WHAT鈥檚 the worst thing that farmers do to the environment? Use pesticides?
Probably not. Plant genetically engineered crops? Not even close. It鈥檚 the
simple, time-honoured act of clearing land, draining water from it and ridding
it of unwanted biodiversity鈥攃ommonly known as weeds. Whether cleared by
hoe, plough or chemical herbicide, farmland is an ecological sacrifice zone.
Carol Shennan knows the grim reality better than most. She grew up in
Lincolnshire, in eastern England, where the hand of agriculture has left a heavy
mark. 鈥淢y father worked on draining some of the last salt marshes,鈥� says
Shennan. 鈥淗e thought it was a great thing.鈥� Half a world away from her childhood
home, his daughter is trying to do the opposite. She now directs the Center for
Agroecology and Sustainable Agriculture at the University of California, Santa
Cruz, and is working to put wild nature back on more equal terms with
farming.
In the mid-1990s, Shennan seized the chance to put her ideas into practice in
the Tule Lake basin of north-eastern California. Nestled in a high valley, more
than a kilometre above sea level, the basin is home to a large overwintering
population of bald eagles, the US鈥檚 national bird. Each fall and spring,
millions of geese and ducks stop near the lake on their annual migrations along
the Pacific flyway. Yet close by the lake, taking up much of the wide, nearly
flat valley, were the same fields of potatoes, wheat and barley that Shennan
recalled from Lincolnshire. And these fields, too, had been created by draining
wetlands.
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In contrast to Lincolnshire, though, the conflict between agriculture and
nature at Tule Lake was open and raw. The US government, which owns the entire
area, had declared the basin a national wildlife refuge, but for almost a
century it had leased two-thirds of the land to farmers. The remaining third of
the land, 5000 hectares, was set aside as wild wetland. But the compromise
hadn鈥檛 worked. Bird populations had plummeted to one-third their pre-1970 level,
and ecologists said that there was simply too little wetland left in the basin.
Environmentalists demanded that farming in the basin be curtailed drastically,
with a predictable response from farmers. 鈥淪ave the World. Shoot an
Environmentalist,鈥� read the bumper stickers when Shennan began visiting the
area. 鈥淭he polarisation and hostility were palpable,鈥� she recalls.
Yet Shennan nurtured the hope that environmentalists and farmers could figure
out ways to manage the land to the benefit of both. This hope was not,
initially, widely shared around Tule Lake. 鈥淚 usually found myself yelled at
from both sides,鈥� Shennan says. The farmers weren鈥檛 inclined to trust a foreign
researcher, while environmentalists thought she had too much sympathy for
agriculture.
As it turned out, however, Tule Lake offered a rare opportunity for
cooperation. While the wetlands, deprived of their periodic flooding, were
gradually drying up, it was not just the wildlife that was suffering: the
fields, too, were becoming less fertile and increasingly infested with nematode
worms, a major crop pest.
Government officials in the area had already begun pondering a radical
solution, intended to solve both problems at once. Because the government owned
all the land, it could redesignate agricultural areas as wildlife reserves, and
vice versa. It proposed to flood some of the fields, turning them into fresh
wetlands, while draining an equal area of existing marshes and converting them
to agriculture. Freshly flooded fields, the federal officials thought, might
make better habitat for waterfowl, and freshly drained wetlands should provide
highly fertile and pest-free soil.
鈥淚 thought it was crazy at first,鈥� recalls Shennan. She could imagine many
unwelcome consequences of the plan, such as a sudden release of nitrogen and
phosphorus from the flooded agricultural fields into the waters of Tule Lake. No
one knew how quickly wetlands could be converted into farmland and back again.
To minimise the risks, Shennan persuaded the government to start with small
parcels of between 15 and 55 hectares.
She also brokered conversations between the warring tribes that made up the
Tule Lake community, and helped convince farmers to cooperate with naturalists.
鈥淚 told the farmers the story of where I came from,鈥� Shennan says. 鈥淚 don鈥檛
believe in value-free science. We all have values and beliefs, and my belief is,
we can design a system that allows agriculture and wildlife to coexist.鈥� In the
end, many of the farmers, desperate for a way to preserve agriculture around
Tule Lake, decided to participate in the land swap. The experiment got under way
in 1995.
Shennan鈥檚 goal of promoting greener agriculture has plenty of other
enthusiasts, too, especially in Europe. Renate K眉nast, Germany鈥檚 Minister
for Consumer Protection, Food and Agriculture, is leading the campaign to spend
more on 鈥渁gri-environmental鈥� schemes aimed at subsidising organic production or
maintaining 鈥渟emi-natural鈥� landscapes such as hedgerows, wetlands and
heathlands.
However, it鈥檚 often unclear what these programmes accomplish. In Europe, some
of the funding goes to preserve stone walls and olive groves because of their
historical and aesthetic value, rather than any ecological significance.
Subsidies for organic production, too, may create little additional habitat for
wildlife. A recent paper prepared by the European Commission鈥檚
Directorate-General on Agriculture recommended a more systematic approach.
