Multiple Environmental Determinants of Opuntia stricta Distribution: Habitat Suitability Across Global Biomes

Opuntia stricta is a highly invasive cactus species that threatens arid and semiarid ecosystems worldwide. We identified the optimal species distribution model (SDM) to predict its global habitat suitability using three hierarchical frameworks: climate only, climate with soil, and climate with soil and human influences. Among five modeling algorithms, Maximum entropy (MaxEnt) showed the highest predictive performance, supporting its use as the primary habitat-suitability model. Habitat suitability was driven mainly by climatic variables, with precipitation of the driest month, isothermality, and potential evapotranspiration contributing 30.7%, 26.7%, and 18.3%, respectively, whereas soil and human factors made smaller contributions. Biome-level analysis revealed that Mediterranean ecosystems exhibited the highest proportional habitat suitability (48.5%). The climate-only model predicted 7.35% of global land as suitable, which decreased by 34% after soil and human variables were incorporated. Native-introduced niche-overlap analysis further showed that additional environmental predictors refined environmental niche characterization across modeling scenarios. These findings highlight the importance of integrating multiple environmental predictors to improve habitat-suitability predictions and provide a robust framework for supporting the management of O. stricta and other invasive plant species worldwide.