Some animals play disproportionate roles in ecosystems relative to others. Often termed ecosystem engineers, these animals can shape the structure and functioning of landscapes in profound ways. Much of our work on these animals has focused on termites and elephants in African ecosystems. Future work on animal-driven ecosystem engineering includes planned studies on white and black rhinos, as well as hippos, in an effort to integrate the effects of multiple megaherbivores into our understanding of how landscapes look and function.
Termites
Termites are arguably the most important soil organisms in tropical and sub-tropical environments, where they facilitate a majority of litter decomposition and alter the nature and properties of soils through their foraging and mound building activity. Their activity also leads to nutrient concentrations in their nests, often in the form of large epigeal mounds, which results in nutrient hotspots across the landscape. The vegetation communities on termite mounds are often very different to the vegetation in the surrounding matrix, due to the increased nutrients as well as increased moisture on and around mounds. These differences increase landscape heterogeneity and have cascading effects on invertebrate communities, mammalian foraging patterns and fire regimes. Our work seeks to better understand these termite-driven effects and to quantify their magnitude and importance for ecosystem functioning at landscape scales.
Elephants
Elephants, when present, are among the strongest drivers of vegetation change in African ecosystems, altering patterns of treefall, vegetation cover and aboveground carbon stocks. Elephants also serve as a model organism for understanding the role of megafauna and provide clues as to how the now largely extinct megafauna of other continents shaped how these ecosystems look today. Our work on elephants seeks to quantify their role in driving vegetation change across landscapes in both savanna and thicket habitats, as well as to understand how they interact with other species shapes landscapes.
Image courtesy of Antoine Marchal