Mapping and Modeling the Aerial Extent of <i>Ipomoea Hildebrandtii</i> Across Rangelands in Northern Tanzania

Abstract

This study examines the spatial distribution of <i>Ipomoea hildebrandtii</i> Vatke (purple morning glory), a native invader in the semi-arid rangelands of northern Tanzania whose expansion appears to share important ecological and social dynamics with invasive species worldwide. Using high-resolution PlanetScope imagery (3 m) and a Random Forest classification approach, the study maps species distribution in Simanjiro District and evaluates its association with environmental and anthropogenic factors. Field observations collected in June 2025 supported training data development and image interpretation. The classification model achieved high performance (accuracy = 0.985, AUC = 0.994) and produced a continuous probability surface used to estimate spatial extent and patch structure. Results indicate that I. hildebrandtii occurs in highly fragmented patches across the landscape. Distance to roads emerged as the strongest predictor of occurrence. This relationship suggests that transportation infrastructure is associated with species distribution and may reflect the influence of disturbancerelated processes. Elevation and NDVI showed weaker positive relationships, while other variables were not statistically significant. These findings point to the importance of disturbance in shaping vegetation patterns and suggest that human and livestock movement along road networks may contribute to the expansion of I. hildebrandtii.