Benefits of crop diversification for biodiversity and ecosystem services

Increasing the diversity of cultivated crops, species or cultivars is expected to help preserve biodiversity and enhance ecosystem services in agricultural landscapes. But individual local experiments evaluating crop diversification practices and even meta-analytical synthesis of experimental studies are scattered in their scope, quality and geographical focus. In an effort to make sense of this trove of information, we integrate the results of 5,662 experiments representing more than 48,600 paired observations over 80 experimental years, through the compilation of 83 meta-analyses covering more than 120 crops and 85 countries. The diversification strategies analyzed in the literature are diverse and are here regrouped into five broad categories (i.e., agroforestry, associated plants, intercropping, crop rotation and cultivar mixture). Our exhaustive literature synthesis shows that overall, crop diversification significantly enhances crop yields (median effect +13%), associated biodiversity (+24%), and several ecosystem services including water quality (+84%), pest and disease control (+63%), and soil quality (+11%). While these aggregated global results support the many benefits of adopting more diversified cropping systems, we also identified high variability between meta-analyses for most of the diversification practices examined. This strong global heterogeneity highlights the importance of contextual information about agricultural diversification for local decision-making. Our global database provides important insights into the contextual performance of crop diversification practices that can provide this needed guidance to agricultural and environmental decision-making.