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Transcript of Desert Biome
of ecosystem. Depending on its geographical location, the annual precipitation in a desert varies from
half an inch to as much as 15 inches. Physical Features: Abiotic Factors Physiographic Factors: The Sahara Desert covers most of northern africa, its
approximately 35 degrees N to 15 degrees N. Its longitude
extends from about 35 degrees W to 15 degrees E
Every year there are about
60,000 to 80,000 wildfires per
year in the dry desert. Dried
native flowers are major
contributors to why fires
carry so quickly, and vastly,
though their partner in crime
are huge gusts of wind the carry the flame and allow it to spread and cover more ground. http://www.marietta.edu/~biol/biomes/images/grassland/whittaker_grassland.jpg http://www.marietta.edu/~biol/biomes/images/desert/whittaker_desert.jpg http://www.marietta.edu/~biol/biomes/images/woodland/whittaker_v2.jpg Climate: The desert's climate is very hot and dry. Weather is not the same in all deserts. Coastal deserts are in moderately cool to warm areas. They usually have cool winters followed by fairly long, warm summers. The temperature in the winters is generally 41°F (5°C) or below. In the summer, the weather heats up to between 55° and 75°F (12 and 24°C). Deserts are usually located in areas near the equator. Most are just barren land with sand that stretches for miles.
There is a shortage of precipitation in the desert receiving less than 25 centimeters a year, receiving the least rain in the spring & summer. Although August is one of the months that receives the most rain with up to 1.3 centimeters of rain. The months of December to March is the time period when the desert receives the most precipitation. In May and June it does not receive any precipitation at all.
Because of the lack of precipitation and the extreme weathers, the growing season is limited by the brief period of rain, which in some cases, do not occur in years.
Wind dehydrates soils and living things. Sand and dust particles are moved by desert winds. Desert winds also remove organic debris that makes the soil fertile. Since there are little amounts of plants in deserts, wind erosion occurs more easily. The Soil
Deserts primarily consist of
wind-deposited sand which originated
from sandstone that eroded over time.
Wind force and various wind directions
transport and deposit sand and in the
process create different types of dunes. Though the soil in the desert are low in organic matter, and are basically biologically inactive you can find nitrogen-fixing bacteria. In areas with higher concentrations of organic matter expanding-lattice clays are common. Hot Desert The temperature range for the subtropical desert above goes too far to the right. Which indicates that the average temperature can drop to almost -10 degrees. The temperate grassland and desert biomes outlined in the graph above are not separated; the desert part of this would be the drier part. Finally, if one inserts the woodland biome into the figure, as many ecologists do (bottom figure), the temperate grassland and desert are displaced to the colder range of the subtropical desert range. Biotic Factors Animals of the Hot Deserts: Barrel Cactus Brittlebush Chainfruit Cholla Crimson Hedgehog Cactus Triangle-Leaf Bursage Desert Plants: Plants in the desert are adapted to the dry conditions. Some plants are annuals. Their seeds wait in the ground for years until there is a rainy winter: then they sprout rapidly and grow as fast as they can. They race the sun to make seeds before the water evaporates and the heat dries them up. Some of these plants are so tiny that the whole plant could be hidden under a dime. Others spread colorful blossoms over the sand and rocks for a few brief days. Some plants develop water-storing strategies. Cacti have chlorophyll in their fleshy stems, and they store the water that they gather in those stems. They defend themselves with sharp spines. They have large networks of roots that lie under the ground near the surface of the soil. If it does happen to rain, these roots can soak up the water quickly. Here are a
of Desert Plants:
The desert is a hard place to see animals. High temperatures during the day are particularly tough on large mammals. But just like desert plants, desert animals also make special adaptations. Smaller organisms can seek out the shade of small desert plants, or burrow underground. These animals do not need as much food as warm-blooded animals, and can go weeks between meals if they have to. The sun provides heat for them, and they can find little niches in the rocks to hide in during the heat of the day and during the cold nights. Here are some examples: Zebratail Lizard - Callisaurus draconides Bactrian Camel, Camelus bactrianus black-tailed jackrabbit - Lepus californicus Rock hyrax (Procavia capensis) Here are some characteristics of animals for better adaptation in their environment: A nocturnal lifestyle, which keeps them out of the heat of day (and out of human sight as well). Living in burrows, which are cooler and more humid. This often goes along with #1, the burrow becomes a place to sleep during the hot day. Slender bodies with long limbs - these are better for shedding heat. Adaptations for reducing water loss - specialized snouts, waxy body coatings, efficient kidneys, etc. are all part of this strategy. Eyes protected from the sun. Long eyelashes or deep-set eyes not only reduce harsh sunlight but reduce evaporation from the eyes. Cold Desert The desert may appear to look like heaps of dry sand, but it has a constantly changing topography, from rocky stream beds to powdery piles of sand.
