UC Santa Barbara

The Anthropocene is characterized by profound human-mediated effects on biodiversity loss and climate change. These two phenomena are traditionally studied as separate, yet parallel processes. However, today it is clear that wildlife, and large-bodied wildlife in particular, have significant impacts on carbon storage and cycling in ecosystems worldwide. It is increasingly necessary to incorporate large-bodied animals into characterizations of the carbon cycle to better predict the possible outcomes of their loss on climate. I first asked how large, wild herbivore species and their experimental loss influence a range of essential ecosystem processes with a global review and analysis. I focused on ecosystem carbon dynamics with a meta-analysis, parsing data on metrics of carbon storage or cycling from all published studies that use large-scale, large herbivore exclosure experiments. Using conclusions from this study, I narrowed my scope for empirical research on a single exclosure experiment located in Laikipia, Kenya: the Kenya Long-term Exclosure Experiment (KLEE). KLEE has been operating since 1995 in a savanna ecosystem where a robust community of large-bodied herbivores (and which share the landscape with domestic cattle) persists. I used classic soil science methods and developed new tools to monitor soil carbon storage and rates of cycling, in a range of experimental herbivore treatments simulating large herbivore loss and their spatial replacement with domestic cattle. My analyses explore the indirect effects of these large bodied herbivores on ecosystem carbon, via their direct effects on savanna structure and assembly. Understanding the outcomes of large herbivore losses on landscape scales like those simulated in KLEE will add necessary context-specific nuance to predictions of how continued large herbivore losses will impact carbon budgets globally.