ASSESSING THE SPATIOTEMPORAL DYNAMICS OF CROP YIELDS AND EXPLORING THE FACTORS AFFECTING YIELD SYNCHRONY

Abstract

Variation in crop yields has significant impacts on food supply in many developing nations and on global food prices. I applied a recently quantified link between spatial and temporal variation to gain general insights on the dynamics of food production, as well as to test whether a prediction that relies on space-for-time substitution applies for crop yields, and at which spatial scale. I analyzed patterns of variation on global yield for 77 crops recorded in 212 countries over 22 years (1990 – 2012). I found that if we know how crop yields vary in space, we could predict variation in crop yields over time at various scales. Specifically, spatial variation can substitute for temporal variation in predicting the variability of yield of certain staple crops when synchrony and persistence (persistence = consistent differences in mean yield values among locations or regions) are taken into account. This space-time substitutability has potential to forecast temporal stability of food production from its spatial data alone, which should allow countries and various agencies to improve agricultural policies and production forecasts to ensure stability in local and global food supply. I also found that a crop’s preferred climatic conditions were strong predictors of synchrony between countries at the continental scale. This provided insights on the type of crops that are good candidates for effective use of spatial variability to predict their regional temporal variability in yields. These include crops that have high preferred-germination-soil temperature, low minimum crop water needs, and low minimum growing period. Lastly, as global warming increases crop yield synchrony, the total variability of global food supply increases, which results in lower stability in global food supply and exacerbates food insecurity. Combined with the predicted higher frequencies of climate extremes, the findings in this study reinforce the current view that climate change will have negative consequences on the global food supply.