1. Biomes

2. Factors determining the distribution of major life-zones
Differential heating of the Earth’s surface by the sun
The shape of the Earth
Tilted axis and rotation of the Earth (seasonality)
Distribution of water and land and the differences in their physical properties

3. Belts of different biomes parallel with the Equator
Water movement disrupt this pattern

7. Tundra Between taiga and permanently frozen polar regions.
Annual precipitation less than 250mm.
Water not available all the time
Summer: soil thaws, but half a meter down it remains frozen: permafrost
No trees, bogs ponds and herbaceous plants.
Woody plants (few) are dwarfs.

10. Taiga Coniferous forest Short cool summers Long dry cold winters
Precipitation is mm annually in the form of snow.
Stream and rivers.
Firs, spruces, birches.
Soil: shallow hummus layer poor in nutrients and acidic.

12. Grasslands Between forest and desert biomes.
mm rainfall during mostly summer months
Winter cold and dry.
Huge amount of hummus (over 1 meter thick)
America: Prairie; Eurasia: Steppe; South America: Pampa
Large number of herbivores live there

14. Deserts Less than 250mm annual precipitation.
Precipitation is unpredictable with long periods of drought
Mild winters in warm deserts (Sahara) with few freezing days
Cold winters with extended periods below freezing (Gobi desert) in cold deserts.
Sparse plant cover
A lot of reptiles and rodents. Most animals are nocturnal.
Soil very poor in nutrients.

17. Savanna Biome between desert and tropical forest
mm rain with a wet season and a dry season.
Temperature high all year long.
Tree are drought tolerant (baobab, acacia)
Soils are poor because thy are washed out during rainy season.
Trees widely spaced, various species of grasses.
Plant species is fire tolerant.

19. Rain forest Close to Equator. Temperature very even all year long.
Annual rainfall is mm (up to 17 feet) per year.
Humidity is very high
Excess rainfall and rapid decomposition the soils are devoid of nutrients.
Organic matter is in the form of decaying animals and organisms
Many layers of canopy that support a lot of wild life

21. Aquatic Biomes (www.mbgnet.mobot.org)
Largest part of the biosphere (75% covering the Earth surface). The most important biomes are there.
Freshwater regions: low salt concentration (<1%)
Ponds and lakes
Streams and rivers
Wetlands (marshes, swamps and bogs)
Marine regions: ¾ of Earth’s surface
Oceans (tropical and temperate)
Coral reefs
Estuaries.
Shorelines.

22. Temperate Deciduous Forest
Eastern North America and Europe
Summers hot and humid, winters are cold
Rainfall is between 750mm and 1500 mm per year
Oak, maple, hickory, beech, chestnut, birch, fern, mosses and grasses.
Foxes, wolves, deer, raccoons, squirrels.

23. Maintenance and change in ecosystems.
Rules for maintenance:
Constant energy (sun)
Presence of producers
Cycle of materials
Changes in ecosystems:
Some organisms are replaced by other kinds: ecological succession
Stable community is a Climax community.

24. Succession
Primary succession: new communities develop on land that is almost lifeless.
Secondary succession: an existing community has been partially or totally destroyed and is replaced by others.

25. The human factor Growth of human population (7 billions individuals)
Limiting factors can be food availability
Carrying capacity: the size of a population supported by the environment.

27. Disruption of ecosystems
Urbanization.
Poor farming practices

28. Water Pollution Eutrophication (reduce size of lakes)
Biological magnification
Thermal pollution
Oil spills

29. Air Pollution Aerosols Acids (causing acids rains)
Chlorofluorocarbons (CFC’s) destroy the ozone layer.

32. How can we help? Controlling pollution
Conserving natural resources: recycling
Conserving soils cover crops
Conserving forests: reforestation
Conserving wildlife
Controlling pests biologically