Abstract
Agroforestry is a promising adaptation measure for climate change, especially for low external inputs smallholder maize farming systems. However, due to its long-term nature and heterogeneity across farms and landscapes, it is difficult to quantitatively evaluate its contribution in building the resilience of farming systems to climate change over large areas. In this study, we developed an approach to simulate and emulate the shading, micro-climate regulation and biomass effects of multi-purpose trees agroforestry system on maize yields using APSIM, taking Ethiopia as a case study. Applying the model to simulate climate change impacts showed that at national level, maize yield will increase by 7.5 and 3.1 % by 2050 under RCP2.6 and RCP8.5, respectively. This projected increase in national-level maize yield is driven by maize yield increases in six administrative zones whereas yield losses are expected in other five zones (mean of −6.8% for RCP2.6 and −11.7% for RCP8.5), with yields in the other four zones remaining stable overtime. Applying the emulated agroforestry leads to increase in maize yield under current and future climatic conditions compared to maize monocultures, particularly in regions for which yield losses under climate change are expected. A 10% agroforestry shade will reduce maize yield losses by 6.9% (RCP2.6) and 4.2 % (RCP8.5) while 20% shade will reduce maize yield losses by 11.5% (RCP2.6) and 11% (RCP8.5) for projected loss zones. Overall, our results show quantitatively that agroforestry buffers yield losses for areas projected to have yield losses under climate change in Ethiopia, and therefore should be part of building climate-resilient agricultural systems.
Highlights
Climate change will have severe impacts on food production in many tropical areas as conditions become marginal or highly variable (Hoegh-Guldberg et al, 2018)
The findings at country level that maize yield will increase under climate change corroborate with previous studies (Thornton et al, 2009; Araya et al, 2015; Muluneh et al, 2015; Alemayehu and Bewket, 2016; Thomas et al, 2019). We showed these positive climate change effects on maize yields are explained by strong increases in rainfall in parts of the country, which will increase the agronomic conditions for maize cultivation compared to current levels, especially in the highlands
Our results indicate that 10% shading agroforestry system will increase yield in North Wollo by 39% under current climatic conditions but reduce it under climate change by 30% under RCP8.5 while for North Shewa it will decrease yields by 23% under current conditions and increase maize yield potential under both scenarios. While these regional disparities are directly explained by differences in altitude and resultant radiation levels, we demonstrate that multi-purpose trees agroforestry contribution under climate change may not be positive for all areas in Ethiopia at the modeling density
Summary
Climate change will have severe impacts on food production in many tropical areas as conditions become marginal or highly variable (Hoegh-Guldberg et al, 2018). As such, building a resilient agricultural system in the tropics is needed to cope up with the impacts of the changing climate yet remaining within planetary boundaries. The capacity of a system to recover from climate-related shocks like droughts, heavy precipitation, or floods will be crucial with ongoing climate and global change. Such resilience of agricultural systems should be established, among others, Agroforestry for Maize Yield Buffering through climate adaptation measures. Agroforestry is one of few measures that fit into the foregoing description and criteria
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