Impacts of GM Crops on Biodiversity. Abstract.

Feeding the World
Are GM Crops fit for Purpose? If not, then what?
12th November 2008
Queen Elizabeth II Conference Centre, Westminster, London

Impacts of GM Crops on biodiversity – is this solely a GM issue?
Dr Brian Johnson, Devon, UK


This paper will explore the relationship between crops and biodiversity in farmed and natural landscapes, not only in the UK but in other parts of the world where arable farming is practised.

The development of GM crops has raised serious issues about how changes in cropping systems can impact on biodiversity, issues that were investigated by the UK farm scale evaluations of GM herbicide tolerant crops.  Other research has been conducted abroad on the biodiversity implications of GM insect resistant crops.  Some of this research has revealed large impacts on biodiversity of changes in cropping systems unrelated to their GM traits, emphasising the importance of prior assessment of changes in all novel cropping systems, whether GM or not.

This research has also shed light on the biodiversity impacts of the GM traits, and has raised questions about how conventionally-bred traits might interact with biodiversity by changing the way in which crops are grown.  Assessments of the biodiversity impacts of cropping systems before they are introduced are rarely done.  Ignorance of biodiversity impacts has led to the dramatic declines in farmland wildlife we have witnessed over the past 60 years, most of which have been caused by changes in cropping systems enabled by the development of novel crop varieties.  If GM crops are to become part of our arable enterprises, impacts of the crop management systems associated with them should be taken into account before they are introduced, not decades afterwards, when it may be too late to reverse any adverse impacts.  

Cropping systems associated with some GM traits may also have positive impacts on biodiversity, particularly if their use leads to reductions or elimination of pesticides and other methods used to combat plant pests and diseases.  These traits should not be dismissed simply because they are GM – in many parts of the world they could make a real difference to the viability of farming, especially in impoverished areas with poor soils and little rainfall.  Even in developed areas, such crops may be better for biodiversity than conventional intensive farming, and some traits such as fungal resistance may allow quasi-organic systems to be used in areas where multiple applications of fungicides are currently used.

Gene flow from GM crops has been extensively estimated for nearly 20 years, yet we have little knowledge of the impacts of gene flow on the genetics and ecology of recipient plants.  The paper will emphasise the importance of research in this area, especially research that reveals impacts of gene flow on fitness.  There have been few studies of this kind, but those that have been done highlight the facts that assessing fitness is very difficult, and that many transgenes are unlikely to impact on fitness in natural ecosystems.

But there are some transgenes, and their conventionally bred equivalents, that could affect fitness of recipient plants, especially in saline and arid environments. Theoretically some gene complexes, especially if stacked, could have significant ecological effects, but until research has investigated these issues, any predictions about the impacts of the transfer of “second generation” genes such as salinity and drought tolerance are speculative and should be treated with scepticism.



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