Biome Summary
How to Read a Climograph
Every place on Earth has weather. However, different places on Earth have different types of "typical" weather. Some places are dry, some are wet, some are hot, some are cold, and some are a little of everything!
You can find out what the weather is like where you live by looking out the window or by stepping outside. Weather refers to temperature, precipitation (rain and snow), and the wind's direction and speed. Scientists who study the weather collect information from different places on Earth and come up with averages, or typical types of weather, for a particular place. This average, or typical type of weather that occurs during a year, is called the "climate."
A quick way to get an idea of the climate of a particular place is to look at a "climate-graph," or "climograph." A climograph is what scientists create to show a particular location's average temperature and precipitation during the year.
Below is a climograph for Moose Factory, Canada. To help you learn to read a climograph, the different parts of the climograph have been identified by number. A description of each of the numbered parts is given below.
1. The type of biome associated with the place.
2. The place where the temperature and precipitation were measured.
3. A scale used to indicate inches of precipitation.
4. The months of the year. The letters J, F, M, etc., stand for January, February, March, etc.
5. The temperature scale in degrees Fahrenheit.
6. A bar graph showing the average precipitation for each month. In this example, the average total precipitation is about 1 inch in January and nearly 4 inches in August. (Note: Values for this graph are found on the left-hand scale.)
7. A line graph showing monthly temperature during the year. In this example, the lowest temperature is about -5°F in January and the highest is about 45°F in July. (Note: Values for this graph are found on the right-hand scale.)Arctic Tundra
One unique characteristic of the Arctic tundra is permafrost--ground that is permanently frozen. Because the permafrost has no cracks or pores, nothing can penetrate it--neither plant roots nor water. The surface layer above the permafrost thaws each summer. This layer is called the active layer. Thickness of the active layer depends on its location in the tundra. The more northerly the location, the thinner the active layer is.
Not many kinds of animals live year-round in the Arctic tundra. Most birds and mammals only use the tundra as a summer home. Mammals that do live year-round in the tundra include the muskox, Arctic wolf, and brown bear; and each has its own way of adapting to the extreme climatic conditions. Animals need to find ways to stay warm and to provide nourishment for themselves in order to survive the long, cold, winter months.
Animal adaptations
Migration and hibernation are examples of behavioral adaptations used by animals in the Arctic tundra. The fact that many animals do not live year-round in the tundra means they leave or migrate for a length of time to warmer climates.
Hibernation is a combination of behavioral and physical adaptations. For example, during the summer the brown bear's behavior is to eat just about anything it can find; then it hibernates, or sleeps, during the winter. The bear's physical adaptation allows the food eaten during the summer to be stored as a layer of fat underneath its skin. The layer of fat insulates the bear from the cold. While in hibernation the fat is slowly converted into energy that maintains life.
A physical adaptation used by the Musk Ox is the growth of two layers of fur--one short and the other long. Air is trapped in the short layer of fur and is warmed by body heat. The warmed air, trapped close to the body, acts as insulation from the cold. The layer of long fur protects the Musk Ox from the wind and water. In addition to thick layers of fur, the Musk Ox relies on another physical adaptation to help it survive. The hooves of the Musk Ox are large and hard. During the winter months, this adaptation allows the Musk Ox to break the ice and drink the water underneath. Arctic Tundra: Plants
Plants need warmth and sunlight to grow and reproduce. In the Arctic tundra, warmth and sunlight are in short supply, even in the summer. The ground is frequently covered with snow until June, and the Sun is always low in the sky.
Only plants with shallow root systems grow in the Arctic tundra because the permafrost prevents plants from sending their roots down past the active layer of soil. The active layer of soil is free from ice for only 50 to 90 days.
Arctic plants have a very short growing season. However, in spite of the severe conditions and the short growing season, there are approximately 1,700 kinds of plants that live in the Arctic tundra. Some of the plants that live in the Arctic tundra include mosses, lichens, low-growing shrubs, and grasses--but no trees. In fact, "tundra" is a Finnish words which means "treeless".
Plant Adaptations
Deciduous Forest
The mid-latitude deciduous forest biome is located between the polar regions and the tropics. Because of its location, air masses from both the cold polar region and the warm tropical region contribute to the changes of climate in this biome. Photo © 2000-www.arttoday.com
Mid-latitude deciduous forests have both a warm and a cold season (see climograph). Precipitation ranges from 30 to 60 inches and is evenly distributed throughout the year. Much of the human population lives in this biome. Although evergreens are found in this biome, this biome is characterized by an abundance of deciduous trees.
"Deciduous" means to fall off, or shed, seasonally. Just as the name implies, these deciduous trees shed their leaves each fall. Lying on the forest floor, the leaves decay. As the leaves decompose, the nutrients contained in the leaves are absorbed by the soil. For this reason, the soils of this biome tend to be very fertile. Because this biome has fertile soil and a long, 5 to 6 month, growing season, many deciduous forests have been converted into agricultural regions.
