Best Results From Wikipedia Yahoo Answers Youtube
Arctic ecology is the scientific study of the relationships between biotic and abiotic factors in the arctic, the region north of the Arctic Circle (66 33â€™). This is a region characterized by stressful conditions as a result of extreme cold, low precipitation, a limited growing season (50â€“90 days) and virtually no sunlight throughout the winter. The Arctic consists of taiga (or boreal forest) and tundrabiomes, which also dominate very high elevations, even in the tropics. Sensitive ecosystems exist throughout the Arctic region, which are being impacted dramatically by global warming.
To understand Arctic ecology, it is important to consider both the terrestrial and oceanic aspects of the region. A few important parts of this environment are sea ice and permafrost.
Sea ice is frozen seawater that moves with oceanic currents; it provides important habitat and a resting place for animals, particularly during the winter months. Over time, small pockets of salty seawater get trapped in the ice, and the salt is squeezed out. This causes the ice to become progressively less salty. Sea ice persists throughout the year, but there is less ice available during summer months.
Large portions of the land are also frozen during the year. Permafrost is substrate that has been frozen for a minimum of 2 years. There are two types of permafrost: discontinuous and continuous. Discontinuous permafrost is found in areas where the mean annual air temperature is only slightly below freezing (0|Â°C|Â°F|0|abbr=on|lk=on|disp=s); this forms in sheltered locations. In areas where the mean annual soil surface temperature is below -5|Â°C|Â°F|0|abbr=on|lk=off, continuous permafrost forms. This is not limited to sheltered areas and ranges from a few inches below the surface to over 300|m|ft|-2|abbr=on|lk=off deep. The top layer is called the active layer. It thaws in the summer and is critical to plant life.
Moisture and temperature are major physical drivers of natural ecosystems. The more arid and colder conditions found at higher northern latitudes (and high elevations elsewhere) support tundra and boreal forests. The water in this region is generally frozen and evaporation rates are very low. Species diversity, nutrient availability, precipitation, and average temperatures increase as you move from the tundra to boreal forests and then to deciduoustemperate ecosystems, which are found south of these Arctic biomes.
Tundra is found from 55 Â° to 80Â° N latitude in North America, Eurasia and Greenland. It can be found at lower latitudes at high elevations as well. The average temperature is -34|Â°C|Â°F|0|abbr=on|lk=off; during the summer it is less than 10|Â°C|Â°F|abbr=on|lk=off. Average precipitation ranges from 10|to|50|cm|in|0|abbr=on|lk=off, and the permafrost is 400|-|600|m|ft|-2|abbr=on|lk=off thick. Plant species supported by tundra have small leaves, are short (74 mm to <5 m), tend to be deciduous, have a high ratio of roots to shoots, and are composed mainly of perennial forbs, dwarf shrubs, grasses, lichens, and mosses.
In comparison to tundra, boreal forest has a longer and warmer growing season and supports larger species diversity, an increase in canopy height, vegetation density, and biomass. Boreal conditions can be found across northern North America and Eurasia. The boreal forests in the interior of the continents grow on top of permafrost due to very cold winters (see drunken trees), while much of the boreal forest has patchy permafrost or lack permafrost completely. The short (3â€“4 month) growing season in boreal forests is sustained by greater levels of rainfall (between 30|and|85|cm|in|abbr=on|lk=off|disp=s per year) than the tundra receives; This biome is dominated by closed canopy forests of evergreen conifers, especially spruces, fir, pine and tamarack with some diffuse-porous hardwoods. Shrubs, herbs, ferns, mosses, and lichens are also important species. Stand-replacing crown fires are very important to this biome, occurring as frequently as every 50â€“100 years in some parts.
Adaptations to conditions
Humans living in the Arctic region generally rely on warm clothing and buildings to protect them from the elements. Acclimatization, or the adjustment to new conditions, appears to be the most common form of adaptation to cold environments. No genetic advantage has been found when different people groups or races are compared. There is no evidence that fat is grown in response to cold, although its presence is advantageous. Amazingly, most people living in the Arctic region live a lifestyle very connected to the environment, spending significant time outside and depending heavily on hunting and fishing.
Animals that are active in the winter have adaptations for surviving the intense cold. A common example is the presence of strikingly large feet in proportion to body weight. These act like snowshoes, and can be found on animals like the snowshoe hare and caribou. Many of the animals in the Arctic are larger than their temperate counterparts (Bergmannâ€™s rule), taking advantage of the smaller ratio of surface area to volume that comes with increasing size. This increases the ability to conserve heat. Layers of fat, plumage, and fur are also very effective insulators to help retain warmth and are common in Arctic animals including polar bears and marine mammals. Some animals also have digestive adaptations to improve their ability to digest woody plants either with or without the aid of microbial organisms. This is highly advantageous during the winter months when most soft vegetation is beneath the snow pack.
Not all Arctic animals directly face the rigors of winter. Many migrate to
1 History of the theory; 2 Types of succession. 2.1 Primary and secondary succession; 2.2 Seasonal and cyclic succession; 2.3 Causes of plant succession ...
From Yahoo Answers
Answers:Yes stress effects your body in many ways many times women will not complete their cycles (aka get their monthly) when they are stressed, it happens to me if I get overly stressed, but it also does a number on your body.
Answers:That's ridiculous, actually. There are animo acids that are found in larger quantities in meat than vegetarian sources (I believe that's what they meant, based on your use of "enzyme" and "protein"), but you can get all of the essential amino acids from plant-based foods. Some people are convinced that you can't, or that you have to carefully combine them at each meal, but science is on our side. Tryptophan, which your brain uses to process seretonin and other nice happy-feeling neurotransmitters, is actually more plentiful (by weight) in some vegetarian foods than it is in meat foods. Just look up amino acids and their functions to see what does what. Then look up dietary sources and you'll see that you can easily get them without eating meat.
Answers:Acid rain has a pH below (B) The reusing of resources is called (B) Which of the following is not a natural resource? (D) The greenhouse effect is caused by large amounts of _____ in the air. (B) Which of the following is not a fossil fuel? (C) Smog is a combination of (A) Many lakes in Minnesota and New York are dead because of (Not sure). _____ quickly brings about soil erosion when bare soil dries out. (C) When children eat old paint, they can become sick from the _____ in the paint. (B) Burning coal produces acid rain because coal contains (B) A toxic waste produced in making paint and ink is (not sure) A gas in polluted air that can harm humans is (C) Smog if a form of (A) Sulfur dioxide is a form of (B) Burning coal to produce energy is a form of (A) _____ may make fish harmful for humans to eat. (C) Heavy metals are a form of (B) Soot is a form of (A) _____ may irritate the eyes, nose, lungs, and throat. (A) Plastic waste is a form of (B) Gasoline engines cause (A) PCB is a form of (C) Mercury is a form of (not sure) Dump sites are a form of (B) Pesticides result in (C) Untreated sewage is a form of (C) Fertilizer can cause (C) Coal dust results in (A) An endangered species _____ become(s) extinct. (B) Car engines produce _____ pollutant gases. (B) In a refuge, an animal is _____. (A) If snow has a pH of 4.5, it is an _____. (A)
Answers:acid rain has 'killed' all the high elevation lakes in the Anarondaks. A tour guide pointed out that it is not natural for lakes to be so clear, it indicates there is no microscopic life in the lake. This is the case with lots of mountain lakes (how sad). Acid rain is not the cause of global warming or depletion of the ozone layer, it's simply another sad result of using fossil fuels.