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Boreal forest near Shovel Point in Tettegouche State Park, along the northern shore of Lake Superior in Minnesota.. A boreal ecosystem is an ecosystem with a subarctic climate located in the Northern Hemisphere, approximately between 50° and 70°N latitude.
Fire is the dominant type of disturbance in boreal North America, but the past 30-plus years have seen a gradual increase in fire frequency and severity as a result of warmer and drier conditions. From the 1960s to the 1990s, the annual area burned increased from an average of 1.4 to 3.1 million hectares per year.
Ecoregions of North America, featuring the 50 United States, the District of Columbia and the five inhabited territories. The following is a list of ecoregions in the United States as identified by the World Wide Fund for Nature (WWF). The United States is a megadiverse country with a high level of endemism across a wide variety of ecosystems.
Age of the bedrock underlying North America, from red (oldest) to blue, green, yellow (newest). Seventy percent of North America is underlain by the Laurentia craton, [5] which is exposed as the Canadian Shield in much of central and eastern Canada around the Hudson Bay, and as far south as the U.S. states of Michigan, Wisconsin, and Minnesota.
In comparison with other biomes, however, the taiga has low botanical diversity. Coniferous trees are the dominant plants of the taiga biome. Very few species, in four main genera, are found: the evergreen spruce, fir and pine, and the deciduous larch. In North America, one or two species of fir, and one or two species of spruce, are dominant.
The Tundra of North America is a Level I ecoregion of North America designated by the Commission for Environmental Cooperation (CEC) in its North American Environmental Atlas. One of the planet's most recent biomes , a result of the last ice age only 10,000 years ago, the tundra contains unique flora and fauna formed during the last glaciation ...
The North American Desert biome is facing a variety of ecological threats. Human disturbance poses the number one concern to this fragile ecosystem. The Sonoran desert contains the two large cities of Tucson and Phoenix, Arizona, which contain over 3 million people. [15]
The life zone concept was developed by C. Hart Merriam in 1889 as a means of describing areas with similar plant and animal communities. Merriam observed that the changes in these communities with an increase in latitude at a constant elevation are similar to the changes seen with an increase in elevation at a constant latitude.