Human transformation of natural ecosystems for production of food, fiber, and fuel has occurred on a massive scale—cultivated systems now occupy 24% of Earth’s terrestrial surface and are the single greatest land use by humans.1 Although there are a wide variety of cultivated systems, this chapter focuses on those that constitute major providers of food, feed, or fiber or that have significant impacts on the provision of other ecosystem services, at regional or global scales. In this chapter, ecosystem services are divided into those that provide food, feed, fiber, and other cultivated outputs and ‘‘other services’’ that include, for example, biodiversity, fresh water, nutrient cycling, and cultural services. Despite a tripling of the human population in the twentieth century, global food production capacity more than kept pace with demand. In fact, per capita food supply increased while food prices decreased in real terms. (See Chapter 8.) At the turn of the millennium, cultivated systems provided around 94% of the protein and 99% of the calories in human diets (FAOSTAT 2003). At the same time, they represented a major source of income for the estimated 2.6 billion people who depend on agriculture for their livelihoods (FAOSTAT 2004). Despite these successes there are still many parts of the world, often the poorest, where the productive capacity of cultivated systems has stagnated or even declined in the face of increased food demand from growing populations. Local disruption of cultivation by drought, flood, pests, disease epidemics (crop, animal, or human), armed conflict, and social unrest can be catastrophic in human, economic, and environmental terms. The prospect of providing sufficient food to sustain another 2 billion people by 2020 has rightly focused attention on the very real threats to food security and income generation if the productivity of cultivated systems cannot keep pace with this demand. But food security and concern for the more than 852 million who currently go hungry each day (FAO 2004) are only part of the challenge faced by cultivated systems. Human well-being depends not only on a sufficient and safe supply of food, feed, and fiber but also on access to clean water and air, timber, recreational opportunities, cultural and aesthetic pleasure, and so on. Cultivation often has a negative impact on provision of these services. For example, cultivated systems tend to use more water, increase water pollution and soil erosion, store less carbon, emit more greenhouse gases, and support significantly less habitat and biodiversity than the ecosystems they replace. Hence, as the share of the world’s natural ecosystems converted for cultivation has increased, the overall supply of ecosystem services other than food, feed, and fiber has fallen (Wood et al. 2000), despite growing demand for these additional services. Cultivated systems are under increasing pressure, therefore, to meet the growing need for cultivated products as well as to supply an amount and quality of other ecosystem services. Appropriately responding to this ‘‘double burden’’ represents a critical, long-term challenge to modern agriculture (Conway 1999; Runge et al. 2003). This chapter assesses the global extent, distribution, and condition of cultivated systems with regard to their continued capacity to both deliver food, feed, and fiber and contribute to the broader range of ecosystems services on which human well-being depends.

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