Potential, attainable, and current levels of global crop diversity

Abstract

High levels of crop species diversity are considered beneficial. However, increasing diversity might be difficult because of environmental constraints and the reliance on a few major crops for most food supply. Here we introduce a theoretical framework of hierarchical levels of crop diversity, in which the environmental requirements of crops limit potential diversity, and the demand for agricultural products further constrain attainable crop diversity. We estimated global potential, attainable, and current crop diversity for grid cells of 86 km2. To do so, we first estimated cropland suitability values for each of 171 crops, with spatial distribution models to get estimations of relative suitability and with a crop model to estimate absolute suitability. We then used a crop allocation algorithm to distribute the required crop area to suitable cropland. We show that the attainable crop diversity is lower in temperate and continental areas than in tropical and coastal regions. The diversity gap (the difference between attainable and current crop diversity) is particularly large in most of the Americas and relatively small in parts of Europe and East Asia. By filling these diversity gaps, crop diversity could double on 84% of the world’s agricultural land without changing the aggregate amount of global food produced. It follows that while there are important regional differences in attainable diversity, specialization of farms and regions is the main reason for low levels of local crop diversity across the globe, rather than our high reliance on a few crops.

Both long-term grasslands and crop diversity are needed to limit pest and weed infestations in agricultural landscapes

“…However, four limitations of our study warrant further analyses. First, the range of variation of crop diversity, which ranged from three to seven crops (in the 1 km buffer, which is consistent with the range of variation found in European farms) in the present study might have limited our ability to detect crop diversity effects that may emerge at higher levels of crop diversification as observed in southern European countries ( 46 ). Second, crop diversity was calculated considering crop taxonomy while a better characterization of crop diversity based on phylogenetic distances or crop traits (e.g., sowing date, plant height, or nitrogen amount: see ref.…”

Indigenous crop diversity maintained despite the introduction of major global crops in an African centre of agrobiodiversity

“…Finally, we note that as a globally important centre of crop diversity and domestication with a regionally unique climate, Ethiopia may not be widely representative of trends in other countries or regions. Indeed, the stability of indigenous agroecosystems in our study may be partly due to the comparatively minimal extent of colonial era agri‐polices, partly shielding Ethiopia from the effects of mid‐20th century green‐revolution influenced interventions (Till, 2021) and subsequent commercial crop specialisation (Merlos & Hijmans, 2022).…”

Landscape Biodiversity in Terms of Crop Structures: A Spatial Assessment for Poland

“…The study was based on data from the General Agricultural Census 2020 in Statistics Poland's (CSO) Local Data regarding the area of individual crops as of June 31, 2020. After verification of the available data, the following crops and crop groups were included for further analysis: winter wheat (including spelt) (1), spring wheat (including spelt) (2), winter rye (3), spring rye (4), winter barley (5), spring barley (6), oats (7), winter triticale (8), spring triticale (9), winter cereal mixtures (10), spring cereal mixtures (11), maize for grain (12), industrial (annuals) (13), total edible legumes for dry grain (14), potatoes (15), sugar beets (16), oilseed rape and agrimony, combined (17), field vegetables (18), spring catch crops (19), winter catch crops (20). In addition to data on individual species (e.g., wheat, rye, etc.…”

“…Figure 4. Sample fragment of CORINE Land Cover maps (same scale)By closing the gap between current and potential diversity, crop diversity could double on 84% of the world's agricultural land without changing the total amount of food produced globally(Merlos & Hijmans, 2022), and this would improve the quality and value of ecosystem services provided(Sujetovienė & Dabašinskas, 2023). The Common Agricultural Policy and the European Green Deal strategy play an important role in this respect, improving the biodiversity of the agricultural landscape through various financial incentives(Vistarte et al, 2023).…”