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Agriculture and Biodiversity

Decline of species diversity threatens agriculture

The improvement of plant species is a big business in Saskatoon, with several major agricultural institutions employing hundreds of plant scientists and technicians. Another growing industry in Saskatoon involves the use of plants to make medicines or nutraceuticals foods with medicinal properties.

Both of these industries are ultimately dependent on the genetic resources of the planet's diverse plant species. That is why scientists are increasingly alarmed at the elimination of thousands of plant species that may contain genes useful in plant development.

According to a new report from Worldwatch, Nature's Cornucopia: Our Stake in Plant Diversity by John Tuxill, changes in agriculture are resulting in diversity slipping away.

In China, says Tuxill, farmers were growing an estimated 10,000 wheat varieties in 1949, but were down to only 1,000 by the 1970s. And Mexican farmers are raising only 20 percent of the corn varieties they cultivated in the 1930s. The wider the varietal diversity, the more options our plant breeders have when looking for genes to help give resistance to new diseases or insect pests.

Tuxill says plant loss extends far beyond agriculture. One in every four medicines prescribed in the United States is based on a chemical compound originally found in a plant. And worldwide some 3.5 billion people in developing countries rely on plant-based medicine for their primary health care. Plants also furnish oils, latexes, gums, fibers, timbers, dyes, essences, and other products we use every day. Rural residents of developing countries depend on plant resources for up to 90 percent of their total material needs.

The reasons for the rapid pace of species loss include loss of habitat, pressure from non-native species, and over harvesting, Currently, one out of every eight plant species is at risk of extinction, according to the World Conservation Union.

Tuxill points out that it is not just obscure or seemingly unimportant plants that are in trouble. For example, some two thirds of all rare and endangered plants in the United States are close relatives of cultivated species. Crop breeders often turn to wild relatives of crops for key traits, like disease resistance, when they cannot find those traits in cultivated varieties.

Many medicinal plants are also in trouble from over harvesting and destruction of habitat. One example is the African cherry tree, the bark of which is widely used in Europe for treating prostate disorders. The medicinal trade has led to severe depletion of the tree. Since less than 1 percent of all plant species have been screened for bioactive compounds, every loss of a unique habitat and its species is potentially a loss of future drugs and medicines. And traditional knowledge about medicinal plants is declining even faster than the plants themselves.

Gene banks, botanical gardens, and protected areas, the first lines of defense in maintaining the diversity of plant life, are themselves threatened by government spending cutbacks. Today, for example, only 13 percent of gene-banked seeds are in well-supported facilities with long-term storage capability.

As bleak as this picture is, there are readily available ways to slow or stop species loss, and many governments, NGOs, and citizen activists are developing innovative partnerships to strengthen plant. Examples identified by Tuxill include: