due to the decline of their populations (Threatened Conifers of the World 2019; Farjonet al. 2019) and this support the suggestion of conservation priority for these regions which are rich in neo- and palaeo-endemic flora at the family and genus levels (López‐Pujol et al. 2011; Huang et al. 2016). In details, conservation priority should be given to the threatened and/or endemic conifers distributed inside the ecoregions: Qionglai-Minshan and Hengduan Mountains e.g. Picea likiangensis , Picea aurantiaca, Picea brachytyla , Larix potaninii , Abies recurvata , Abies fabri , Abies forrestii , Abies squamata, Juniperus spp., Pinus henryi, and Pseudotsuga sinensis (Farjon et al. 2019; Dakhil et al. 2019; Threatened Conifers of the World 2019). Similarly, Nujiang Langcang Gorge ecoregion harbour high richness of endemic and threatened conifers which highly threatened by logging (Ye et al. 2015; WWF 2018). Conservationists should give more attention and priority to the IPAs and conifers of this ecoregion e.g. Abies delavayi, Taxus wallichiana, Pinus densata, Pinus yunnanensis, Taiwania cryptomerioides, Cupressus duclouxiana ( Ye et al. 2015; Threatened Conifers of the World 2019; Farjon et al. 2019).
The highest richness of conifers found at latitude ranged from 28° to 33° indicating to Sichuan-Yunnan hotspot of conifer diversity and endemism (Farjon 2010; Farjon and Filer 2013), and this finding strongly agrees with the results of Fragniere et al. (2015) who studied the global latitudinal distribution of gymnosperms (607 conifer species). Moreover, the highest elevation is also found at that latitudinal range compared to the other global regions in which conifers present (Fragniere et al. 2015). Hence, the findings of Fragniereet al. (2015) could be assumed as a validation for our output of richness which generated by SDM toolbox (Brown 2014).