BIODIVERSITY AND THE CORNUCOPIA OF FOODS

BIODIVERSITY AND THE CORNUCOPIA OF FOODS. Whenever you take up a bowl of paella, or a salad plate of mixed greens, nuts, and fruits, you are enjoying the benefits of biodiversity. There is something intrinsically pleasurable about a heterogeneity of vegetable varieties, shellfish species, or the ecological mosaic of marine and terrestrial landscapes sampled to prepare such dishes. Biodiversity can be simply defined as the "variety of life on Earth," and it includes both the richness of habitats found within different regions as well as the richness of species, varieties, and genes.

In a world where agricultural and aquacultural practices correspond to the growth rates and population densities of edible plants and animals, biodiversity can be sustained, without depleting harvests or degrading ecological habitats. But where traditional practices of food production and harvesting have been displaced, or species-rich landscapes have been degraded or converted to urban or industrial uses, this diversity is imperiled. In other words, the continued availability of this cornucopia of foods can no longer be taken for granted, and the term "biodiversity" is increasingly used in the context of loss of biodiversity or the extinction crisis. The number of species doomed to extinction each year of this coming century is projected by Harvard professor E. O. Wilson to be on the order of 27,000 unique and irreplaceable life forms. This extinction rate is the highest rate since humankind began manipulating life on earth.

Although the term "biodiversity" first came into vogue around 1988, during a conference on this theme sponsored by the National Academy of Sciences of the United States, synonyms such as "biological diversity" and "biotic diversity" had already been in currency among scientists and conservationists for some four decades. However, most people erroneously equated the term with species diversity or species richness, as if the number of plant and animal species in a given area served as the only indicator of biodiversity. "Biodiversity" is now considered to include the variety of life considered at all levels, from genetic variants belonging to the same species, through arrays of species and lifeforms, to the variety of habitats and ecosystems found within an ecological landscape including both wildlands and farmlands.

Let us first consider how our cornucopia of foods is filled with the genetic variation found within a single species. Consider, for example, the astonishing variety of vegetables and fruits grown and stored on just one patch of land, such as that of the Heritage Farm of the Seed Savers Exchange in Decorah, Iowa. The dozen or so members of the Seed Savers Exchange staff grow and maintain the genetic diversity represented by some 4,100 named varieties of tomatoes (one species), 3,600 varieties of beans (six species), 1,000 varieties of peas (one species), 1,200 chili peppers (four species), 1,200 squash and pumpkin varieties (four species), 400 melons (two species), 650 varieties of maize (two species), and 200 varieties of garlic (one species). Each of these varieties, whether it is a land race developed exclusively by traditional farmers and gardeners, or a cultivar developed by scientifically trained plant breeders, has been selected for its unique flavor, texture, color, size, shape, keeping time, as well as for its maturation rates, productivity, and resistance to pests, diseases, droughts, and freezes.

Unfortunately, many varieties such as these have already been lost from future use by gardeners, chefs, brewers, and the public at large. For example, it is estimated that 60 percent of the crop land races grown by indigenous tribes in North America at the time of first European colonization have been lost over the following five centuries. Several threats have led to losses of genetic replacement by modern commercial cultivars, and genetic contamination through accidental hybridization with modern cultivars, including genetically modified organisms (GMOs). Further consequences include genetic erosion due to the decline in traditional farming, along with reductions in planting areas and crop population sizes, and genetic extirpation resulting from the genocide or displacement of traditional farming communities, and termination of their agricultural practices.

In addition to genetic variation below the species level, biodiversity is influenced by the number of crop species grown in a given area and how they are inter-cropped. For example, some fifty botanical species of fruits, vegetables, and nuts can be found in some indigenous dooryard gardens, intermixed in what agroecologists term "polycultures." These crop mixtures often outyield the harvests that a single crop would produce on the same area of land, and harbor a variety of beneficial insects, such as predators on pests and pollinators.

At the landscape level, an ecological mosaic of fields, gardens, orchards, hedgerows, and managed wildlands provides what is now termed "agrobiodiversity," which includes habitat for both wild and domesticated organisms. It is at this level that land conservation organizations interested in protecting the diversity of foods desired by the public must succeed, for this diversity can be easily lost without the cultural landscapes that sustain species, their interactions with one another, and traditional ecological knowledge about how to manage them.

Gary Paul Nabhan