Assessing climatic and non-climatic habitat suitability of Haloxylon salicornicum (Moq.) Bunge ex Boiss using ensemble species distribution modelling coupled with analytic hierarchy process

Abstract

Haloxylon salicornicum is a keystone shrub of the Indian arid zone, valued for dune stabilization, fodder, and ecosystem restoration, yet its climatic resilience remains poorly understood. This study assessed the ecological thresholds, current habitat suitability, and future distribution of H. salicornicum under changing environmental conditions. An Ensemble Species Distribution Modelling (ESDM) framework, integrating seven machine learning algorithms with 152 spatially filtered occurrence records, was applied. Predictor variables included bioclimatic, edaphic, land-use, and anthropogenic factors, weighted through an Analytic Hierarchy Process-Multi-Criteria Evaluation (AHP-MCE) to enhance ecological realism. Current suitable habitat occupies ~ 12-15% of the arid zone, primarily in Jaisalmer-Barmer-Bikaner, associated with mean annual temperatures of 18-26 °C, maximum summer temperatures below 45 °C, wettest-quarter precipitation ≥ 80-100 mm, and sandy to sandy-loam soils. Models performed well (AUC ~ 0.98; TSS ~ 0.94). By 2070, total climatically suitable habitat for H. salicornicum is projected to contract by approximately 40-50% under RCP 8.5, whereas the optimum suitability zone (after accounting for edaphic and anthropogenic constraints) decreases by about 12% whereas. RCP 4.5 suggests relative stability with modest north-westward expansion. Incorporation of AHP-MCE highlighted that, while climate primarily determines potential range, soil properties, vegetation structure, and urbanization substantially constrain realized distributions. This represents the first predictive framework for H. salicornicum in India, identifying persistent refugia in western Rajasthan as priority zones for conservation and restoration. The integrated ESDM-AHP approach demonstrates that climatic thresholds define potential distribution, but non-climatic filters regulate establishment, offering crucial insights for climate-resilient shrubland management, agroforestry planning, and long-term desert restoration in arid landscapes.

Keywords: Haloxylon salicornicum; Arid land restoration; Bioclimatic and edaphic predictors; Climate change scenarios; Ensemble species distribution modelling (ESDM); Habitat suitability mapping.