2nd UF Water Institute Symposium Abstract

Submitter's Name Gloria Perez-Falcon
Session Name Poster Session: Hydrologic, Biogeochemical and Ecological Processes 2
Category Hydrologic, biogeochemical and ecological processes
Poster Number 234
Author(s) Gloria Perez-Falcon,  UF-Dept of ABE
  Greg Kiker,  UF - Dept. of ABE
  Rafael Munoz-Carpena, UF - Dept. of ABE
  Modeling Landscape Processes to Explore Water as a Limiting Factor in Savanna Ecosystems
  Plant and herbivore species in semiarid landscapes are subjected to many periods of water scarcity. This study was conducted to evaluate the effect of water as a limiting factor on savanna ecosystem components including functional groups of woody and herbaceous plants as well as herbivores. Numerical simulation of the savanna system in the Kruger National Park (South Africa) used the spatially explicit SAVANNA ecosystem model and 20 years of monitoring data collected by South African National Parks Board officials. Water availability in the SAVANNA model determines plant growth and death as well as herbivore distribution. Net Primary Production (NPP) of vegetation is determined as the product of water use through transpiration and water use efficiency. Herbivores will distribute according to available water. If water discharge does not support herbivore density dispersal will occur and mortality may follow if the demand continues to be unmet. Simulated herbaceous biomass and woody population levels were compared to field data to establish confidence in the model as a predictive tool. Additional analysis using Global Sensitivity Analysis methods highlighted the sensitivity of specific water balance components and their potential higher order interactions with other ecosystem components. Longer term management scenarios were simulated with 30 year climate files to explore ecosystem sensitivity to human interventions. In SAVANNA water stress is a significant contributor of plant and herbivore mortality. The frequencies of drought cycles play an important role and incite varying responses in the different herbivore and vegetation species. The cycles of drought have varying implications for the vegetative and herbivore species in the region; affecting carrying capacity of herbivores as well as potential degradation of land.