It is remarkable to me that it has taken so long to effectively harness the concept of diversity and the process of diversification as forces for transformation of the dominant industrial model of simplified, monoculture agriculture. For quite some time we have known the importance of diversity in natural ecosystems. This importance was pointed out by two giants in natural ecosystem ecology, both who recently left us. The passing of Thomas Lovejoy and E. O. Wilson gives us reason to reflect on the future of our planet, and hence the future of ourselves. Both of these people contributed greatly to our understanding of the nature of life. But most importantly, they made major contributions to our understanding of why ecological diversity is important. They saw bigger things!
Tom Lovejoy is widely recognized as the conservation biologist credited with popularizing the term biodiversity, probably referring to it first as biological diversity before it was shortened to its more familiar version. He was also a passionate defender of the Amazon Rain Forest, establishing a pioneering project almost 40 years ago known as the Biological Dynamics of Forest Fragments Project. The B.D.F.F.P. was a collaboration between ranchers and scientists to set up different sized patches of rain forest in order to study the impacts of forest clearing on species diversity over time. Small fragments too often lost species.
E.O. Wilson is known by many as a modern day Darwin, and is perhaps best known as an evolutionary ecologist despite the controversy generated by his views about the field of sociobiology. His early work on the biogeography of Islands and his lifelong work on the incredible diversity of ants were united through his active involvement in the global conservation of biodiversity. His concern for the scale of extinction and biodiversity loss was expressed through his advocacy of forest protection, reaching the point in his later life where he called for setting aside 50% of the earth’s surface free of humans for other species to survive, concurrently ensuring our own survival.
Diversity has a variety of dimensions. It starts with the number of species in a system, but it soon expands to include genetic, spatial, structural, functional, and temporal dimensions. All of them integrate in time and space, not to mention evolutionarily, to create and maintain the diverse assemblages of ecosystems occupying our planet. These dimensions interact, with complex relationships, dependencies, feedback loops, and ecological processes providing a foundation for ecosystem structure and function that leads to stability and resilience through time.
For agroecologists, bringing ecological diversity into food and farming systems is key to the transformative change needed to achieve food system sustainability. Many indigenous, traditional, and local smallholder farming systems have been doing this for a long time, and provide important models of how to farm through diversification. Diversity is of value in agroecosystems through a variety of reasons. With higher diversity in multiple crop systems, there is greater microhabitat differentiation, allowing the component species to occupy their ideal habitat. As diversity increases, so do opportunities for coexistence and beneficial interactions between species. Open habitats in an agroecosystem can be occupied by many different useful species, rather than weedy species. Different species populations present in the system can allow overlapping predator/prey relationships to promote biological control. Better resource-efficiency can occur when multiple species with different needs occupy a cropping system with habitat diversity. Diversity – especially that of the belowground part of the system – performs a variety of ecosystem services that have impacts both on and off the farm, such as nutrient cycling, regulation of local hydrological processes, and sequestration of carbon.
Diversity in the agricultural landscape can also contribute to the conservation of biodiversity in surrounding natural ecosystems, something Lovejoy and Wilson would appreciate.
As we also know, ecological diversity is only part of the story. It reduces risk of crop loss due to climatic factors such as drought or frost, as well as unpredictability of markets, food chains, and other supply-side factors. Social, economic, and cultural diversity goes hand in hand with nature as diversification promotes and permits food sovereignty and social justice in food systems. Linking ecological diversity and social diversity can create strong forces for food system transformation.
Both naturalists saw many extreme cases of biodiversity loss during their lives, and even today deforestation of the Amazon is on the increase. Despite such loss, though, Lovejoy and Wilson remained determinedly hopeful. There was still time to save, they believed, if not the entire Amazon, then most of it; if not every species, then the great majority. Lovejoy liked to say that optimism was “the only option.” Building on their legacy, agroecologists must accelerate research on ways biodiversity plays important roles in agricultural sustainability, and advocate for the changes needed to make diversity a key component of food system change.