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In physical geography, tundra (/ ˈ t ʌ n d r ə, ˈ t ʊ n-/) is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. There are three regions and associated types of tundra: Arctic tundra, [ 2 ] alpine tundra , [ 2 ] and Antarctic tundra.
The adversity of soil and climatic conditions proves to low production levels, as well as little biomass accumulation due to slow rates of nutrient release in cold and wet soils, specifically as a result of limited nitrogen and phosphorus (Nadelhoffer et al. 1996) Additionally, there are low temperatures and strong winds in the tundra causing most vegetation to be dominated by woody plants ...
Many desert ecosystems are limited by available water levels, rather than rates of radiation or temperature. Water flow in these ecosystems can be thought of as similar to energy flow; in fact, it is often useful to look at water and energy flow together when studying desert ecosystems and ecology. [3]
Deserts and xeric (Ancient Greek ξηρός xērós 'dry') shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. [2] Ecoregions in this habitat type vary greatly in the amount of annual rainfall they receive, usually less than 250 millimetres (10 in) annually except in the margins.
Many desert animals (and plants) show especially clear evolutionary adaptations for water conservation or heat tolerance and so are often studied in comparative physiology, ecophysiology, and evolutionary physiology. One well-studied example is the specializations of mammalian kidneys shown by desert-inhabiting species. [81]
The mean chain length of an entire web is the arithmetic average of the lengths of all chains in a food web. [42] [14] In a simple predator-prey example, a deer is one step removed from the plants it eats (chain length = 1) and a wolf that eats the deer is two steps removed from the plants (chain length = 2).
A balance in these transfers is vital to the health and stability of an ecosystem. [4] Consumers balance the food chain in an ecosystem by keeping plant populations at a reasonable number. Without proper balance, an ecosystem can collapse and cause the decline of all affected species.
Ukok Plateau, one of the last remnants of the mammoth steppe [1]. The mammoth steppe, also known as steppe-tundra, was once the Earth's most extensive biome.During glacial periods in the later Pleistocene it stretched east-to-west, from the Iberian Peninsula in the west of Europe, then across Eurasia and through Beringia (the region including the far northeast of Siberia, Alaska and the now ...