Abstract

Understanding how chronic anthropogenic disturbances shape species interactions can enhance our ability to predict biodiversity resilience and guide conservation actions. Securidaca longepedunculata faces various stressors, including herbivory, which can negatively affect plant fitness by reducing growth, survival, and reproductive output. To investigate the impacts of anthropogenic and environmental stressors on herbivory in Securidaca longepedunculata, we conducted a survey of 270 plants across three populations in South Africa. Data collected were analysed by fitting a structural equation model. Our findings indicate that populations of S. longepedunculata closer to human settlements are most vulnerable to anthropogenic pressures, and these pressures seem to promote insect herbivory, which further adds to the stress of the populations. Our findings further indicate that herbivory is intense at high elevations. Although this can be explained under the resource concentration hypothesis, it also fits into the recent general patterns, reporting the highest proportion of plants with glandular trichomes -- known for their contributions to chemical and physical defences against herbivorous insects -- at higher elevations. Overall, our study reveals the extent of a panoply of stressors that constrain the dynamics of the populations of S. longepedunculata. Further studies are needed to investigate how these stressors affect these dynamics.