Environmental impact of genetically modified crops.

Chapter 11 (Page no: 240)

Biodiversity and genetically modified crops.

Biological diversity (biodiversity) has emerged in the past decade as a key area of concern for sustainable development. At its highest level of organization, biodiversity is characterized as ecosystem diversity, which can be classified in the following three categories: natural ecosystems (ecosystems free of human activities); semi-natural ecosystems (in which human activity is limited); managed ecosystems (systems that are managed by humans to varying degrees of intensity from the most intensive, conventional agriculture and urbanized areas, to less intensive systems including some forms of agriculture in emerging economies). Yet, despite its importance, biodiversity in agriculture, i.e. crop biodiversity, which represents a variety of food supply choice for balanced human nutrition and a critical source of genetic material allowing the development of new and improved crop varieties, is rarely considered. Species and genetic diversity within any agricultural field will inevitably be more limited than in a natural or semi-natural ecosystem. Biodiversity in agricultural settings is particularly important in areas where the proportion of land allocated to agriculture is high, as seen in continental Europe. Under these circumstances, changes in agrobiological management will have a major influence on biodiversity. Innovative thinking about how to enhance biodiversity on the level of regional landscapes, coupled with bold action, is thus critical in dealing with the loss of biodiversity. Biodiversity should act as a biological insurance for ecosystem processes, except when mean trophic interaction strength increases strongly with diversity. The conclusion, yet to be validated from field studies, is that in tropical environments with a natural high biodiversity the interactions between potentially invasive hybrids of transgenic crops and their wild relatives should be buffered through the complexity of the surrounding ecosystems. Taken together, theory and data suggest that compared to intertrophic interaction and habitat loss, competition from introduced species is not likely to be a common cause of extinctions in long-term resident species at global, metacommunity and even most community levels.

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