Changes in global cropland area and cereal production: An inter-country comparison

Although cereal production is a linear function of cropland area in principle, the relationship between area change and production change is nonlinear at a larger geographical scale due to the spatially heterogeneous use of land. Based on globally gridded land cover maps between 2000 and 2010, this study presents a country-level comparison to understand how cropland area change contributes to cereal production variation across the world's major cereal producers. First, a map of potential cereal productivity is applied to represent the spatially varied biophysical capacity, and the cropland area change in primary and marginal locations are calculated separately for individual countries by adopting the country's average cereal productivity as a reference. Then the area-change-induced potential cereal production change is estimated and correlated with the actual production change at the country level. The results show that most countries increased cropland area in primary locations. A few countries decreased cropland area, and the area losses are mainly occurred in primary locations as well. Moreover, China and USA achieved a marked increase in actual production with an expected decrease in potential production. In contrast, Brazil, Argentina and Nigeria have a higher increase in potential production against a relatively lower increase in actual production. Combining these, a cluster analysis indicates that some countries better exploited cropland productivity (as represented by China), and some countries better allocated cropland area (as represented by Brazil). Although the former group has reduced hunger more significantly, sustainable cereal production requires balanced development in terms of both productivity-improvement and area-optimization, which simultaneously ensure production and minimize environmental effects. Consequently, the current comparative analysis provides a preliminary guideline for developing national-level strategies by comparing the performance of one country to that of others.