Changes in the differences in crop diversity among 22 FAO-defined agricultural regions from 1961–2014.

Panel A presents a visualization of regional differences in crop β-diversity (calculated following a common metric in community ecology: non-metric multidimensional scaling (NMDS)). The values associated with this technique (NMDS axis 1 and NMDS axis 2) are plot and interpreted here visually as a “map of similarity”: points closer to one another are region-by-year combinations with more similar crop composition, while points further from one another are more dissimilar in crop composition. For clarity only data points from 1961, 1980, 2000, and 2014 are shown; corresponding confidence ellipses represent 1 standard deviation for each of these four years. Sizes of symbols within a region corresponding to year with 1961 represented by the smallest symbols, 1980 medium size symbols, 2000 large symbols, and 2014 the largest symbols. Panel B represents changes in regional crop similarity from 1961 to 2014. Data points represent similarity between any two regions, and trend line represents a segmented linear regression model fit to the entire dataset fit. Shaded gray bands are 95% confidence limits surrounding the model.