The paper “Forgotten food crops in sub-Saharan Africa for healthy diets in a changing climate” by Maarten van Zonneveld, Roeland Kindt, Stepha McMullin, Enoch G. Achigan-Dako, Sognigbé N’Danikou, Wei-hsun Hsieh, Yann-rong Lin, and Ian K. Dawson has won the PNAS 2023 Cozzarelli Prize for the best paper of the year in Applied Biological, Agricultural, and Environmental Sciences. Here’s the abstract:
As the climate changes, major staple crop production in sub-Saharan Africa becomes increasingly vulnerable. Underutilized traditional food plants offer opportunities for diversifying cropping systems. In this study, the authors used climate niche modeling to assess the potential of 138 traditional food plants to diversify or replace staple crop production in sub-Saharan Africa by 2070. The authors report that staple crops may no longer be able to grow at approximately 10% of locations by 2070. Further, the authors identified 58 traditional crops that provide complementary micronutrient contents suitable for integration into staple cropping systems under current and projected climatic conditions. The results suggest that diversifying sub-Saharan African food production with underutilized crops could improve climate resilience and dietary health.
And here’s a video explaining the results:
This `Forgotten crops of Africa’ has got hold of the wrong end of the stick (in fact, several sticks). There is no reason why crop diversification provides resilience in the face of climate change. In regions of climatic and other abiotic stresses natural vegetation moves to monodominance of a single highly adapted species. It is the selective stress and the adaptation to it that is important, not species diversity. A major example is Asian rice, that can handle flooding and drying that kills other species. A natural analogue of the crop is the vast monodominant beds of wild rice at the mouth of the Indus river. There are also stressed (probably by fire) vegetational wild analogues of wheat, barley, oats, rye and sorghum, all monodominant (and all adapted by their annual habit to avoiding seasonal fires).
In addition, why use African underexploited species? The easiest way to diversity cropping is by plant introduction (the `Columbian Exchange’ for starters), as effectively used in the USDA Plant Introduction system. Collect good varieties (not diversity), send seed samples all over the country for farmer assessment, pick top crops pre-adapted to all kinds of cropping. All backed up with a tight plant quarantine to prevent pest and disease constraints following the introduced species. The obvious value of crop introduction for diversification also depended on a large network of botanic gardens – not least Kew.
As an example the paper notes, for Kenya, distribution of `forgotten crops’ includes food trees such as Anacardium occidentale (cashew) and Tamarindus indica (tamarind). Cashew is introduced (not African) and both crops are certainly not forgotten. I remember working on the Kenya coast and often buying a kilo of cashew from the large processing factory south of Malindi. This paper sounds like ICRAF trying to generate work for itself by promoting tree crops. And anyone telling the Indian inhabitants of East Africa that tamarind is `forgotten’ will get their head bitten off.
The best way to adapt to climate change is not diversification but extensive regional trials to pick out winners, that is, the most adapted samples. These trials have already been done very extensively—over 50 years by the CGIAR—millions of data points in need of analysis to counter climate change. And we need ever-present plant quarantine to protect introduced crops—already a feature of `Plant Introduction’ powerhouses such as the USA and Australia.
As a coincidence (??) the `forgotten crops of Africa’ paper was published at the same time the U.S. Department of State launched a “Vision for Adapted Crops and Soils” (VACS) to adapt African “forgotten crops” to anticipated effects of climate change. Also the hope was that scaling-up production and access to more diverse, climate-resilient crop varieties will support good nutrition and better livelihoods and provide a source of local resilience in the face of climate change.
There is the belief that forgotten crops are well-adapted to local conditions. This is fact-free `pie in the sky’ thinking. Indigenous crops are often severely constrained by their coevolved pests and diseases. That is why `introduced crops do better’ (at least for a time): they have no coevolved pests and diseases to counter. The staple food crops of Africa (maize, rice and cassava) all benefitted from their introduction and all three are decried in the two documents (`forgotten crops of Africa’ and also VACS).
The choice for Africa is stark. You either grow introduced staple crops yourself (as now) or you import staple foods from North America and Australia. And if you want nutrition from your food, get it from minor fruit and vegetable crops from local markets or your own shamba. We need a new maxim: “Beware of people from crop-exporting countries giving you bad advice on what to grow”.