Resources of Afghanistan

Deserts

The desert covers one-fifth of the earth's surface. It is defined as a region that receives less than 50 cm of rain annually. The desert biome is found along the western regions of North and South America, and Asia, the northern part of Africa, and the central areas in Australia. There are few large animals found in deserts because most animals are not able to withstand the heat, and store enough water to keep their bodies hydrated. The main type of animals found are invertebrates, such as reptiles.
http://www.blueplanetbiomes.org/desert.htm


General properties of deserts(adapted from http://www.blueplanetbiomes.org/desert.htm)

A. Climate: Why are deserts so incredibly hot?
http://library.thinkquest.org/
Deserts were originally lands that contained water. Scientists believe that small changes in temperature caused the once fertile land to change- plant deaths and soil erosion led to the formation of an arid land called the desert. Water and wind play important roles in shaping the desert. When heavy rain floods the desert, rocks and soil are moved around the area. Powerful winds create sandstorms and dust storms. They are responsible for the destruction of some of the caves, cliffs, and arcs found in deserts.

The common characteristic among different types of deserts is that all deserts are arid places. However, not all deserts are "hot." Some deserts can be cold for most of the year. The Gobi desert and the Great Basin desert are examples of cold deserts. At night, temperature can drop to below freezing in some deserts. Hot deserts are nearly always above 67 degrees Fahrenheit.

B. Plant adaptation
Plants found in deserts are adapted to their environment. Plants learn to efficiently store water and moisture. The cacti and saguaro are important desert plants. Plants are slow to grow to conserve moisture. Many plants shed their leaves during dry temperature to conserve water and moisture. This contributes to the slow growth rate of plants. However, slowing down growth is beneficial for desert plants because plants use less energy, food, and water during the hot season. Other plants have special types of leaves that allows them to prevent moisture from evaporation. Some plants excrete special chemicals (like a waxy resin) in their leaves.

Some examples of desert plants are the cactus, the Creosote Bush, and the Desert Ironwood.

C. Animals
Animals residing in the desert are also well adapted to their environment. They regulate their body according to temperature shifts. The body heat of mammals remain relatively constant as long as they do not stay in the heat for too long. Amphibians and reptiles' body temperature reflect the temperature of the desert. Burrows are a way to escape from the scathing heat of the desert. During the hottest seasons, some animals estivate. Estivation is similar to hibernation but desert animals estivate to escape the heat.

D. There are four classifications for deserts: Dry deserts, Semiarid deserts, Coastal deserts, or cold deserts. http://www.ucmp.berkeley.edu/glossary/gloss5/biome/deserts.html

E. Deserts in Afghanistan
http://www.worldwildlife.org/wildworld/profiles/terrestrial/pa/pa1313_full.html
There are desert basins in parts of Afghanistan. The Central Persian Desert covers central Iran, and a small part of north Afghanistan. The worldwildlife website notes that "the area's vegetation ranges from sagebrush to saltland and psammophytic plants and includes chernopodiaceous communities in Afghanistan." The plateau covers 1,648,000 kilometers squared (most of desert in Iran). This area can be divided into two parts. One part, the Dasht-e-Kavir, is a "salty" desert. The other part, Dasht-e-Lut, is characterized by sand and gravel.

F. Other deserts also present below: (http://en.wikipedia.org/wiki/Deserts_and_xeric_shrublands)

desert1.jpg
desert2.jpg

Images from: http://www.nationalgeographic.com/.../ pa/pa1326.html ; http://minyos.its.rmit.edu.au/~dwa/AfghanDesert1.html

Copyright©2006 Michelle Huynh, Ian Linford, Kyle Gee
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