Data for: Apex predator suppression is linked to altered recruitment and size structure of a foundational desert tree

Trophic cascades are typically conceptualised as three-link systems in which apex predator suppression increases herbivore pressure and reduces plant recruitment. However, in four-link systems that include mesopredators, predator suppression may instead decrease browsing pressure, with contrasting consequences for plant populations. Despite this theoretical distinction, empirical evidence linking alternative trophic configurations to long-term plant population structure at landscape scales remains limited. We examined how variation in trophic configuration influences the demography of mulga (Acacia aneura), a dominant and long-lived arid-zone tree. We compared historical and contemporary mammal assemblages and mulga density and size distributions in Australia across regions where dingoes (terrestrial apex predator) were common or rare, while accounting for livestock grazing pressure. To identify demographic mechanisms, we conducted an in-situ seedling survival experiment and parameterised a size-structured population model to simulate long-term responses to browsing intensity. Where dingoes were common, mesopredators were less abundant, rabbits were more abundant, and the survival of mulga seedlings was lower. Areas where dingoes were common were also characterised by lower tree densities and stands dominated by larger individuals. In contrast, where dingoes were rare, higher seedling survival was associated with greater stand densities and a shift toward smaller size classes. The size-structured model reproduced these differences, illustrating how sustained variation in early-life survival can generate persistent shifts in population structure. Our results provide landscape-scale support for the plausibility of a four-link trophic cascade triggered by the suppression of dingo populations that can produce opposing demographic outcomes in a long-lived woody plant. By integrating comparative data, field experimentation, and demographic modeling, we show how context-dependent trophic cascades could regulate tree recruitment and size structure, with implications for carbon storage in arid ecosystems. Our results underscore the importance of expanding our thinking on trophic cascades beyond three trophic links. We propose that analogous trophic cascades with more than three links and vegetation shifts may occur across regions where apex predators are lost but remain underappreciated; not because predators’ effects are trivial, but because of the rarity of intact reference sites and inherent difficulties involved in understanding complex networks of interspecific interactions that occur in ecosystems.