Phil.Trans.R.Soc.Lond.B (2003) 358, 1775-1776 1775 ?2003 
The Royal Society, DOI 10.1098/rstb.2003.1412 (From Introduction)

By October 1998, four genetically modified crops had cleared most of the regulatory hurdles before commercial growing could be allowed in the UK. While these crops had been assessed as safe in terms of human health and direct impacts upon the environment, there had been insufficient research to determine whether there might be any significant effects on farmland wildlife resulting from the way that the crops would be managed (Advisory Committee on Releases to the Environment - ACRE -2000). The Farm Scale Evaluations (FSEs) of these genetically modified herbicide-tolerant (GMHT) crops were established to bridge this important gap in our knowledge, so illuminating the debate about their possible commercialization in the UK.

The use of broad-spectrum herbicides is not new to agriculture; for example, the herbicide glyphosate is widely used to kill the green cover of set-aside land before it is returned to cultivation. The FSEs compare the management of these GMHT crops with conventional crop management. The underlying issue is that conventional crop management has reduced the levels of some weeds to the point that there have been wider effects on farmland wildlife. For example, several species of farmland birds that feed on the weeds and their associated invertebrates have declined in numbers Will the changes in management associated with GMHT cropping exacerbate these trends, or might they result in benefits for farmland biodiversity?