Role in ecosystems

Abstract Tortoises effectively “engineer” their habitats, and tortoise population declines can have cascading consequences throughout ecosystems. This chapter explores the role of Galapagos giant tortoises (Chelonoidis spp.) in the ecosystems that they inhabit. The chapter begins with a review of the interactions that tortoises have with plants, including herbivory, trampling, and seed dispersal. This is followed by an investigation of how these interactions accumulate to affect the distribution and ecology of other plant and animal species. Understanding ecosystem engineering effects of these “mega-herbivores,” and how they differ from those of introduced, nonnative herbivores, is a vital component in the conservation and restoration of fully functioning ecosystems within the Galapagos Islands.