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 idespread losses of plant species and varieties are
eroding the foundations of agricultural productivity and threatening
other plant-based products used by billions of people worldwide,
reports a new study by the Worldwatch Institute, a Washington,
DC-based research organization.  "Plants
provide us with irreplaceable resources," said John Tuxill,
author of Nature's Cornucopia: Our Stake in Plant Diversity.
"The genetic diversity of cultivated plants is essential
to breeding more productive and disease resistant crop varieties.
But with changes in agriculture, that diversity is slipping away."
In China, 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.
"Biotechnology
is no solution to this loss of genetic diversity," said
Tuxill. "We are increasingly skillful at moving genes around,
but only nature can create them. If a plant bearing a unique
genetic trait disappears, there is no way to get it back."
Loss of habitat,
pressure from nonnative species, and overharvesting have put
one out of every eight plant species at risk of extinction, according
to the World Conservation Union. "It is not just obscure
or seemingly unimportant plants that are in trouble," said
Tuxill. "Those that we rely upon most heavily are declining
too. 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.
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The
effects of plant loss extend 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.
Many medicinal
plants are also in trouble from overharvesting and destruction
of habitat. The bark of the African cherry tree is widely used
in Europe for treating prostate disorders, but the medicinal
trade has led to severe depletion of the tree where it grows
in the highlands of central African countries. Since fewer 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.
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Until
recently, gene banks, botanical gardens, and protected areas
have been the first line of defense in maintaining the diversity
of plant life. The world's 1,600 botanical gardens, for example,
collectively tend tens of thousands of plant species. But Tuxill
notes that these conventional approaches need significantly higher
levels of support. Many conservation facilities must scrape by
on increasingly scarce funding, particularly those run by national
governments. Only 13 percent of gene-banked seeds are in well-supported
facilities with long-term storage capability. Protected area
systems in many countries are also poorly developed.
As a result,
governments, NGOs, and citizen activists are developing innovative
partnerships to bring plant diversity back to the landscapes
where we live and grow our food and material goods. Tuxill identifies
a number of examples:
- In Iowa, a farmers' group and university
researchers are identifying agronomic practices, such as alternative
crop rotations and cover crop plantings, that can enhance biological
diversity on farms and save farmers money on fertilizers and
agrochemical inputs.
- Innovative plant breeders in developing countries
are working directly with farmers in participatory breeding programs
to evaluate, select, and improve locally adapted crop varieties
while maintaining robust levels of genetic diversity.
- Consumers can buy timber products from nearly
10 million hectares of forest worldwide certified as being managed
in an environmentally responsible manner under the guidelines
of organizations like the Forest Stewardship Council.
- In the Central American nation of Belize,
the government has established a rainforest reserve that is being
managed by a local association of traditional healers for the
production of wild medicinal plants.
- Throughout India, hundreds of thousands of
hectares of degraded forestland are recovering under co-management
arrangements between state forest departments and village associations.
Additional
steps need to be taken to reform policies and practices that
work against plant diversity. Some international bodies like
the Convention on Biological Diversity require governments to
develop policies for managing plant resources wisely. However,
others like the World Trade Organization demand that countries
dismantle these protective policies as barriers to free trade.
"The
bottom line is that we have to share both the economic benefits
of plant diversity and the obligation for protecting it,"
said Tuxill. "Those who garner the benefits of plant diversity,
such as agribusinesses and pharmaceutical consumers, should acknowledge
and support those who maintain it, like indigenous cultures and
national gene banks." Through benefit-sharing agreements,
international conservation endowments and grass-roots development
projects attuned to the links between cultural and biological
diversity, many options exist for supporting plant diversity
rather than diminishing it. 
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worldwatch.org; website www.worldwatch.org