Global relationships between crop diversity and nutritional stability

Nutritional stability - a food system's capacity to provide sufficient nutrients despite disturbance - is an important, yet challenging to measure outcome of diversified agriculture. Using 55 years of data across 184 countries, we assemble 22,000 bipartite crop-nutrient networks to quantify nutritional stability by simulating crop and nutrient loss in a country, and assess its relationship to crop diversity across regions, over time and between imports versus in country production. We find a positive, saturating relationship between crop diversity and nutritional stability across countries, but also show that over time nutritional stability remained stagnant or decreased in all regions except Asia. These results are attributable to diminishing returns on crop diversity, with recent gains in crop diversity among crops with fewer nutrients, or with nutrients already in a country's food system. Finally, imports are positively associated with crop diversity and nutritional stability, indicating that many countries' nutritional stability is market exposed. Crop diversification could be important for food security. Here, using methods from network science, the authors find that a positive relationship between crop diversity and nutritional stability globally does not necessarily equate to improving nutritional stability in a given country.

Automated summary

There is a positive, saturating relationship between crop diversity and nutritional stability across countries, but over time nutritional stability remained stagnant or decreased in all regions except Asia. Crop diversification is important for food security, however recent gains in crop diversity among crops with fewer nutrients may not necessarily improve nutritional stability in a given country.