We are conducting a nutrient addition experiment within KLEE to investigate how nutrient cycling responds to the long-term exclusion of different large herbivore guilds, in combination with the presence or absence of cattle, and how this in turn structures the plant communities within the KLEE plots. This integration represents a rare experimental opportunity to disentangle how distinct herbivore guilds, from megaherbivores to livestock, affect patterns of nutrient limitation and soil nutrient dynamics, plant community composition, and aboveground productivity in a savanna ecosystem, and explore the interactions between biotic and abiotic drivers of ecosystem functioning.
Beginning with pre-treatment data collection in 2023, we implemented the full factorial nutrient addition treatments in early 2024, for a total of 75 plots across the KLEE experiment. Our team, which has included graduate students Carmen Watkins and Sarah Ortiz and KLEE plant experts Mathew Namoni and Jackson Ekadeli, conducts annual measurements of aboveground biomass, species cover, and light availability. In addition to KLEE-specific questions, these data will contribute to the Nutrient Network globally distributed experiment, in which African sites are highly underrepresented.
This experiment addresses pressing questions at the intersection of global change, biodiversity loss, and nutrient cycling, and provides a framework for a broad range of other research questions. These include understanding the role of herbivores in determining rates of nitrogen fixation in legumes, which in turn determine the amount of new N entering the ecosystem. In addition, these plots provide a framework for understanding the association between soil microbes and soil nutrients, and plant communities, linking mammalian communities to microbial functioning. Collectively, this research will help us understand the interplay between biotic and abiotic factors that influence ecosystem services, such as forage quality and quantity, in arid and semi-arid rangelands.
Universities: University of Texas at Austin, University of California – Davis, Karatina University, Egerton University, the University of Notre Dame
Principal Investigators: Dr. Amy Wolf