- The Borlaug 100 conference programme now has links to many of the presentations.
- Including a link to Rachel Laudan’s history of Wheat: the grain at the center of civilization.
- Oh boy. A new edition of FAO’s Plant Breeding & Genetics Newdsletter.
- Video on “Reviving Nepal with hybrid tomatoes“. So many questions, so few answers.
The Borlaug 100 meeting.
Gordon Conway (slide 29) calls for an emphasis on `greater biodiversity’ to achieve `sustainable ecological intensification’. While this recommendation for biodiversity could apply to some (rare) agroecosystems it ignores two ecological principles that mandate lesser rather than greater biodiversity for much crop production.
One principle is disturbance: in particular its impact on competition: on-going inter-species competition generally reduces the populations of each of the possibly many species competing for limiting resources. Farmers originally chose crops by the ability of ancestral species to escape competition – and therefore build up their populations and biomass – by ecological specialization. A first specialization comes from the adaptive value of food storage in plant competition. Major food crops – and their wild relatives before them – store food in seeds and tubers, often lots of it (which is why they were originally chosen as crops). In seasonal climates this food storage is a mechanism for better competition at the start of the growing season with plant species that store less food. But food storage alone is not enough to compete with the woody perennials that will dominate climatic climax vegetation by their bulk. Something else is needed: this something is the ability to grow in the more extreme ecological conditions where trees cannot grow. Hence most of our food comes from the very limited biodiversity of the few highly adapted species able to grow in conditions that prevent permanent woody vegetation. Arable farming, with its tilling and weeding, mimics the natural severe disturbance of flood, fire, and landslips or whatever else disturbance specialization. The lower biodiversity of highly adapted `extremophytes’ (our crops) is better for food production.
The second principle relates to the interaction of species in food chains. As autotrophs our crops are the food of heterotrophs – including the biodiversity of co-evolved plant pests and disease that limit production: the greater the biodiversity of host-specific pests and disease the lower the plant production. There is a simple, world-wide, mechanism to reduce the biodiversity of co-evolved pests and diseases: introduce crops to another continent. This mechanism has been known for more than a century, not least by colonial botanists experimenting with plantation agriculture (with a few disasters like coffee in Ceylon). At least 70% of countries have more than 50% of their crop production from species introduced from other continents. The lower biodiversity of co-evolved pests and diseases following crop introduction is better for food production.
As both these mechanisms are profoundly `ecological’ Conway is wrong to call for `greater biodiversity’, or, as a minimum, not generically right. He is certainly ignoring (or not understanding) two present miracles of crop production: introduced soybean in South America and introduced oil palm in Indonesia, both, by my reckoning, good examples of `sustainable ecological intensification’.