Pilot Analysis Of Global Ecosystems: Agroecosystems

The PAGE Agroecosystems study analyzed qualitative and quantitative indicators of the condition of the world’s agroecosystems in terms of the delivery of a number of key goods and services valued by society. These goods and services include food, feed and fiber; water services; biodiversity; and carbon storage. The PAGE study also attempted to assess the state of the underlying soil resource conditions, both as a determinant of agroecosystem capacity to produce goods and services and as a consequence of agroecosystem management practices.

Agroecosystems are defined as “a biological and natural resource system managed by humans for the primary purpose of producing food as well as other socially valuable nonfood goods and environmental services.” The reports looks at the global extent of agricultural lands- land with 30 percent or greater agricultural activity- using a satellite-derived land cover database. Indicators of condition and value of agricultural and environmental goods and services were determined in consultation with agroecosystem experts in consideration of data limitations. Wherever possible, the spatial distribution of indicator values was shown within the satellite-derived global extent of agriculture.

Results show that, although food production has more than kept pace with population growth it has done so at the expense of biodiversity, clean water, carbon storage capacity and the quality of soils. Twenty to 30 percent of the world’s forest areas have been converted to agriculture, resulting in extensive species and habitat loss. Soil degradation, including nutrient depletion, erosion, and salinization, is widespread. Salt accumulation in soils has damaged 45 million hectares of agricultural land, representing some 20 percent of the world’s total irrigated land. An additional 1.5 million hectares are damaged each year due to salinization. Agriculture consumes 70 percent of the freshwater withdrawn annually by humans. Irrigation is draining more water than is being replenished by rainfall, causing water tables to fall. Moreover, many water sources are being polluted by excessive use of fertilizers and pesticides. For these trends to change, agricultural lands need to meet the double challenge of increasing food production while continuing to provide much-needed environmental goods and services.