In Part IV we intend to select a number of food-related issues and discuss them under the umbrella of ‘political ecology’. Rather than a coherent theory, this is a broad conceptual framework that encourages studies of the interface between nature and society, where political economy meets ecology. Its first strand is a concern for the environmental change wrought by food producing activities such as agriculture and food processing. A number of the major themes of environmental management, such as agroecosystem modification, soil erosion, deforestation, desertification, and pollution, are relevant here but we will not follow them up because there are already a number of excellent existing texts (for instance Blaikie 1985; Blaikie and Brookfield 1987; Mannion 1995; Bryant and Bailey 1997).