How does agricultural biodiversity contribute to food security?

Summary

The contribution of agricultural biodiversity to agricultural production and food security is widely accepted. In the economic research this contribution has been evaluated from the production and from the consumption side. On the production side, agricultural diversity provides services that support the productivity of the system.
These services include pest control, soil fertility, or in general system resilience to extreme climate events. On the consumption side, agricultural biodiversity enhances the diet diversity thereby enabling small farmers to consume a variety of foods.
To our knowledge, however, the long term economics contribution of agricultural biodiversity to agricultural production and food security has not been evaluated in depth. On the production side some economic research has been done on quantifying the effect of crop diversity on output, output variability and probability of crop failure (Birol et al. 2006; Birol et al. 2009; Di Falco and Chavas, 2006, Di Falco, et al., 2006, Edmeades et al. 2006; Kwikiriza et al 2010; Smale, et al., 1998, Smale et al., 2003, Smale 2006; Van Dusen and Taylor 2006). These studies using different methodological approaches have shown some lights on the interaction of biodiversity and its contribution to food security.
To evaluate a system requires a system approach
The results however also shed light on the conditions need for agricultural biodiversity to contribute to food security and poverty alleviation. Most of these studies use a narrow definition of agricultural biodiversity referring mainly to crop diversity and in several cases to intra-specific diversity. The main reason behind is simplicity. To evaluate a system requires a system approach and there are on one hand limited tools and methods that can be used to evaluate the system. On the other hand modeling an agroecosystem over time and at the same time translating ecological processes into economic terms it is a rather complicated exercise. The global consequences of climate instability and economic crisis however are making more and more evident the need to invest in long term approaches and data collection.
High correlation between dietary diversity and nutrition adequacy
On the consumption a growing body of research shows that there is a high correlation between dietary diversity and nutrition adequacy (Mouille and Ruel, 2003, Ekesa et. al 2008, Johns and Eyzaguirre 2007; Frison 2006). Not only number of species available is important, the greater the intra-species plant genetic diversity, the greater the variety of nutrients available to the population, hence better health outcomes (Kennedy et al. 2010).
This relationship has been found especially significant in developing countries. Emphasizing dietary diversity in the context of poverty alleviation stems from the concerns of nutritional deficiency among the poor in developing countries and the importance of increasing food group variety to ensure adequate nutrient intakes.
The pathway of poverty impact will not be complete unless we consider the effect of crop species diversity on dietary diversity and nutrition, because persistent malnutrition of the population could potentially contribute to persistent poverty. As in the case of production, this research effort requires long term investment and the implementation of sound methodological approaches.
There is therefore an evident need for more understanding of the role of agricultural diversity towards ecosystem productivity (food production as an ecosystem service) and thus to poverty alleviation. Taking an objective view at agricultural diversity and its effects on yield, yield stability and dietary diversity can help identifying where, what and how agricultural biodiversity can contribute to poverty alleviation.