Post‐war changes in arable farming and biodiversity in Great Britain

Abstract

Summary 1.Agriculture represents the dominant land use throughout much of western Europe, and a significant part of European biodiversity is associated with this habitat. We attempted to quantify the changes in agriculture and biodiversity in Britain since the 1940s. 2. There have been widespread declines in the populations of many groups of organisms associated with farmland in Britain and north-west Europe. The declines have been particularly marked amongst habitat specialists; many of the taxa still common on farmland are habitat generalists. 3. Farming practices have become increasingly intensive in the post-war period, with a dramatic reduction in landscape diversity. Since 1945, there has been a 65% decline in the number of farms, a 77% decline in farm labour and an almost fourfold increase in yield. Farms have become more specialized; the greatly increased use of machinery has made operations quicker and more efficient, but has resulted in the removal of 50% of the hedgerow stock. Autumn sowing of crops has become predominant, with winter stubbles now far less prevalent. The number and extent of chemical applications has increased greatly, but the net amount applied, and their persistence, has decreased in recent years. 4. Intensification has had a wide range of impacts on biodiversity, but data for many taxa are too scarce to permit a detailed assessment of the factors involved. Reduction in habitat diversity was important in the 1950s and 1960s; reduction in habitat quality is probably more important now. 5. As a case study, the declines in populations of seed-eating birds populations were assessed in relation to changing agricultural management. Generally, the declines were likely to be caused by a reduced food supply in the non-breeding season, although other factors may be important for particular species. 6. Agriculture will face a number of challenges in the medium term. While research into the mechanisms underlying species and habitat associations, and their interaction with scale, will be critical in under-pinning management, consideration of farmer attitudes and socio-economic factors is likely to be as important. Biodiversity may benefit from integrated farming techniques but these need to incorporate environmental objectives explicitly, rather than as a fringe benefit.

Spatial diversification of agroecosystems to enhance biological control and other regulating services: An agroecological perspective

“…These external inputs also decrease the flow of regulating services (e.g. pest control, pollination, water flow regulation, carbon storage) (Foley et al, 2005;Robinson and Sutherland, 2002). The challenge remains in mobilising functional agrobiodiversity able to provide regulating services for producing resources with fewer external inputs and with a limited provision of disservices (Power, 2010;Zhang et al, 2007).…”

Ecological Impacts of Genetically Modified Crops: Ten Years of Field Research and Commercial Cultivation

“…Taking into account that all three crops occupied less than 15% of the total arable field surface of Great Britain in any year [135], it is unclear if these effects would occur at the landscape-level and how significant they would be. A major factor in the decline in farmland biodiversity over the last decades has been the loss of more specialized taxa [8]. Thus, many of the birds and butterflies that declined markedly in the period prior to 1970 were dependant on areas of extensive low-input cultivation or the presence of noncropped habitat.…”

“…In general, the plants currently common on arable land are found in a wide range of other habitats. Similarly, butterflies as well as the non-declining farmland birds now typical of farmland in Britain are those that tend to be habitat generalists [8]. More intensive field management, degradation in habitat quality, and increasing habitat homogeneity (across all-scales) are currently the most important drivers of biodiversity loss.…”

“…Substantial scientific data on environmental effects of the currently commercialized GM crops are available. Independent from the use of GM crops, modern agricultural systems have considerable negative impacts on global biodiversity [6][7][8][9][10][11]. On a global scale, the most direct negative impact is due to the considerable loss of natural habitats, which is caused by the conversion of natural ecosystems into agricultural land [9,12].…”

“…Modern agricultural systems have produced a landscape in which many fields have very few weeds and very few invertebrates providing little food for birds. The shift in the type and density of weeds in the fields, as well as the disappearance of important habitats such as large stretches of hedgerows, was mainly responsible for the dramatic decline in bird populations [8,14,15]. Potential impacts of GM crops should thus be put in relation to the environmental impacts of modern agricultural practices that took place over the last decades.…”