Biodiversity and Agriculture

Tomato Horn WormBiodiversity insures against threats to crops from pests, diseases and climate change.

The yearly addition of some 77 million people poses many extremely difficult challenges for human beings, especially in producing adequate supplies of food and clean water without irreversibly damaging our environment.

Protecting biodiversity in the ecosystems that support food production and fresh water, and preserving genetic diversity in our crops, are both critical to ensuring our ability to produce food with ever-shrinking terrestrial and aquatic resources.

Of the myriad species of plants and animals available for human consumption, modern agriculture uses only a few. According to the UN's Food and Agriculture Organization, only 12 plant species provide 75% of our total food supply, and only 15 mammal and bird species make up over 90% of livestock production.

Monocultures, the agricultural practice of producing or growing genetically similar, or essentially identical plants, over a large areas (stands), year after year, is widely used in modern industrial agriculture. It is often argued that monoculture produces greater yields by utilizing plants' abilities to maximize growth under less pressure from other species and more uniform plant structure.

However, these plants are selected because of their ability to grow well under the specific conditions of a particular place, and therefore are at greater risk when these conditions change, for instance in extreme weather, than are genetically diverse stands. Genetically diverse crops can better survive in environments in which conditions fluctuate, because some are vulnerable to certain changes and other are not. Thus genetic diversity is likely to reduce the odds of massive crop failure and to contribute to greater stability of production. 

The vulnerability of monocultures to disease and insects also illustrates this point. Pathogens spread more readily, and epidemics tend to be more severe, when the host plants (or animals) are more genetically uniform and crowded. The pathogens encounter less resistance to spreading than they do in mixed stands. Outbreaks of disease, invasions of insects, and climatic anomalies have caused many wholesale crop and animal failures in the past.

What is also not appreciated is that modern crops and livestock vitally depend on hundreds of thousands of other species, including insects and birds that pollinate crops and feed on pests, and numerous microbial species that live on and in plants and animals, and that are especially critical to survival.

Photo by Robert Ireton |