During the next 50 years, global agricultural expansion
threatens to impact worldwide biodiversity on an
unprecedented scale that may rival climate change in
its significance for the persistence of a panoply of species
(Tilman et al., 2001). Predictions of an increase in the
human global population to around 9 billion (UN,
2003) could result in a further one billion hectares of
natural habitat, primarily in the developing world, being
converted to agricultural production, together with a
doubling or trebling of nitrogen and phosphorus inputs,
a twofold increase in the demand for water and a threefold
increase in pesticide usage. This is despite the likelihood of a net withdrawal of land from agriculture in the developed world