Invasion Potential of Calotropis procera (Aiton) W.T. Aiton and Xanthium strumarium L. in the Anthropocene of Ethiopia: Implications for Management

Abstract

The spread of invasive species presents a significant global challenge that threatens natural habitats, agricultural productivity, and biodiversity. In Ethiopia, Calotropis procera and Xanthium strumarium are aggressively invasive noxious weeds whose expansion is intensified by human activities and climate change. This study aimed to model the current and future distribution and habitat suitability of these species across Ethiopia to support effective management strategies. An ensemble modelling approach was employed, combining seven algorithms that include both machine learning and regression-based methods, under various settings with ten replications. Predictions were made for current environmental conditions as well as future climate scenarios projected for the 2050s and 2070s. The results showed that human footprint and bioclimatic variables were the most influential predictors of habitat suitability for both species. Under current conditions, approximately 47,652 and 45,901 km2 were found suitable for Calotropis procera and Xanthium strumarium, respectively, showing a 40% overlap between their ranges. Under future climate projections, suitable habitats are expected to increase significantly, reaching up to 96,629 km2 by the 2070s for Calotropis procera and 57,121 km2 by the 2050s for Xanthium strumarium. These suitable areas are primarily located in the central, northern, southern, and eastern lowlands of Ethiopia and substantially overlap with biodiversity-rich zones and major agricultural regions. The findings highlight that the expansion of both species is mainly driven by human influence, affecting large portions of Ethiopia's lowlands, midlands, and grasslands. To reduce further spread, it is important to implement targeted control efforts along roadsides, highways, and riverbanks, together with community-based weeding campaigns that address various land use systems.