UWC Grade 5 (2009-2010)

Human impact in desert areas 1700,2000 and 2050

NTERDEPENDENCE - In all environments, various plants and animals depend on each other either directly or indirectly for survival.

Desert biomes can be classified according to several characteristics. There are four major types of deserts: Hot and dry Semiarid Coastal Cold

Deserts cover about one fifth of the Earth's surface and occur where rainfall is less than 50 cm/year.

The animals include small nocturnal (active at night) carnivores. The dominant animals are burrowers and kangaroo rats. There are also insects, arachnids, reptiles and birds. The animals stay inactive in protected hideaways during the hot day and come out to forage at dusk, dawn or at night, when the desert is cooler.

Desert plants have developed various ways to get as much water as possible and to reduce water loss.Some plants have long roots to get water deep in the soil, or branched roots to get water over a wide area. With thick waxy layer on the stems and leaves, water can be retained and the tissues are protected from strong sunshine. Some plants have pin-like leaves to reduce water loss.        Barrel Cactus             Many desert plants are succulents and they store water in their swollen stems or leaves.  

World Rainforest Movement

Sahara Desert Plants The Sahara Desert is often described as a bleak and barren plain. In truth, it is very beautiful and full of different Sahara Desert plants. Sahara Desert Plants Among desert areas throughout the Earth, there are two types. The cold type of desert, which is often found in Arctic regions, is an area that gets very little precipitation. The cold desert can be covered in snow, however, and the temperatures here are chilly and unsuitable for sustaining many life forms. The other type of desert is known as the hot desert, and this is what people usually think of when they picture a desert area. This type of desert is extremely warm and dry, with temperatures reaching unbearable levels, and little to no rain to sustain those who live here. The biggest of the hot deserts is the Sahara Desert, located in Africa. Although this desert is not the most hospitable place for organisms to take up residence, the Sahara Desert plants defy the odds and thrive here.

These ecosystems are either barren or with scanty vegetation consisting of mainly thorny bushes. Deserts are classified as warm (hot) and cold (temperate) deserts. The hot deserts are the Sahara in Northern Africa, Kalahari in Southern Africa, Thar in India, Atacama in South America, deserts of Mexico and Australia.The deserts of Iran and Turkey, Gobi desert of Mongolia, some deserts of Argentina are recognised as temperate or cold deserts. Characteristics of Desertsi) Most deserts receive some rain every year but not uniform. ii) Light green covering of annuals is seen just after rains.iii) Have scanty vegetation, clear skies, hot days and extremely cold nights. iv) Soil is rocky and encrusted with sand or salt.v) Long periods without precipitation and extreme temperature (50 - 60oC) conditions (arid lands) impose considerable restraints on the flora and fauna which inhabit there. vi) Sandy storms are very frequent.vii) Occur generally in rain shadow areas. Flora1) Includes succulents such as Cacti and Euphorbias, which can store water in their tissues. 2) Trees with long spreading roots such as Acacia, Prosopis, Phoenix (dates) are found.3) Ephemerals (short lived) such as Boerhaavia repens are seen only during rainy season. FaunaMost desert animals are nocturnal and avoid the heat of the day by burrowing into the cooler soil. Animals include ants, locusts, lizards, Gila monster, coral snake, rattle snake, burrowing owls, Gambel's quail, kangaroo rats, rabbits, camel, skunk, badger foxes, jackals and desert cats. In general, the organisms having specialised structural and physiological and behavioural adaptations to withstand the extreme temperatures only can survive in a desert.

A Food Pyramid in the Hot Desert Biome      Here we see a food pyramid that shows how the Kilocalories pass up the food chain.      The first trophic level is occupied by the primary producers, which are the plants.  Plants make food through photosynthesis. The limiting factor for these plants is the shortage of water, so they produce fewer than 200 Kilocalories of food for the animals for each square meter each year.     The primary consumers, who eat the plants, occupy the second trophic level. These animals have very little to eat, and are small. Many are insects, or reptiles, who are cold blooded and who use less energy to maintain their bodies than mammals and birds do. As food for predators, they provide about 20 Kilocalories per square meter per year for predators.      The predators are the secondary consumers. They occupy the third trophic level. Again we see cold-blooded animals, such as snakes, insect-eating lizards, and tarantualas. Only about 2 Kilocalories per square meter per year are stored in their bodies. In the harsher desert environments, they are the top predators.     In areas where deserts get more rain, more plant material is produced and a few tertiary consumers may be able to survive. They form a fourth trophic level.      This diagram shows the energy available at each trophic level in the hot desert biome. These numbers tell about the numbers of Kilocalories per square meter per year.  Cold Desert Energy Pyramid  Introduction to Desert Biomes  Return to Introduction to Biomes © Elizabeth Anne Viau, 1999. This material may be used freely for instructional purposes but not sold for a price beyond the cost of reproduction. Please inform the author if you use it at eviau@earthlink.net

