The Princeton Guide to Ecology

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.

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.

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