The combined effects of site susceptibility to invasion and fire on population dynamics of the invasive tree Acacia dealbata

Disturbance by fire can significantly influence the spread and establishment of invasive alien plants, such as Acacia dealbata (silver wattle), which pose serious threats to ecosystems. This study assessed the combined effects of fire count density and landscape susceptibility to invasion on the population dynamics of A. dealbata in the Minho region of Portugal using a mechanistic model. The model, developed using STELLA software, comprises four submodels that address: (A) changing trends in land use and land cover (LULC); (B) fire events; (C) changes in the landscape susceptibility to invasion and (D) A. dealbata population dynamics. Higher fire count densities led to higher A. dealbata population growth and regeneration, increasing landscape susceptibility to invasion. Models such as the proposed approach can help identify potential priority areas for management, namely in sites with low initial structural diversity and continued A. dealbata population growth, as demonstrated in our dynamic simulations. The model not only enhances understanding of interactions between fire and plant invasion dynamics but also provides a tool for predicting the dynamics of other invasive plant species to guide proactive and cost-effective management strategies.