Forests and Rainforests

A forest, as defined by the Food and Agriculture Organization of the United Nations, is land greater than half a hectare in area with trees taller than five meters and a canopy cover of more than ten percent. Under this common reporting definition, the world held approximately 4.06 billion hectares of forest in 2020. Just over half of that total was concentrated in five countries: the Russian Federation, Brazil, Canada, the United States of America, and the People's Republic of China. Forest cover varies enormously across the globe, from the near-total tree cover of parts of the Amazon, Congo, and Southeast Asian lowlands to the scattered woodlands of the Sahel and the almost treeless expanses of the polar regions and the great deserts.

Ecologists generally group the world's forests into three broad biomes defined by latitude and climate. Tropical forests, found in the humid belt near the equator, include both the famous evergreen rainforests and the seasonally dry tropical forests that lose their leaves during the dry season. Temperate forests, located in the mid-latitudes of both hemispheres, mix deciduous and coniferous trees and pass through four seasons. Boreal forests, sometimes called taiga, form a nearly continuous band of conifer-dominated woodland across the high latitudes of the Northern Hemisphere, from Scandinavia across Russia and on through Canada and Alaska. A fourth, smaller category, the coastal mangrove forest, occupies the intertidal zone of tropical and subtropical shorelines.

Forests are more than collections of trees. They are intricate communities of plants, animals, fungi, microbes, and soils that evolved over tens of millions of years and that perform functions essential to human life. They pull water from the soil and return it to the atmosphere through transpiration, fueling rainfall hundreds or thousands of kilometers downwind. They store vast quantities of carbon in wood, leaves, and soil, making them central players in the global carbon cycle. They harbor the majority of the world's terrestrial biodiversity, and they supply timber, food, fiber, fuel, and medicine to an estimated 1.6 billion people who depend directly on them for some part of their livelihoods. The health of the world's forests is therefore a matter of both ecology and human welfare.