Sustainability science studies the drivers of change that alter natural and human systems now and into the future, with components that may be resilient or non-resilient. Our focus is on rangelands of East Africa, where drivers of change include rapid population growth, poverty, degraded rangelands, declining wildlife, land fragmentation, reduced mobility, and more frequent drought associated with climate change. Coupled systems computational applications often include one or more models simulating ecosystem responses, joined to an agent-based model representing individuals or households. We applied a coupled systems approach to Samburu, Kenya, where residents raise cattle, goats, and sheep, and land may be rented to those outside the system to raise wheat. The Savanna ecosystem model simulated forage production and wildlife populations, and the DECUMA agent-based household model was used to simulate decision making by residents as they respond to changes in services. Two applications were created, one for the lowland area of Mbaringon, and the second for high elevation Siambu. Two scenarios simulated represented the areas as drought refugia for pastoralists outside the region, where we increased livestock on the area during drought, and payments required to households to offset putting some of the lands within Mbaringon to wildlife tourism.
Results/Conclusions
We quantified effects of immigration of herds during drought and changing wildlife populations on local household well-being. Immigration of outside animals caused a 0.5 decline in animals per person (i.e., tropical livestock units per adult equivalent) and an increase in supplemental foods needed. In surveys, we found that animals per person low (1.88 TLUs AE-1 for Mbaringon, and 2.0 TLUs AE-1 for Siambu), and so a 0.5 decline is significant. Energy from milk declined markedly from the moderate drought. Increasing wildlife caused declines in livestock and household incomes up to 6000 Kenyan shillings, as expected, but payments of the magnitude that may be expected did not offset losses. The coupled systems approach allows more direct inference of changes and for changes in the ecosystem and human components to influence each other. Challenges include the complexity of the endeavor and the issues addressed, difficulties in model validation, the rates of change, and the political wills that may override what scientists view as sustainable solutions. Modeling will improve as psychological research refines decision making rules, the temporal and spatial grain of simulations increases, and the ability to model many thousands of agents expands.