Bidirectional trophic linkages couple canopy and understorey food webs

Abstract

Summary Cross‐system resource flux is a fundamental component of ecological systems. Allochthonous material flows generate trophic linkages between adjacent food webs, thereby affecting community structure and stability in recipient systems. We investigated cross‐habitat trophic linkages between canopy and understorey food webs in a terrestrial, wooded, ecosystem in S outh F lorida, USA . The focal community consisted of three species of A nolis lizards and their prey. We described interspecific differences among A nolis species in the strength and routing of these cross‐habitat flows using stable isotope analysis, stomach content analysis and habitat use data. All three A nolis species in this study consumed different prey and occupied vertically distinct arboreal habitats. Despite these differences, carbon isotope and stomach content analysis revealed strong integration with understorey and canopy food webs for all A nolis species. Modes of resource flux contributing to the observed cross‐habitat trophic linkages included prey movement and the gravity‐driven transport of detritus. Our study shows that terrestrial systems are linked by considerable bidirectional cross‐system resource flux. Our results also suggest that considering species‐specific interactions between predator and prey is necessary to fully understand the diversity of material and energy flows between spatially separated habitats.