Policy makers should start by setting environmental goals region by region, the
paper says. Only then should they decide how much land to hold back from
agriculture to reach those goals, and what subsidies and other policies they
need.
This sounds good in theory, but it doesn鈥檛 answer the big question: can
intensive agriculture ever coexist with ecosystems that are vibrant and diverse?
And how much land would have to be set aside to achieve this? The truth is, no
one knows.
One large-scale agri-environmental programme in the US, however, has become
an enormous open-air laboratory for researchers trying to answer such questions.
The Conservation Reserve Program, which was revised to promote wildlife
conservation five years ago, has paid American farmers to plant trees or native
grasses on about 13 million hectares of former crop land鈥攁n area the size
of England. Individual farmers, not regional planners, decide how much land to
set aside, and where. By comparing regions where farmers have made different
choices, scientists have begun to get a sense of what works and what
诲辞别蝉苍鈥檛.
One clear finding is that it makes a huge difference how the set-aside land
is configured. For example, native bird species generally shun blocks of prairie
smaller than 15 hectares, and the biggest benefits kick in at about 65 hectares.
鈥淚f I was engineering it, I鈥檇 want to create clusters of large blocks,鈥� says
William Clark of Iowa State University鈥檚 Department of Animal Ecology. And that
may turn out to be easier than it sounds, because large blocks of land emerge
naturally if farmers set aside a large enough share of the land, says Clark.
Clark has studied the effects of set-asides in Iowa on ringneck
pheasants鈥攁n introduced species, but one that serves as a useful indicator
of wildlife habitat because the birds are so easy to count. The biggest gains in
pheasant populations, he finds, come as the percentage of wildlife habitat in a
given county rises from 5 to 15 per cent. Below 5 per cent, there鈥檚 too little
habitat to make much difference. Above 15 per cent, each new hectare of
additional habitat adds a diminishing amount of benefit. Studies of waterfowl
and other wildlife suggest a similar threshold.
Of course, not every species can coexist with agriculture鈥攚olves in
sheep-farming areas spring to mind as an example. 鈥淭hat鈥檚 why those species were
extirpated in the first place,鈥� says Ed Hackett, from the government-funded
Wildlife Habitat Management Institute. And in the eastern US, where it costs
more to convince farmers to set aside land for wildlife habitats, set-asides
have been less successful. 鈥淲e鈥檝e been unable to establish large enough blocks
of land to sustain populations of bobwhite quail,鈥� says Tom Franklin of The
Wildlife Society, a private research group. Nor do even the best set-asides
approach the truly 鈥渘atural鈥�. Apart from the rarity of large carnivores,
set-asides must usually be managed actively鈥攂y periodic burning, for
instance鈥攚hich means someone must make choices that favour some species to
the detriment of others.
Still, if Clark鈥檚 5-to-15 per cent rule holds for most or even many species,
that鈥檚 good news for some regions. In hilly southern Iowa, wildlife habitat
already accounts for 12 per cent of the land area, and several other parts of
the US probably do equally well. In England and Wales as a whole, over 20 per
cent of the land surface is in forest, bog, bracken or other seminatural state.
The proportion is even higher in Scotland. But other areas fall far short of the
ideal. The flat, fertile north of Iowa, for example, is only about 3 per cent
wildlife habitat.
In an ideal world, farmers in a particular area would work together to create
larger conservation set-asides than they could separately. Yet such cooperation
is rare and fragile. In the Tule Lake basin, for example, the experiment worked
beautifully at first. Ducks and geese preferred the newly flooded areas, which
rapidly produced lush stands of wetland vegetation. A quarter of all the
waterfowl in the entire refuge were found in the former fields, which
represented only four per cent of the total wetland area. And when a few of
these flooded areas were farmed again after three years, farmers found the soil
richer in crucial nutrients and completely free of nematodes. Agriculture could
indeed live side-by-side with nature to the benefit of both.
But this happy coexistence didn鈥檛 last鈥攖hough for reasons that had
nothing to do with wetland birds or crop pests. 鈥淚t all got derailed last year,鈥�
says Shennan. It fell victim to a battle over rights to the water in Tule Lake
and the Klamath River, which drains the lake. As drought gripped the region and
the Klamath River鈥檚 water level fell, federal officials gave top priority to
protecting the river鈥檚 coho salmon. They cut off irrigation water to the farmers
in the Tule Lake basin, dashing any hopes of a harvest. Feeling betrayed by the
government, the farmers broke the locks on irrigation gates, allowing prohibited
water to flow into their fields. Local police refused to intervene, leaving it
up to federal officials to enforce their water policy. 鈥淎 lot of the goodwill we
were developing has been lost,鈥� says Shennan.
The final, unpleasant lesson of her experience in California seems to be that
opening up room for wildlife within agriculture is a matter of economic and
political power. The Tule Lake experiment shows that farmers and
environmentalists truly can work together to reshape agriculture into a form
more compatible with nature. But it also shows that holding onto those gains
will require a still wider coalition.