How to Classify Biomes by Latitude

Classify the high-latitude biomes of Arctic tundra and boreal forests in the Northern Hemisphere. The former ecological community, dominated by short-growing grasses, sedges, lichens and mosses and roamed by creatures like caribou and musk-oxen, is roughly tied to the polar climate type. Such climates are defined by sparse precipitation, long winters of extended night and short summers of near-constant sunlight. Meanwhile, the boreal forest, or taiga, is an enormous region of forest -- mainly dominated by conifers -- associated with a subarctic climate between the Arctic and temperate zones of the Northern Hemisphere. A tree line defines the frontier between the taiga and the tundra, where increasingly stunted trees finally give way to open, rolling country because of permafrost (permanently frozen soil) and other climatic limitations.

Identify the temperate biomes of the world in their mid-latitude positions in the Northern and Southern Hemisphere. The most extensive are the midlatitude grasslands or steppe and the midlatitude deciduous forests. Rolling temperate-zone steppe covers huge parts of the North American and Eurasian interior as well as portions of South America, Africa and Australia. Often these biomes are dominated by perennial grasses or hardy shrubs well-adapted to limited precipitation, hot summers, cold winters and the chronic presence of wildfire. Regions in the temperate zone with more generous rainfall often produce deciduous forest dominated by trees that lose their leaves for part of the year in response to the winter season.

Catalog the biomes of the tropical belt of the planet, a region experiencing climatic influences highly distinct from higher-latitude locations, set between the latitudes of the Tropic of Cancer and the Tropic of Capricorn. Some of the most diverse ecosystems on Earth flourish here, including the tropical-rainforest biome subject to a relatively constant yearly climate of high temperatures and precipitation. Tropical rainforests are most extensive in northern South America, central Africa and southeastern Asia. Tropical scrub and savanna are swaths of grassland, open woodland and semi-arid brush under climates of more variable rainfall, while tropical deciduous forest often fringes true rainforest.

Consider the geography of deserts. Not all are strongly linked to latitude, being dictated by topographic factors like a rainshadow-casting mountain range. But the most extensive deserts lie in the subtropical latitudes associated with dry, descending air masses that strongly limit precipitation. This zone includes the world's largest desert, North Africa's Sahara.