Crop diversity in the world’s conventional agricultural production systems has changed drastically over the past 50 years following the Green Revolution, as a result of multiple socio-economic, political, and environmental forces. The integration of the vast majority of large-scale production agricultural into a global food distribution system, has contributed to major shifts in dietary preferences, changes in farm- and landscape management practises, and the cultivation of new crops. On one hand, these and other factors have led to a wider diversity of plant species being incorporated into the world’s agricultural plant production systems. But at the same time, evidence suggests that a small number of crops from certain families, namely cereals (Poaceae) and pulses (Fabaceae), are becoming more dominant in some regions. Taken together, there remain uncertainties surrounding how crop diversity has changed through time, and how these patterns may differ across continents or regions. We used data from the Food and Agricultural Organization of the United Nations to evaluate shifts in the crop species-, functional, and phylogenetic diversity from 1970-2014 across global, regional, and sub-regional scales.
Results/Conclusions
At global and continental scales, the species-, functional-, and phylogenetic diversity of crops has increased strongly and significantly over the past half-century. Crop diversity in agroecosystems of Europe and North and South America show the earliest peaks in the mid-1990s, while agricultural systems in Asia, Africa, and Oceania continued to diversify through the early-to-mid 2000s. At global or continental scales, metric of species-, functional-, and phylogenetic evenness among crops have nearly doubled in the past 50 years. Patterns of change in diversity differed widely among sub-regions within continents, with indications that socio-economic characteristics, including the classification of countries as net food importers, significantly explain the rate of change in crop diversity through time. In finding sharp increases in taxonomic-, phylogenetic, and functional evenness of crops over the past 50 years, our results indicate that at global or continental scales, large-scale agricultural systems have shifted towards taxonomically-, evolutionarily-, and functionally homogeneous plant assemblages.