Ergs: It’s crazy to think that in the middle of the desert you can find many seas; well, sand seas. Ergs are the Saharan dunes featured in many Indiana jones movies. They cover about 20% of the Sahara and can stretch for miles.
Regs: Making up 70% of the Sahara are long plains of black, white and even red sand and gravel. The Libyan reg stretches for 340,000 square miles. Like the seas and rivers that used to flow through, plant life is sparse while animal life in limited to rodents.
Hamadas: The Hamadas are huge stones and rocks that can soar over 11,000 feet. They include the Atlas mountains
Wadis: A wadis is a temporary source that is located mainly on the mountains and is fed by rainfall, most of the Sahara’s plant life resides there.
Chotts: Chotts are huge dry valleys that fill with salt once it rains. Large chotts are often found throughout the desert. A fun fact is that key scenes from “Star Wars” were filmed in a large chott in western Tunisia called Chott el Djerid.
Oasis: An Oasis is a natural spring, an artesian well or entire irrigation systems that can support a tiny village or an entire farm. They can vary in size from about 2.5 acres or 800 square miles. About 75% of the deserts animal and plant life live in the oasis. Topography: On earth we have some cold deserts, where year round cold and unmelting snow create environments where life forms face formidable challenges. When the weather is so cold that snow never melts, the annual rainfall (snowfall) is not an important factor for life forms. Although scientists have found some bacteria living underneath glaciers, life forms in this environment are generally just visitors. The growing season lasts a mere six to eight weeks Human Impact: Climate: They have short, moist, and moderately warm summers with fairly long, cold winters. The mean winter temperature is between -2 to 4 C and the mean summer temperature is between 21-26 C.
During the winter season It is not out of the ordinary to get large amounts of snow. The mean annual
precipitation ranges from 15-26 cm.
Annual precipitation has reached a
maximum of 46 cm and a minimum of
9 cm. Humans have harmed the earth in many ways, in this section, we will be talking about the harms humans have caused in hot and cold deserts. In Egypt, you can travel throughout the city and notice the large piles of garbage that fill the ditches and cover the landscape. Though officials say it’s a work in process and that they are trying to get the waste problem under control, within the last 5 years the problem has only gotten worse. As well as garbage filling the streets you can find numerous fume dunes throughout the desert. A fume is a dune where people will gather garbage
and burn it off leaving masses of black charcoal coating
the sand in these areas. Though it may seem like the negative
impacts humans have had on the dessert, us humans have had a
few positive impacts. As silly as it seems a popular form of
transport is Donkeys, throughout cities seeing someone ride a
donkey is as popular as someone driving a car. That cuts down on
the carbon dioxide emissions we release into our atmosphere. The soil is heavy, silty, and salty. It contains alluvial fans where soil is relatively porous and drainage is good so that most of the salt has been leached out. Antarctic is the fifth largest continent of the world at 14 million square kilometres and is covered by a permanent continental ice sheet. The ice is distributed in two major ice sheets, the East Antarctic and the West Antarctic, and in addition there are shelf ice, extending over the sea water. Antarctic inland ice ranges in thickness up to 5000 m, with an average thickness of about 2400 m, making Antarctica by far the highest of the continents. Straddling the South Pole, Antarctica is cold even during summer. Much of the continent is a cold desert with very low precipitation rates. Topography: Animals of the Cold Desert: Despite the harsh conditions, there are animals that thrive in cold desert biomes. Here are some examples: Arctic Fox Kangaroo Rat Blue Whale Penguins In the cold desert, like Antarctica due to global warming the iceburgs are melting as well as the permafrost, due to this sea levels are rising. Although there are many factors on why the polar bear population is decreasing, one of the main factors is the melting of ice burgs because the ice burgs are melting at a rapid rate it's depriving the polar bears of their natural habitat and making it harder for them to find food. The rain will freeze but usually does not come down as snow, mostly rain. The continent of Antarctica is positioned in 90º 00' S latitude and 0º 00' E longitude respectively.
It is located on the southern part of the Antarctic Circle. The total area is slightly smaller than 1°5 times to that of USA. It is the fifth largest continent with a total area of 14 million square kilometers. The coastline stretches for 17,968 kilometers. Altitude and Longitude http://www.grida.no/graphicslib/detail/antarctica-topography-and-bathymetry-topographic-map_144e
http://library.thinkquest.org/26442/html/life/plant.html Bibliography: Lichen Plants of the Cold Desert: The extreme conditions make Antarctica a habitat in which only the hardiest can survive. Very few species have been recorded on the 2% of the continent that is ice-free. They include about 150 lichens, 30 mosses, some fungi and one liverwort. Moss Algae