The Roman poet Catullus lamented the death of a pet sparrow, probably a house sparrow or a tree sparrow. In either case, a present-day Catullus would have ample cause for lamentation. Both kinds of sparrows are among the many species of birds, insects and plants that have declined dramatically in Northern Europe during the past 25 years.
It is estimated that, in the past 20 years, ten million breeding individuals of ten species of farmland birds have disappeared from the British countryside. The decline in bird numbers in part [1](1. reflects 2. reviews 3. revises) the decline of those insects and plant populations upon which they depend.
[2](1. Opposite 2. Particular 3. Parallel) changes have taken place in many other European countries, although these have not been documented in as much detail as in Britain, where censuses are carried out by the British Trust for Ornithology (BTO). In all, 116 species of farmland birds — one fifth of European birds — are now of conservation concern.
Rachel Carson’s classic 1963 books Silent Spring [3](1. announced 2. alerted 3. altered) the public to the toxic side effects sofa insecticides, such as DDT, that had fueled the green revolution. Traces of these chemicals were found to persist in the food chain, reaching higher [4](1. worries 2. concentrations 3. weights), and hence having more severe effects, at successive levels in the food chain. They were identified as the cause of rapid population decline in birds of prey, such as falcons and hawks, through the thinning of eggshells. The offending chemicals have now been [5](1. phased out 2. accumulated 3. retained) in the United Kingdom and many other countries, but their use is still increasing in some parts of the world.
The new losses in biodiversity are sometimes called the “second Silent Spring.” However, although they are [6](1. comparable 2. concerned 3. associated) with the intensification and industrialization of agriculture, they involve more subtle and indirect effects than the poisoning of wildlife by insecticides. In general terms, intensification refers to making the greatest possible proportion of primary production available for human consumption. To the [7](1. area 2. amount 3. extent) that this is achieved, the rest of nature is bound to suffer.
Can we be sure that the bird declines in the United Kingdom are caused by agricultural intensification? Although the cause of these declines has not been proven, there are some suggestive figures. For example, annual BTO censuses of 42 species of breeding birds show that 13 species living [8](1. exclusively 2. prevalently 3. geographically) in farmland declined by an average of 30% between 1968 and 1995, while 29 species of birds that can live anywhere have increased by an average of 23%.
The changes in British agriculture over the past 30 years, which have many parallels with other parts of the world, have sought to increase production and productivity. The success of the green revolution in achieving this is undeniable. In spite of rapid population growth, about 25% more food per person is produced now than 30 years ago. However, the need to conserve wildlife [9](1. in comparison with 2. in opposition to 3. in harmony with) agriculture is beginning to be recognized. Reforms have been proposed that will reduce the incentive for production and allow other important considerations, such as environmental benefits, to come into play. But the proposals as they stand are [10](1. totally clear 2. virtually silent 3. completely sound) about what environmental benefits are expected and how they will be achieved.
The United Kingdom has three agricultural schemes that could have benefits for [11](1.intensification 2. biodiversity 3. revolution). Two of these schemes, the Environmentally Sensitive Areas and the Countryside Stewardship Scheme, both subsidize* farmers to preserve traditional landscape features. Between them they cover about 12.5% of agricultural land. Unfortunately, there are few data to [12](1. demonstrate 2. experiment 3. authorize) whether or not these schemes have benefits for biodiversity, although some habitats have been preserved or restored. A third scheme, “set-aside,” subsidizes farmers to leave some fields uncultivated. The available data show that set-aside can be beneficial for birds and other wildlife. But set-aside will probably be discontinued early in the 21st century. Although we can, as described above, devise schemes that may help a traditional environment or individual species to [13](1. recover 2. conserve 3. adhere), there appears to be no single program or combination of programs that can reverse the decline in a large general population such as farmland birds. Therefore, the most general prescription seems to be to reverse the intensification of agriculture as a whole.
A slightly more specific prescription comes from the habitat heterogeneity and lower intensive agriculture found in the concepts of organic farming. Although several comparisons of organic and conventional farms have [14](1. recommended 2. Suggested 3. Guaranteed) that organic farming is good for biodiversity, this benefit probably relates to such features as crop diversity and maintenance of natural field borders rather than to any “belief” in organic farming. Although there have been no systematic comparisons of the biodiversity benefits of organic and other “wildlife friendly” farming methods, it seems that heterogeneous landscapes are good for birds.
On a larger scale, there are unresolved questions for conservation ecology about the [15](1. moral values 2. policy decisions 3. relative merits) of a less intensive, more environmentally friendly agriculture throughout the countryside on the Eastern European model versus a highly intensive agriculture in breadbasket regions with separate, large nature reserves on the North American model. The United Kingdom is probably too small for the North American model, but one could imagine some form of it on a Europe wide basis, especially if reduced subsidies were to make agricultural production [16](1. unresponsive 2. unrealized 3.uneconomic) in some areas, and instead conservation were to be subsidized.
In the United Kingdom, as in most of Europe, people have made the landscape. This means that the characteristic habitats and species that conservationists wish to preserve are generally there because of traditional land management rather than [17](1. in spite of 2. in conjunction with 3. in consequence of) it. The future shape and purpose of the countryside is society’s choice. At present, most of those in the United Kingdom who voice an opinion would prefer a countryside in which agricultural production is moderated with conservation. And on a worldwide stage this makes sense for a sustainable future: the green revolution gave success at a price, and that price cannot be paid [18](1. finally 2. indefinitely 3. absolutely).
The British public’s concern about genetically modified (GM) crops, based in part on justifiable environmental concerns, must be placed in this context. Whatever hazard GM crops may pose to the environment is linked to the general problem of biodiversity in a landscape damaged by the intensification of agriculture. The environmental safety aspects of GM must be thoroughly investigated to define the [19](1. risks 2. profits 3. degrees) before moving to large-scale commercial planting. Even then, we must continue careful observation and evaluation. But we must also recognize a potential benefit of GM crops — to give us a wider range of options as we try to make a more [20](1. heterogeneous 2. sustainable 3. intensive) future for agriculture than that created by the last green revolution.
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