Faculty Member - Division of Biological Sciences University of Missouri-Columbia

A) Some of the dominant factors driving vegetation dynamics in the Serengeti ecosystem; B) Observed and modeled wildebeest migration route (shown as the centroids for the entire herd) over a three-year period in the Serengeti ecosystem (Serengeti NP is inset).

Research description

I am interested in a range of questions in community ecology, primarily in the area of herbivore-fire-plant interactions. A common theme in my work is the role of plant-animal interactions as a force structuring both herbivore and plant communities.

Some current research questions include: 1) How do mammalian herbivores interact with fire to determine tree-to-grass ratios in savannas? 2) How will climate change-induced shifts in plant communities affect herbivore populations and movement behavior over time? 3) What is the role of predation and disease on herbivore-plant dynamics? 4) How do herbivores and fire alter ecosystem function, e.g., the N and P cycles and soil moisture dynamics? I explore these questions at spatial scales that range from individual organisms to landscapes, with most of my research focusing on savanna ecosystems in East and Southern Africa.

I use both theoretical and empirical tools in my work. My primary approach is to develop mathematical and computer simulation models that can be parameterized with and validated against large data sets. Data for these models are provided by remote-sensing and GIS products, literature sources, and my own field work, which includes natural and field experiments. Beyond my core interests in community ecology, I am broadly interested in developing improved modeling and statistical tools for linking theory and data in all areas of biology.

Selected publications

Holdo, R.M., Holt, R.D., Galvin, K., Polasky, S., Knapp, E., and Hilborn, R. 2009. Responses to alternative rainfall regimes and antipoaching enforcement in a migratory system. Ecological Applications, in press.

Holdo, R.M., Holt, R.D., and Fryxell, J.M. 2009. Opposing rainfall and nutrients gradients best explain the wildebeest migration in the Serengeti. The American Naturalist 173:431-445

Holdo, R.M., Holt, R.D., and Fryxell, J.M. 2009. Grazers, browsers, and fire influence the extent and spatial pattern of tree cover in the Serengeti. Ecological Applications 19:95-109.

Holdo, R.M. 2007. Elephants, fire, and frost can determine community structure and composition in Kalahari woodlands. Ecological Applications 17:558-568.

Holdo, R.M., Holt, R.D., Coughenour, M.B., and Ritchie, M.E. 2007. Plant productivity and soil nitrogen as a function of grazing, migration, and fire in an African savanna. Journal of Ecology 95:115-128.

Holdo, R.M. 2006. Elephant herbivory, frost damage, and topkill in Kalahari sand woodland savanna trees. Journal of Vegetation Science 17:509-518.