Deserts(7)• Less than 10 cm’s of precipitation a year.• Most falls at one time.• Usully runs off rather than absorbed• Leaching: rainwater moving through soil• Pavement: layer of soil compacted and hard, like

cement• Two types: Cool and Hot• Cool, characterized by cold winters with snowfall and

high overall rainfall throughout the winter and occasionally over the summer

• Hot, more what we know about stereotypical deserts.

Desert organisms• adapted to low water availability• Adapted to extreme temps• Plants:• Succulents: water absorbers, thick tissues, cacti

good example• Spines/thorns modified leaves• Typically have very long roots, some up to 20 m’s

• Animals:• Nocturnal: active at night (most desert animals)• Protective shells (insects and reptiles)• Get water from the food they eat• Unique physical features, ie big ears, helps cool

animal

Forming Deserts• Geological feature play a major role• Warm air rises up the side of a mountain, cools, and

precipitates• No water is left as the air moves over and pass the

mountain…creates deserts.• Desertification: the formation of deserts (approx. 6

million hectares a year become deserts)

Tundra biome(7)

• Cold, windy, and dry region. Northern hemisphere• One of the largest biomes• Less than 25 cm rain a year• Permafrost: permanently frozen soil, just below the

surface.• Least resilient of all biomes

• Plants• Small, grow close to ground, and shallow roots• All are dwarfed due to shallow roots, and high winds.

• Animals• Most migrate (move from area to area)• Thick coats, hairs filled with air (acts like insulation)• Wide feet, hooves, etc

Grass Lands Biome(8)• More water than deserts but not enough to support a

forest.• Usually border deserts.• dominate species….grass• Fires are common• Benefits of fire• Burn off dead matter• Kill competing species• Keep tree numbers low• Aids in germination

• Usually rich in nutrients (soil)• Typically have a “rainy” and “drought” season• Three basic categories grasslands are divided into.

• Steppes and Prairies• Short grasses, 25cm to 50 cm of rain per year• Prairies: rolling hills and plains.• We call them prairies, Russians call them steppes,

Asia call them veldt, Argentina calls them pampas.• What ever the name, we get most our food from these

areas due to the high fertility of the soil.• Sod forming grasses: form a mat of soil and roots• Humus: layer of organic matter formed by dead roots• Bunchgrasses: short fine bladed grasses that grow in a

clump• Dust bowl: what happens when over farming destroys

the ecosystem, and the roots can no longer mat the soil, and wind blows the dry sand around.

Savannas (8)

• Tropical or subtropical grasslands with typically less than 150 cm per year of rain.

• Very distinct rainy season, and drought. Most of the rain falls within a couple or months

Organisms• Must be resistant to drought and fires• Many plants grow “runners” long horizontal stems both

above and below the ground• Plants typically grow very rapidly• Animals are typically concentrated in smaller areas (water

sources)• Vertical feeding pattern: different animals eat vegetation

at different heights.

Coniferous Forest (9)• Upper US and Canada• Warm summers, long cold and dry winters• Rain in summer, snow in winter• 40-200 cm’s of precipitation per year• Coniferous means “cone bearing” • The trees are also called conifers, produce seed bearing

cones.• Leaves are needles, long, thin, and very waxy. They do not

loose there leaves once a year, but rather continuously all year.

• Soil is poor and acidic, due to the needles

• All organisms have to bee adapted to the long, cold winters• Trees, due to leaf shaped, don’t trap snow• Animals have think hides/hair and typically eat

seeds, plants, or even bark.• Many migrate (larger ones) or live under the snow

and some hibernate.

Home Work:Read page 141, respond to questions 1 and 2.

Deciduous Forest(9)• Where we live!!• Deciduous: sheds leaves during a part of the year• Four well defined seasons (mostly)• Temps as high as 30 c and as low as -30 c.• 50 to 300 cm’s of precipitation per year• Three distinctive vegetation layers• Canopy top most, receives most of the sun light (more

prevalent in rain forests though)• Understory, small trees and shrubs• Forest floor, very nutrient rich. Humus: decaying

leaves, deep rich layer of soil.• All has been changed drastically by human activityHomework. Read pg 145 answer 1 and 2.

Rain Forest(9)• Found near the equator• Average 25 c all year long• 200-450 cm’s of rain per year• Distinctive canopy, vertical ecosystems.• May contain 70% of all terrestrial species• Cover 6% of the earths surface, holds 50% of the

earths biomass.• Extremely diverse: one scientist found 43

different species of ants, on one tree.• Very poor soil (low nutrients)

Vertical ecosystems: ecosystems found at different levels above the ground, supported solely by the organisms they are living on.

• Deforestation: the destruction of forest as a result of human activity• Once TRF covered 10% of the earth, now

down to only 6%.• Most found in developing countries who

need the money• Slash and burn techniques often used• When a tree in the TRF is cut down, you

don’t just lose the tree, but the entire vertical ecosystem, which could consist of several species.