NSCI 1403 Lecture 29: Major Land Ecosystems of the Biosphere
27 Dec 2016
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Document Summary
Biomes change with altitude just as they do with latitude because vegetation is partly determined by temperature. Precipitation also plays a significant role, which is one reason grasslands, instead of tropical or deciduous forests, are sometimes found at the base of mountains. The arctic tundra encircles the earth south of the ice-covered polar seas in the northern. Trees are not found in the tundra because: the growing season is too short, their roots cannot penetrate the permafrost, and, trees cannot become anchored in the boggy soil of summer. Birds harvest the seeds of conifers; bears, deer, moose, beaver, and muskrat live around the cool lakes and streams. Major carnivores include wolves, wolverines, and mountain lions. The temperate rainforest along the pacific coast has the largest trees in existence, some as old as 800 years. Tropical rain forests are found in south america, africa, and the indo-malayan region near the equator.
