In the semi-arid and arid ecosystems of eastern Africa, high climatic variability drives heterogeneity in the availability of ecosystem services. Pastoral societies in this region practice livelihood strategies that are attuned to exploiting these patchy services. Accessing resources over large areas through seasonal migrations is a vital mechanism underpinning these strategies. Ongoing land use change in the region, that constrains pastoral mobility, is leading to reduced pastoral resilience to droughts. Understanding how land use change modulates the ability of pastoral communities in eastern Africa to access critical ecosystem services is key to devising national level policies, particularly those aimed at alleviating hunger and poverty. We are developing SPIRALL, a region-scale agent-based model that simulates pastoralist household decisions. In SPIRALL, we explore pastoralist responses to the availability of ecosystem services through rules governing pastoralist movement and livestock trading decisions. To capture the coupled reality of socio-ecological systems in the region we are linking SPIRALL to L-Range, a model that simulates rangeland ecosystem function. SPIRALL and L-Range are linked via a livestock herd dynamics model. Monthly biomass availability simulated by L-Range influence livestock population growth parameters, whereas foraging by livestock alters ecosystem function through a depletion of aboveground biomass.
Results/Conclusions
Using the coupled model, on a monthly timestep, we simulate household responses to climate driven changes in the availability of ecosystem services over a twenty-year period (2000 – 2020). At each timestep, our coupled model produces estimates of the proportion of households that fail to meet their nutritional requirements and economic needs, through movement or livestock trading. We validate these estimates against existing data on food insecurity in the region over the same period. In addition, we aim to explore how pastoralist households respond in scenarios where pastoral mobility and access to key resources is constrained in a manner that resembles possible future patterns of fragmentation and land use change. We place these results in the context of policy decisions that eastern African nations are contending with as they work towards achieving their Sustainable Development Goals.