A multifaceted approach to expanding conservation efforts in the Pan-Himalayan landscape

The Pan-Himalayan biogeographic domain is a significant region for biodiversity conservation and climate resilience. This region has both tropical and extratropical flora and holds ecological, cultural, and socio-economic importance. However, knowledge about the spatial distribution and threats to threatened plant species in the study area is still poorly known. In this study we evaluate the phylogenetic diversity and phylogenetic endemism of threatened flora in the region, and also examine the effect of rapid land cover transformation and landscape fragmentation between 2000 and 2020 on the preservation of distinct evolutionary lineages. Phylogenetic metrics provide a better understanding of ecological, historical, and evolutionary factors that shape plant communities in highly biodiverse regions. Our result show that current protected areas are insufficient for preserving Pan-Himalayan biodiversity, and also reveal a significant gap in conservation efforts within these areas. We highlight conservation priorities areas in the western Himalayan belt encompassing 2.43 million km(2) and covering 26.73% of the total area. However, a large conservation gap encompassed 22.67% (2.06 million km(2)) hotspots of total study area, whereas non-hotspot priorities covered 67.62% (0.77 million km(2)) of the total protected area, revealing a mismatch between biodiversity hotspots and protected areas. In addition, biodiversity priority areas have been threatened by rapid land cover transformation and landscape fragmentation between 2000 and 2020. There were 6.93% increase in cropland area and 172.64% increase in impervious surface, while an increase in landscape fragmentation and a decrease in landscape cohesion in different hotspots within protected areas. The biodiversity hotspot regions emphasize the need to conserve unique evolutionary lineages and high species occurrence areas with targeted conservation strategies. Mountainous, but cross-border international cooperation is highly recommended for effective preservation strategies. Our study has implications for advancing biodiversity preservation and sustainable ecosystem management not only in the Pan-Himalayan but also in similar regions, as well as for achieving the 2030 protection goal.