7 Carpobrotus as a case study of the complexities of species impacts

Abstract

This chapter presents a discussion of one invasive plant species that is believed to act as both an autogenic and an allogenic engineer potentially influencing resident species composition and ecosystem processes through any of several pathways. Species such as C. edulis are of conservation concern because very few resident species appear to co-exist with them and they have the potential to affect other trophic levels. Carpobrotus edulis was introduced because of its ability to engineer the soil, yet its affect on soil stability is probably not the reason why it is having such a large impact on resident species. Its impacts do, however, likely relate to the very dense rooting structure it creates and its influence on the soil environment, as well as its ability to modify aboveground structure. If such an invader is removed, its impacts will not be as readily reversed as those of an invader whose impacts are largely the result of aboveground structures. Such comparative studies of invader impacts and reversibility of impacts could prove insightful to the understanding ecosystem development in a conservation and restoration context.