The Issues
The human population is growing at a rate of 90 million people per year; as a consequence, natural ecosystems are rapidly being replaced by agricultural systems and existing agricultural systems are being managed more intensely in order to keep up with the increasing demand for food. Over eight hundred scientists attending a meeting in Barcelona, Spain, on March 14-18, 1998, sponsored by the GCTE/LUCC Programs, will be discussing the environmental impact of converting natural and semi-natural ecosystems into intensively managed agricultural systems.

The Science

• The Food and Agriculture Organisation (FAO) of the United Nations estimates that 93 million hectares of land (an area about twice the size of Spain) will be converted to agricultural use by 2010 in South America, Africa, and Asia. Even with this increase in the area of land used for agriculture, production of wheat, rice and maize in developing countries will need to increase by about 250%, from 1 billion tonnes now to 2.5 billion tonnes by 2030, to meet rising demands for food.

• On the second day of the conference, Dr. P. J. Gregory, from the University of Reading, UK, and his colleagues will outline the environmental impact of this increase in agricultural production. They will use examples from the Sahel, Nepal and ?Slash and Burn? systems throughout the tropics to demonstrate the effects that both intensification and extensification will have on land and the long-term sustainability of crop production systems.

• Several new tools at the disposal of environmental scientists are helping them study the consequences of land use changes. Powerful computer programs called Geographical Information Systems (GIS) bring together a wide array of data including topography, hydrology, popu
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