Deciduous Forest: Animals
A wide variety of mammals, birds, insects, and reptiles can be found in a deciduous forest biome. Mammals that are commonly found in a deciduous forest include bears, raccoons, squirrels, skunks, wood mice, and, in the U.S., deer can be found in these forests. While bobcats, mountain lions, timberwolves, and coyotes are natural residents of these forests, they have nearly been eliminated by humans because of their threat to human life. Other animals that were native to this biome, such as elk and bison, have been hunted to near extinction.
Migration and hibernation are two adaptations used by the animals in this biome. While a wide variety of birds migrate, many of the mammals hibernate during the cold winter months when food is in short supply.
Another behavioral adaptation some animals have adopted is food storage. The nuts and seeds that are plentiful during the summer are gathered by squirrels, chipmunks, and some jays, and are stored in the hollows of trees for use during the winter months. Cold temperatures help prevent the decomposition of the nuts and seeds.
Deciduous Forest: Plants
Trees of this biome include both broadleaf, deciduous trees, such as maple, oak, hickory, and beech, and evergreens, such as hemlock, spruce, and fir. A deciduous forest typically has three to four, and sometimes five, layers of plant growth.
Tall deciduous trees make up the top layer of plant growth, and they create a moderately dense forest canopy. Although the canopy is moderately dense, it does allow sunlight to reach the forest floor. This sunlight allows plants in the other layers to grow. The second layer of plant growth includes saplings and species of trees that are naturally shorter in stature. A third layer (or understory) would include shrubs. Forest herbs, such as wildflowers and berries, make up a fourth layer. During the spring, before the deciduous trees leaf out, these herbs bloom and grow quickly in order to take advantage of the sunlight. A fifth layer would include mosses and lichens that grow on tree trunks.
In the spring, deciduous trees begin producing thin, broad, light-weight leaves. This type of leaf structure easily captures the sunlight needed for food production (photosynthesis). The broad leaves are great when temperatures are warm and there is plenty of sunlight. However, when temperatures are cold, the broad leaves expose too much surface area to water loss and tissue damage. To help prevent this damage from occurring, deciduous trees make internal and physical adaptations that are triggered by changes in the climate.
Desert
The defining characteristic of a desert is that it is dry. Depending on its geographical location, the annual precipitation in a desert varies from half an inch to as much as 15 inches. Rainfall is usually very localized, and although it is frequently seasonal, it is difficult to predict when or where it will occur. At times in the Atacama Desert in Chile, years have passed with no measurable rainfall at all. However, that is not generally the case. Photo © 2000-www.arttoday.com
Deserts can be either hot such as the Australian Desert or cold such as the Gobi Desert. As with all biomes, the desert climate is determined by geographic conditions. Geographic conditions such as location, high atmospheric pressure, and proximity of mountain ranges determine just what type of desert it is.
Deserts may occur along the coast such as the Atacama and Namib deserts or in the interior of continents such as the Great Basin and Australian deserts, which are far from any source of water. Coastal deserts are located on west coasts of continents between 20° to 30° latitude. Prevailing winds blow in an easterly pattern and prevent the moisture from moving onto the land. Semiarid deserts, like the Great Basin Desert, are not only located far from moisture, but are frequently associated with high mountain ranges that produce a rainshadow effect. The rainshadow effect prevents available moisture from reaching the area. The great Gobi Desert of Mongolia has little rainfall because the Himalayan Mountains prevent rainfall from moving into this region.
Because all deserts are dry, they have large daily temperature variations. Temperatures are high during the day because there is very little moisture in the air to block the Sun's rays from reaching Earth. Once the Sun goes down, the heat absorbed during the day quickly escapes back into space. High daytime temperatures and low nighttime temperatures make survival in the desert very difficult.
At first glance, deserts may appear to be without animal life. However, deserts are home to many reptiles, insects, birds, and small mammals. The kangaroo mice of North America and the bilby and red kangaroo of Australia are just a few examples of small mammals that live in the desert. Most large animals have not adapted to desert life. Their size prevents them from finding shelter from the Sun's heat and they are not able to store water for future use. Animals that do survive in the desert have developed a number of adaptations. Photo: Red Kangaroo.
The most universal behavioral adaptation used by small mammals, reptiles, and insects to deal with high temperatures is staying in the shadow (shade) of plants or rocks, thus avoiding the direct rays of the Sun. These animals also seek shelter by burrowing into the ground. Just as a basement room is cooler than an above-ground room, a burrow, even a few feet underground, can decrease the temperature by several degrees. Another behavioral adaptation used by desert animals is to remain inactive during the hot daylight hours. They hunt at night when temperatures are cool and when there is less risk of losing precious body water. Animals that use this adaptation are referred to as nocturnal. Some animals get all of the water they need from the insects, bulbs, and seeds they eat. They will not drink water even when it is available. Photos © 2000-www.arttoday.com
Some animals have developed salt glands, a physical adaptation that allows the secretion of salt without the loss of water. The absence of sweat glands, and the concentration of urine are other physical adaptations made by desert animals. Because fat intensifies heat, a unique physical adaptation of some desert animals is the storage of fat in humps or tails, rather than throughout the entire body.
No comments:
Post a Comment