DESERT & TUNDRA By Sean, Seabass, and Shamus

Desert & Tundra By Sean, Sebastian, and Shamus

Deserts

Desert soils tend to be very rich in minerals but devoid of organic material. The little rain

that does fall seeps through the sand and carries the minerals deeper into the soil in a

process called leaching. Deserts don't receive too much rain so this process is quite rare. As

a result the upper layers are rich in minerals. Deserts are incredibly dry, making it very hard

for plant species to survive there. Only a few, specialized plants grow in the desert. Desert

sand is easily blown away by wind, leaving a layer of soil called pavement. This pavement is

comprised of hard-baked sand and rock.

Desert Organism ❖ Desert organisms are adapted to survive 2 challenges:

➢ Lack of water and extreme temps.

❖ Some adaptations involve physical structures, others involve behaviors.

❖ Deserts are species-rich, complex ecosystems

Desert Plants

❖ Desert plants must be able to prevent loss of water in their tissues.

❖ Spines of cacti are adaptations which help prevent loss of water.

❖ Cacti are a native species only to American deserts.

❖ Cacti are an an example of a succulent.

Desert Animals

❖ Deserts are home to many types of animals, including: insects, reptiles, birds, and

mammals.

❖ All desert insects and reptiles have adaptations to reduce water loss.

❖ Protective covering on insects and reptiles allow them to survive dryness of a desert.

❖ Many desert animals are nocturnal, in order for them to avoid sun exposure.

Desert Climate

❏Deserts rarely get more than 25 cm of precipitation in a year

❏Most deserts receive less than 10 cm of rain a year

❏Lack of precipitation determines kinds of plants that can live in a region

❏The types of plants then determines the types of animals in the area as well

❏The lack of precipitation therefore is the limiting factor in a desert biome

❏Most of the rain in the desert falls during a few short thunderstorms

❏This is followed by long extended periods of dryness

Desert Climate

❏The desert pavement tends to be dry and compacted

❏Therefore the rain tends to run off rather than be absorbed in the ground

❏Temperatures vary greatly in the desert

❏Moisture in the atmosphere has a stabilizing effect on temperature in a region

❏Moisture acts like a blanket, absorbing heat during the day, holding warmth at night

❏Desert air contains very little moisture

❏Temperatures can rise and fall dramatically during 24 hour period

Natural Desert Formation

❏Air over the equator recieves the most direct radiation from the sun

❏This direct radiation raises temperatures and causes rapid evaporation of

water from the surface

❏This evaporation causes the air over the equator to be very moist

❏This moisture returns to Earth in frequent rainstorms

❏These rainstorms create a wet region called the tropics

❏The air then becomes dry, after letting off the rainstorms

❏This dry air eventually comes to form deserts

Natural Desert Formation ❏The exact locations of deserts within desert belts are determined in part by local

geographic features

❏Mountain ranges are one geographic feature that determines location (ex. Sierra

Nevada’s)

❏Winds from the western United States hit the Sierra Nevada’s

❏These winds force warm, moist air up and over the Nevada’s

❏As this air rises above the mountains, it cools, and lets off moisture as precipitation

❏This cool, dry air then reaches the eastern side, and picks up the moisture in the soil

❏As a result the soil becomes dry, and a desert begins to form (called rainshadow

effect )

Formation of Deserts

❖ Deserts are on every continent of Earth except Antarctica.

❖ Most deserts located on Desert Belts.

❖ Northern desert belt located on Tropic of Cancer.

❖ Southern desert belt located on Tropic of Capricorn.

Desertification

❖ Deserts are often bordered by semiarid regions.

❖ Semiarid land becomes a desert as a result of human activity.

-This process is an example of desertification.

❖ The most common example of desertification is overgrazing of animals on a small piece of

land.

Desertification cont.

❖ When overgrazing of animals occurs, the animals eat all the grasses and disrupt the soil

with their hooves.

-This causes soil to erode quickly and the land reflects more of the sun’s

heat.

❖ This process drives away rain clouds and changes weather patterns.

❖ Without topsoil and rain, the area becomes a desert.

Desertification cont.

❖ Desertification has occurred on every continent except Antarctica

-Extremely severe on every other continent.

❖ Roughly 6 million hectares of land become desert each year due to the process of

desertification.

❖ The amount of newly formed desert each year is about the same size as the state of Maine.

Tundra Climate ❏Like the desert, the tundra receives little in precipitation

❏The desert actually receives less than 25cm of rain each year

❏Main difference between deserts and tundra is temperature due to location

Located at latitudes 55° to 70° North – Alpine Tundra (high altitude)

❏In the tundra air temperature rarely is above 10 degrees celsius, even in summer

❏Because of this year round freezing, most precipitation falls as ice or snow

❏Temperature therefore is the limiting factor in the tundra

Tundra – Koziol’s addition

Location 49°41'15.71"N

54°48'9.15"W

Tundra Climate

❏ Summer days are long and cool in the tundra

❏ Because of the low temperatures, only the top layer, or active zone of soil,

thaws during the summer months

❏ The active zone can be as thin as 8 cm in some areas

❏ Beneath the active zone, is permafrost, or the soil that never thaws

❏ A dense mat of mosses, grasses covers the active zone during the summer

❏ This mat keeps the ground insulated, prevents permafrost from melting

❏ Therefore any disruption of the plants in the active zone can affect the

permafrost

Tundra Climate ❏Because of the short growing season and low temperatures, tundra vegetation does not

recover as quickly from disruption than vegetation of other biomes

❏ For example, wagons that crosses the tundra 100 years ago are still visible in some areas

❏The tundra receives a small amount of rainfall in the summer

❏Rain that falls in the summer months cannot drain through the permafrost

❏ Instead, the water collects at the surface, forming bogs, marshes, ponds

❏These areas serve as the breeding ground for insects, such as mosquitos and black flies

❏These insects are an important part of the food web of the tundra, thus showing the importance

of the permafrost in the tundra

Desert organisms

❖ Some plants grow in the tundra even though there is a very cold climate and a lack of

rainfall.

❖ The most common tundra plants are mosses, shrubs, and grasses.

❖ The summer growing season in the tundra lasts about 60 days.

Tundra Plants

The sun's radiant energy warms the ground, Tundra

plants tend to grow close to the ground in order to

capture the maximum amount of energy. Tundra plants

roots also cannot penetrate the permafrost below the

surface. Trees that grow in the tundra tend to be no

more than 1m tall. This is caused by the short growing

season and the limited space for roots to grow.

Tundra Animals ❖ Many tundra animals are

migratory, which means they are

long-distance seasonal travelers.

❖ Due to the fact that there are fewer

predators in the tundra, It is easy

and safe for animals to raise their

babies.

❖ Many migratory birds that live in

the tundra feed on the abundant

flies and mosquitoes that breed in

bogs and ponds during summer.

Tundra Animals cont.

❖ The caribou is one of the largest migratory animals in the tundra.

❖ Caribou have a thick coat of fur, which is one of the most common adaptations that tundra

animals have.

-The hairs in their fur coat trap air, which, is the best insulator on earth, to keep them

Warm in the freezing cold temps.

❖ Caribou feed on lichens, which grow on rocky surfaces.