restricted access VII.7 Agriculture, Land Use, and the Transformation of Planet Earth
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VII.7 Agriculture, Land Use, and the Transformation of Planet Earth Jonathan A. Foley, Chad Monfreda, Jonathan A. Patz, and Navin Ramankutty OUTLINE 1. What are we farming? Geographic patterns of major crop types 2. How are we farming? Changing agricultural management 3. Agriculture as a force of global environmental change 4. Summary and conclusions It is fair to say that our planet’s most precious resource is land. Land is the source of the vast majority of our food and fresh water, nearly all of our fiber and raw materials, and many other important goods and services. It is also our home. But our relationship to the land has been dramatically changing over the history of our species, mainly through the invention and evolution of agriculture. Today, with the emergence of modern agricultural practices, coupled with the population growth and technological developments of recent centuries, we have transformed a staggering amount of the Earth’s surface into highly managed landscapes. Even more startling: the widespread use of irrigation and chemical fertilizers has fundamentally altered the flows of water and nutrients across large regions of the globe. These modifications to the land have driven fundamental changes to the ecology of our planet. Even the effects of future climate change may not have such a major, transformative effect on the environment and on human society as agriculture . However, despite the importance of agriculture in the global environment, we still know relatively little about how it affects ecological systems across local, regional, and global scales. GLOSSARY cropland. Land used for growing crops. The UN Food and Agriculture Organization defines this as the sum of arable lands and permanent crops. Arable land is defined by FAO as including ‘‘land under temporary crops (double-cropped areas are counted only once), temporary meadows for mowing or pasture, land under market and kitchen gardens, and land temporarily fallow (less than 5 years). The abandoned land resulting from shifting cultivation is not included in this category. Data for arable land are not meant to indicate the amount of land that is potentially cultivable.’’ Permanent crops are defined as ‘‘land cultivated with crops that occupy the land for long periods and need not be replanted after each harvest, such as cocoa, coffee, and rubber; this category includes land under flowering shrubs, fruit trees, nut trees and vines, but excludes land under trees grown for wood or timber.’’ extensification. The practice of increasing the amount of agricultural land that is under cultivation. human appropriation of net primary production (HANPP). How much of the biological productivity of a given location is used, consumed, or co-opted by human activities. intensification. The practice of stimulating more agricultural production per unit area, mainly through increasing use of agricultural chemicals, irrigation water, high-yielding plant varieties, and machinery. land cover. Describing the physical state of the land surface, such as ‘‘rainforest,’’ ‘‘cropland,’’ or ‘‘desert.’’ land use. The practices employed on a particular piece of land, such as rotating grazing or intensive maize cultivation. net primary production (NPP). The biological productivity of the landscape, that is, the rate of conversion of physical energy (sunlight) into biological energy (through photosynthesis) in a given location. pasture. Agricultural land used for animal grazing. The UN FAO defines this category as ‘‘land used permanently (5 years or more) for herbaceous forage crops, either cultivated or growing wild (wild prairie or grazing land). The dividing line between this category and the category ‘Forests and woodland ’ is rather indefinite, especially in the case of shrubs, savannah, etc., which may have been reported under either of these two categories.’’ Since the dawn of agriculture, some 9000 years ago, humans have progressively transformed the landscapes of our planet. Over time, agricultural land use steadily spread across the globe, reaching into nearly every region, setting the stage for an explosion of agricultural activity after the rise of the Industrial Revolution. Equipped with new technologies, and rapidly increasing population and income levels, agriculture quickly expanded to meet increased food demand over the last 300 years (see plate 23). But this global expansion of farmland was not uniform. Instead, it has traced a path determined largely by the history of European economic and political control. In particular, the direct impact of European settlement was seen in the rapid expansion of agricultural land through North America, Argentina, South Africa, and Australia/New Zealand. The rest of the world also experienced significant cropland expansion as regions became connected...


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