Ensemble species distribution modelling of climate change impacts on the distribution of Pinus krempfii in Vietnam from the Last Glacial Maximum to 2070

Tropical montane endemics are among the taxa most threatened by climate change, yet quantitative assessments of their past and future range dynamics remain scarce. Here we present the first ensemble species distribution modelling (SDM) assessment for Pinus krempfii , an Endangered flat-needle pine endemic to the Central Highlands of Vietnam, integrating seven algorithms, eight uncorrelated bioclimatic variables, five CMIP6 global circulation models and two emission scenarios (SSP1-2.6, SSP3-7.0), with hindcasting to the Last Glacial Maximum (LGM, ~21,000 yr BP). Our results reveal that suitable habitat has already contracted by ~68% from the LGM to the present and is projected to decline by a further 57.6% (SSP1-2.6) to 71.1% (SSP3-7.0) by the 2070s, with some GCMs projecting near-complete habitat loss. Temperature seasonality (bio4) and minimum temperature of the coldest month (bio6) emerged as the primary climatic determinants, highlighting the species’ sensitivity to both thermal variability and cold-season regimes. The median elevation of suitable habitat rose from 933 m (LGM) to 1,304 m (present) and is projected to reach 1,490–1,528 m by the 2070s, a ~600 m upslope shift since the LGM. Critically, approximately 40% of current suitable habitat falls within existing protected areas, and the Lang Biang Plateau and Chu Yang Sin massifs are identified as persistent climate refugia under all future scenarios. Our findings demonstrate that narrow-range tropical conifers can face compound extinction risk from both post-glacial legacy and anthropogenic warming, that protected-area networks can partially buffer this threat, and that multi-GCM ensemble SDMs are essential for capturing the inter-model uncertainty in conservation planning. To prevent further range loss, we recommend expanding protected areas in the Lang Biang and Chu Yang Sin massifs and implementing assisted migration strategies for this conservation-dependent species.