Endangered Phoebe bootanica tree populations may face severe habitat contraction and potential distributional shifts under projected climate change in Northeast India.

The present study applies an ensemble of small models (ESM) to assess current and future (2021-2040 and 2081-2100) habitat suitability for the populations of Phoebe bootanica (Lauraceae), an over-exploited timber species endemic to Northeast India's Indo-Myanmar Biodiversity Hotspot. A total of 122 field occurrence records were compiled, of which 22 spatially thinned records were retained for the final modelling, along with 12 environmental variables (including bioclimatic, topographic, edaphic, land cover). Six algorithms (artificial neural network (ANN), classification tree analysis (CTA), generalized additive model (GAM), generalized boosting model (GBM), multivariate adaptive regression splines (MARS), and random forests (RF)) generated bivariate models, which were ensembled via weighted averaging and evaluated using area under the curve (AUC) (0.905), true skill statistic (TSS) (0.745), and the Boyce index (0.795), indicating excellent performance. Elevation (1.56 relative contribution) emerged as the primary driver, favoring altitudes of 1500-2000 m, followed by the precipitation of the driest month (1.47), the warmest quarter (1.35), isothermality (1.33), and soil total nitrogen (1.19). Currently, 1168.58 km2 is highly suitable (> 0.6 habitat suitability index (HSI)), mainly in mid-elevation forests. Under SSP1-2.6, highly suitable area contracts 99.54% by 2040 (to 5.41 km2), recovering slightly to 539.82 km2 by 2100, with the modelled suitable habitat projected to shift from Manipur/Nagaland toward Meghalaya's West Khasi Hills. SSP5-8.5 projects a 92.92% loss by 2040 (82.75 km2), rebounding to 1440.03 km2 by 2100, with a concentration in stable refugia, such as the West Khasi Hills. Moderately suitable habitats decline by 3-51% across the projected scenarios, while not-suitable areas expand by up to 34% in the near future (2021-2040) before contracting by up to 30% by 2081-2100 as habitat conditions partially recover. The ESM approach helped address the constraints of limited occurrence data for this rare species, underscoring Phoebe bootanica's vulnerability to warming/drying trends. Prioritizing mid-elevation nature reserves in regions of niche suitability and persistent refugia is recommended to enhance the species' resilience and sustainable management.