Indigenous climate adaptation sovereignty in a Zimbabwean agro-pastoral system: exploring definitions of sustainability success using a participatory agent-based model

Indigenous peoples are experiencing a wide range of negative impacts due to climate change and should have the right to determine for themselves how to adapt to these changes and define successful adaptation. These adaptations can then be culturally appropriate and grounded in Indigenous knowledge systems; however, the accelerating rate of change in social-ecological systems can be a challenge for traditional knowledge. Appropriate participatory modeling tools such as agent-based models (ABMs) may be of assistance to Indigenous groups in thinking through how systems may change in the future. Using the Zimbabwe Agro-Pastoral Management Model (a community-based ABM cocreated with farmer-researchers in Mazvihwa Communal Area), we explored how different definitions of sustainability affected the conclusions from the model, including average annual harvest and the persistence of resources (livestock, harvest, and woodland biomass) in the modeled system above minimum thresholds. For very low persistence thresholds, these two measures of success traded off against each other (with higher cropland proportions favoring harvest success and lower cropland proportions favoring persistence success); and different combinations of management interventions favored one or the other definition of sustainability. New insights came from community suggestions of higher persistence thresholds for livestock, crops, and woodland, whereby the model suggested that an intermediate proportion of cropland could be most successful. In all cases, higher year-to-year rainfall variation reduced sustainability success, regardless of the definition or thresholds used. Cocreating, cotesting, and coadaptation of the model and the use of multiple definitions rendered the findings more relevant for local application. The community in Mazvihwa has many ways to adapt to challenging circumstances, and local nongovernmental organization The Muonde Trust has used the model to work with local leaders to support collective action on land use planning to protect woodland from deforestation.