UBC Theses and Dissertations
Can forests increase food production? Exploring landscape configuration and crop productivity - a case study from Southern Ethiopia Yang, Kevin
Understanding the factors influencing agricultural yields and productivity is vital to food security. For millions of smallholder farmers, however, estimating field-level yields can be challenging. Furthermore, within agricultural landscapes interspersed with forests and trees, agricultural productivity in fields may be impacted by nearby forests, hedgerows, and other forms of tree cover. In an agricultural-forest mosaic in Southern Ethiopia, I used high spatial resolution (5-10m) satellite imagery to identify and differentiate two primary crops (with >90% accuracy) and assess the impact of nearby forest patches on wheat productivity. Second, using a suite of vegetation indices (VIs) as a proxy for wheat productivity, I determined whether productivity was enhanced or suppressed with increasing distance to forest. Results indicated that the proxies for wheat productivity increased by as much as 5% in parts of fields within 30 m of forest edges compared to fields further from forests. Lastly, I used historical and hypothetical future scenarios to examine the landscape-level implications of my results on overall wheat production. To do so, I applied the estimated 5% productivity increase to a series of agricultural-forested landscapes based on forest cover characteristics from the same study area. My goal was to compare and contrast landscapes to determine forest amounts and configurations which could optimize food production while minimizing forest loss. Between 1967 and 2013, a land cover and fragmentation analysis of Landsat and air photos showed a general trend towards reforestation (increase of ~8%) of more fragmented and sparser tree cover throughout the landscape over time. From hypothetical scenarios I found that forest edge productivity increases created non-linear food production benefits with hedgerow expansion. Differences in yield and production increases were ~2x higher when transitioning from a landscape with low to medium tree cover than transitioning from a landscape with high to higher tree cover. My results highlight potential benefits of a landscape approach for enhancing smallholder agricultural productivity in Southern Ethiopia. I argue that considering a landscape perspective can help support food security goals, particularly within the context of climate change considerations, and should play a more prominent role in planning for forest conservation and restoration.
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