Biological Meltdown: The Loss of Agricultural Biodiversity
By Hope Shand
Soon after peasant farmers first led plant explorers to wild stands of Zea diploperennis (perennial maize) in Mexico's Sierra de Manantlan in the late 1970s, plant breeders hailed the discovery as one of the botanical finds of the century. The rare perennial maize proved to be resistant to seven viral diseases that plague domesticated maize, and scientists predicted that Zea diploperennis could be worth as much as $4.4 billion to the commercial maize (corn) industry. Conservationists called for the establishment of a nature preserve to protect the rare maize in its natural habitat because they feared that poor farmers living nearby, in constant need of grazing land for their cattle, would soon wipe out the few remaining patches of wild maize by grazing cattle in the area. A nature preserve was eventually established, and peasant farmers no longer threatened the rare diploperennis. But within a few years, the forest began to invade the fields of wild maize. The plants were crowded out and began to disappear. Scientists soon realized that the local farmers had been intentionally conserving the wild maize by using a traditional practice of grazing their animals on dry fodder during the dormant season. Local farmers controlled the growth of the surrounding forest without harming the rare perennial maize plants. Retired vice-president for research at Pioneer Hi-Bred (the world's largest seed company), Donald Duvick, respectfully observes, "It seems that the farmers knew exactly what they were doing, and had more wisdom than the well-meaning environmental scientists."
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Why Are We Losing Agricultural Biodiversity?
The greatest factor contributing to the loss of crop and livestock genetic diversity is the spread of industrial agriculture and the displacement of more diverse, traditional agricultural systems. Beginning in the 1960s and 1970s, the Green Revolution introduced high-yielding varieties of rice and wheat to the developing world, replacing thousands of farmers' traditional crop varieties and their wild relatives on a massive scale. The same process continues today. New, uniform plant varieties are replacing farmer's traditional varieties - and the traditional ones are becoming extinct.
In the United States, more than 7000 apple varieties were grown in the last century. Today, over 85 percent of those varieties - more than 6000 - are extinct. Just two apple varieties account for more than 50% of the entire US crop. In the Philippines, where small farmers once cultivated thousands of traditional rice varieties, just two Green Revolution varieties occupied 98% of the entire rice growing area in the mid-1980s.
Industrial agriculture requires genetic uniformity. Vast areas are typically planted to a single, high-yielding variety or a handful of genetically similar cultivars using capital intensive inputs like irrigation, fertilizer and pesticides to maximize production. A uniform crop is a breeding ground for disaster because it is more vulnerable to epidemics of pests and diseases.
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