Species distribution modelling of three Aacia species in the Negev Desert: predicting future range shifts and identifying climatic drivers

Sadie Shapiro, Yohay Carmel, Elli Groner 

Climate change is intensifying aridity across desert regions, causing ecological stress and threatening the stability of arid ecosystems. As keystone species are central to ecosystem functioning, predicting shifts in their distribution can provide important insight into broader ecological change. In the Negev Desert, Acacia populations have experienced widespread declines attributed to reduced surface water availability. However, their future persistence remains uncertain due to poorly defined survival thresholds and variability in climate projections. This study applies Species Distribution Modelling (SDM) using MaxEnt to estimate present and future habitat suitability of the three Acacia species in the Negev, Acacia tortilis, Acacia raddiana and Acacia pachyceras, across multiple emission scenarios. Results indicate that suitable habitat for all species may initially expand westwards under mid-century or low-emission scenarios, but contract under higher-emission scenarios later in the century resulting in overall habitat loss. Model outcomes were sensitive to the geographic extent used for model calibration, with broader extents overestimating suitability predictions by failing to capture the local ecological context. Environmental drivers of species’ distributions were assessed using SDMs alongside climatic niche analysis. A. tortilis is a thermophilic specialist restricted to hotter environments, A. raddiana shows broad tolerance across climatic gradients, and the narrow distribution of A. pachyceras appears driven primarily by water availability. Notably, results revealed significant climatic niche similarity between A. tortilis and A. pachyceras despite having non-overlapping geographic ranges, suggesting that non-climatic factors may influence their realised distributions. This study identifies key considerations for improving future predictions of Acacia distributions in the Negev.