World Biome Map
The World Biome:
The boreal forest is found in a nearly continuous belt across North America and Eurasia. Most of Canada and Russia are covered by coniferous trees that make up this biome. This biome is defined mainly by the trees that compose it.
The boreal forest corresponds with regions of subarctic and cold continental climate. There are long, severe winters and short summers (50 to 100 frost-free days), as is a wide range of temperatures between the lows of winter and highs of summer.
This biome has very characteric trees. Dominant trees in the the boreal forests are Needleleaf, coniferous trees. The four main trees found are: the evergreen spruce (Picea), fir (Abies), and pine (Pinus), and the deciduous larch or tamarack (Larix).
Arctic tundra is found almost entirely in the Northern Hemisphere. In the southern hemisphere it is found on isolated islands off the coast of Antarctica as well as the Antarctic peninsula. The tundra falls between two other major biomes, the boreal forest and ice caps.
In the arctic tundra there are two seasons: winter and summer. In the summer, the sun is present almost 24 hours a day. This sun however, only warms the tundra up to a range of about 3°C to 12°C. In the winter the opposite light conditions are present.
Forests in the temperate world experience a wide range of variability in temperature and precipitation. In regions where rainfall is broadly distributed throughout the year, deciduous trees mix with species of evergreens. Species such as oak, beech, birch, and maple.
Temperate grasslands are a division of a larger biome grouping of grasslands that includes tropical savannas. Both biome types are characterized by a dominance of grasses, yet temperate grasslands differ significantly from savannas. First unlike savannas that can have trees and shrubs scattered throughout, temperate grasslands have trees and shrubs absent. Temperate grasslands are also found in less tropical ecosystems and thus have a larger temperate fluctuation during the year. Temperatures in temperate grasslands can vary tremendously which has a large impact on growing seasons. Generally they also have less rainfall.
A desert is defined simply by the amount of rainfall that falls in an area and also with the amount of evaporation. In essence, its any area that receives on average less than 10 inches of rainfall per year, and where the yearly evaporation is more than 10 inches of rain a year.
Deserts are found around the globe, generally around a belt of 30 degrees north and south latitude where global wind patterns carry down dry air from the upper atmosphere.
Rainforests are defined by the amount and frequency of rain. To be a rainforest there must be at least 1750-2000 mm of rain a year and the rain must not be distributed extremely unevenly throughout the year.For example, certain tropical savannas receive rain only a few months a year in monsoon-like downpours.
Savannas are the tropical version of the temperate grasslands. Most savannas are caused by climatic patterns where there is a strong dry season for a large part of the year. Few trees survive in these regions, but most savannas do have some form of trees that scatter the landscape. Large tracks of savanna are found in South America, India and Australia.
The annual rainfall in a savanna is from 50.8 to 127 cm of rain a year. The rain must be concentrated in one season with a long period of drought in between. This drought causes the habitat to dry out which provides fires. These fires burn through the region and kill trees that may be trying to invade the grasslands.
The Alpine is not a biome that passes along large expanses of terrain like other biomes. This biome is not restricted to certain latitudes. It is not determined by temperature or rainfall either. Instead, this biome can be found at any latitude on earth. Its only dependent on elevation.
The tallest lifezone, the alpine can be found at any latitude on earth. yet, the elevation that the alpine begins is different depending on where you are.
For instance, on the tall Mexican Volcanos, the treeline is much higher than anywhere in the United states. It occurs around 13,000 feet.
In Colorado, the Tundra begins around 11,500 feet. Farther north, in Alaska, the Tundra can form at onlly a few thousand feet elevation!
Arid climates are those which average less than 10 inches of precipitation a year. Rainfall is highly localized and relatively unpredictable in terms of when it will occur, although usually there are seasons of highest probability for precipitation. Annual variation in total precipitation may also be great. Temperatures are also variable. They may exceed 100° F on summer afternoons, but dip by 20-30 degrees or more at night. Winters are cool to cold: "hot deserts" rarely experience frost; "cold deserts" may have prolonged periods of below freezing temperatures and snowfall.
Shrubs are the dominant growthform of deserts. They may be evergreen or deciduous; typically have small leaves; and frequently have spines or thorns and/or aromatic oils.
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