The Amazon Rainforest By Alec The Amazon rainforest has many different plants that can be used as herbal medicines. Some of the most important medicines come from the Amazon. They have been used for hundreds and hundreds of years. These plants can be deadly if taken in large doses, but in small doses they can be very helpful. They can be used to cure headaches, skin irritation, high blood pressures, and many other diseases. Here are some of them. White Trillium The white trillium has three petals, three sepals, and three leaves. If the leaves are chewed, it can help cure snake bites. If the plant’s petals are chewed, they can help ease childbirth, and the sepals if chewed are used to help cure fevers. Cinchona Tree (Cinchona officinalis) The bark of this tree is used to make Quinine, a medicine that helps treat Malaria, a serious disease. A number of various other chemicals can also be made from Cinchona, and these chemicals include cinchonine, cinchonidine and quinidine. However, quinine has been replaced by other drugs such as chloroquine and mefloquine, and now quinine is rarely used to treat malaria. Foxglove (Digitalis purpurea) The leaves of this plant contain digitalis, a substance used to treat heart problems. When taken in large doses it can produce palpitations and dizziness, but when taken in smaller doses it can help the heart beat more slowly. This medicine had many effects, and sometimes it cured in miraculous ways, but it mostly produced violent reactions, occasionally killing because it was taken in very large doses. The foxglove tea is used as a morning tea to aid in birth control. Opium Poppy (Papaver somniferum) The opium poppy is used to make Morphine and Codeine, two drugs that are used as painkillers. The opium gum may be crudely refined and smoked, or converted to morphine and heroin.

AMAZON QUICK FACTS obtained from a variety of sources, simply organized, none verified and not meant to be the definitive guide to Amazon facts. The Amazon is the largest and densest rainforest on earth The Amazon covers 2.5 million miles, about the size of the USA west of the Mississippi If Amazonas were a country, it would be the 9th largest on earth Each minute the Amazon River discharges 3.4 million gallons of water into the Atlantic, 14 times the discharge of the Mississippi The Amazon runs 4007 miles from its origin in the Andes to the Atlantic, making it the second longest river on earth During its journey it touches and-or travels through 8 countries There are 200 major tributaries of which 17 are more than 1000 miles long and 10 of which discharge more water than the Mississippi Its vegetation represents about 1/3 of the remaining forest on earth and provides about 15% of the world's new oxygen Scientists have catalogued: 2500 species of fish 1500 species of birds 1800 species of butterflys 4 types of big cats 200 species of mosquitos 50,000 species of higher plants

What is a Biome?     A biome is a large area with similar flora, fauna, and microorganisms.  Most of us are familiar with the tropical rainforests, tundra in the arctic regions, and the evergreen trees in the coniferous forests. Each of these large communities contain species that are adapted to its varying conditions of water, heat, and soil.  For instance, polar bears thrive in the arctic while cactus plants have a thick skin to help preserve water in the hot desert.  To learn more about each of the major biomes, click on the appropriate heading to the right.  What is an Ecosystem?     Most of us are confused when it comes to the words ecosystem and biome.  What's the difference?  There is a slight difference between the two words.  An ecosystem is much smaller than a biome.  Conversely, a biome can be thought of many similar ecosystems throughout the world grouped together.  An ecosystem can be as large as the Sahara Desert, or as small as a puddle or vernal pool.     Ecosystems are dynamic interactions between plants, animals, and microorganisms and their environment working together as a functional unit.  Ecosystems will fail if they do not remain in balance.  No community can carry more organisms than its food, water, and shelter can accomodate.  Food and territory are often balanced by natural phenomena such as fire, disease, and the number of predators.  Each organism has its own niche, or role, to play.

Mojave National PreserveWorld Deserts World Deserts North American Deserts Protecting Deserts Home Desert lands cover incredible distances. Many who have driven through deserts in the United States may think they are enormous, but they are only the fifth largest in the world covering about 500,000 square miles. By contrast the great Sahara Desert covers almost 3.5 million square miles, the Australian deserts 1.3 million square miles, the Arabian deserts 1 million square miles, while the deserts of Turkestan have 750,000 square miles. Numerous smaller deserts are also scattered across the globe. All are unique, and have adapted to their own particular environments. Global Weather PatternsDeserts tend to occur in two belts that circle the globe. Both the Northern and Southern Hemisphere have this belt located between 15 and 35 degrees latitude, roughly centered over the Tropic of Cancer and the Tropic of Capricorn. This is no accident. The sun is more directly overhead the equatorial region so it receives the most intense sunlight, and this solar energy heats the air. Hot air has two important qualities: it can hold enormous quantities of moisture, and it rises up into the atmosphere. So hot tropical air tends to be moist and rise into the atmosphere. As this air rises it cools, condensing the moisture and converting it to water where it falls as rain. This is why rain forests tend to occur near the equator. What goes up must come down, and gravity pulls this mass of rising air back to the ground. Tropical air typically falls at about 30 degrees latitude on either side of the equator and along the desert belt, but robbed of its moisture it is now hot and dry. The result are often persistent high pressure systems that tend to block incoming storms, or push them into other regions. These patterns make deserts possible, but typically other factor must also intrude to make deserts a reality.

Deserts take up about one third (33 percent) of the Earth's land surface.

Deserts are often composed of sand and rocky surfaces.

In hot deserts the temperature in the daytime can reach 45 °C/113 °F or higher in the summer, and dip to 0 °C/32°F or lower in the winter.

Animals Armadillo Lizard Banded Gila Monster Bobcat Cactus Wren Coyote Desert Bighorn Sheep Desert Kangaroo Rat Desert Tortoise Javelina Cactus Ferruginoug Pygmy Owl Sonoran Desert Toad Sonoran Pronghorn Antelope Thorny Devil Climate Return to Desert

The smallest rhinos are found in the tropical rainforests on the islands of Sumatra, Java and Borneo.  These two species are very rare and extremely difficult to find.  Only a few photographs of them in the wild have been taken.

Sumatran and Javan rhinos—use their speed to disappear to safety in the thick grass or jungle.

For the rarest rhinos, the Sumatran and Javan rhinos, their survival may depend on how well we learn to breed them in captivity while we work to protect their wild tropical rainforest home from destruction.