Consumer-driven nutrient impact in savannas and the role of species diversity

To what extent are nutrient landscapes influenced by animal action? Large mammals eat, defecate and die, and they do so in different locations. What is more, herbivorous mammals require nutrients in very different ratios to that supplied by their vegetation food source. So the nutrient ratios originally consumed differs greatly from those eventually excreted. Thus large mammals should be depleting, replenishing, transporting and reshaping nutrient landscapes as they go. Are these impacts generic across species or does it matter which species are involved? How might predators modify these impacts and how do predator-invulnerable megaherbivores counteract involvement by predators? To what extend does human action interfere with these animal-mediated nutrient flows?

These are the kinds of questions that motivate our work and that we will be exploring during this seminar. Our work draws on elements from the fields of community and ecosystem ecology, predator-prey dynamics, animal behaviour and ecosystem stoichiometry. We focus on African savanna landscapes where we have designed a series of small-scale field experiments which we combine with larger-scale agent-based modelling studies to explore the impact of large mammals on nutrient landscapes and the nutrient consequences of species extinction and restoration.