Across the globe, wildlife and livestock share much of each others’ landscapes, but most wildlife research is carried out in protected areas. Livestock often compete with wildlife, and can have other (mostly detrimental) effects on ecosystem functions, especially at high densities. We report here on results from the Kenya Long-term Exclosure Experiment (KLEE), designed to tease apart the separate and combined effects on a savanna rangeland of livestock, wildlife, fire, and drought/seasonality. For the past 25 years, we have been manipulating the presence and absence of cattle, meso-wildlife, and mega-herbivores (elephant and giraffes) in 18 four-hectare plots in Laikipia, Kenya. We regularly measure vegetation, dung deposition (vertebrate use), and soil chemistry.
Results/Conclusions
One of our most striking set of results is that elephants reduce many of the impacts of cattle on this system. The impacts of cattle that are mitigated by elephants include 1) decrease in grass cover, 2) decrease in habitat use (competition) by multiple species of wildlife, 3) increase in primary productivity, 4) decrease in soil nitrogen and phosphorus, 5) bush encroachment, and perhaps 6) decrease in rodent populations, and 7) increase in termite abundance. One cause of these mitigations is that cattle remove less grass in plots accessible to elephants, likely because of an elephant-induced shortage of N-rich forage. However, there may be other pathways of mitigation as well, including reductions in tree densities by elephants. These results are a subsample of the rich, complex, and often unexpected patterns that are being revealed by an experimental design that crosses multiple interacting stressors (e.g., multiple herbivore guilds, fire, livestock intensity, soil fertility, and drought cycles).