Northward shifts and range contractions: future distribution of Plicosepalus acaciae in Vachellia woodlands of AlUla, Saudi Arabia

Parasitic plants such as Plicosepalus acaciae act as keystone species but can exacerbate host stress under warming and drying conditions. To inform adaptive woodland management, this study models the current and future potential distribution of P. acaciae under climate change scenarios in AlUla, Saudi Arabia. The maximum entropy model was used to analyze a dataset of 124 georeferenced occurrences collected between March 2023 and April 2024. Nineteen bioclimatic variables were used as predictors of habitat suitability. Additionally, these variables, together with topographic factors and host preference, were employed to generate a most limiting factor map using DIVA-GIS. The model performed strongly (AUC = 0.847; TSS = 0.66), identifying annual mean temperature (17–19 °C), precipitation in the wettest month (> 18 mm), and altitude (200–800 m) as key determinants of current habitat suitability. At present, P. acaciae predominates in wadi and mountainous habitats, while sandy areas and high-elevation plateaus remain unsuitable. Future projections under RCP 2.6 and RCP 8.5 scenarios show pronounced range contractions across central and southern AlUla by 2050 and 2070, accompanied by a potential northward shift. These findings underscore P. acaciae ’s vulnerability to increasing aridity and thermal stress, with its survival dependent on microclimatic stability, host availability, and disperser behavior. Results offer valuable insights for developing climate-resilient management strategies aligned with the Royal Commission for AlUla’s ecological restoration goals—such as prioritizing high-suitability subregions, establishing host-specific monitoring programs, integrating avian disperser ecology into management planning, and incorporating trait-based variables and Shared Socioeconomic Pathways (SSPs) into future modeling.