Biomes

What are biomes? Large, distinctive areas created and maintained by climate. Major regional community of plants and animals with similar life forms and environmental conditions. Biomes are named after the dominant life form such as grassland or tropical rainforest.

Biomes can be found at certain latitudes. The major biomes are widely distributed and their distribution is primarily a product of climate and soil types. Most biomes cover large areas and occur on more than one continent.

Look back at the map to find the latitude of each biome. Tundra Taiga Temperate Deciduous Forest Scrub forest (Chaparral) Grassland Desert Tropical Rainforest Temperate Rainforest Biologists have no idea whether the lakes and oceans of the world can be organised into one biome or a hundred biomes.

Tropical Rainforests Deserts Temperate Forests Tundra

Biomes are determined largely by climate Temperature Precipitation Insolation (solar radiation) Distribution is obvious – where your biome can be found in the world. Productivity – consider diversity of animals and plants and consider differences in times of the year (growing seasons vs non-growing seasons). Climate - Where precipitation is abundant (100cm or more per year) and is fairly evenly distributed, the major determinant is temperature. It is not simply a matter of average temperature. Consider whether your biome is established by rainfall or by temperature or by another factor.

What generates Earth’s climatic regions? The Earth heats unevenly due to uneven way sunlight hits our planet. The tropics are warm and the poles are cold because the sun heats Earth’s surface unevenly. Like a flashlight beam shining directly down onto the table from above versus one coming obliquely from the side, sunlight hitting Earth directly is more intense than sunlight striking at an angle. The precise angle the sun makes at a point on the glove depends on the distance between the point and the equator (the latitude) and the season.

Climate: Insolation (incoming solar radiation) The Earth’s rotation. Temperatures fluctuate with the seasons because our planet spins on an axis tipped at a constant tile relative to the sun. Consequently, during summer, the Northern Hemisphere inclines maximally toward the sun, and receives more sunlight, while in winter, it tips away from the sun and receives less sunlight. The seasons are reversed in the Southern Hemisphere. This uneven illumination caused by Earth’s tilted axis helps explain the warm temperatures and abundant growth of organisms in summer and the cold temperatures and dormancy of living things in winter.

Climate: Precipitation . Sunlight striking the Earth heats the air. Warm air has different properties than cool air, and these account for the formation of rain and snow. Cold air weighs more than warm air, by volume, and so tends to sink. Dense, cool air holds less moisture than light warm air.

Powerful sunlight hitting the equator heats the air, which picks up moisture by evaporation from land surfaces and plant leaves. The hot, moist air rises and once aloft, cools, releasing water it can no longer hold as rain, onto the lush tropical tropical forests.

Go back to the slide before to see why.. The equator is warm and wet = tropical Deserts are found around 30o latitude Temperate forests and grasslands are around 45o latitude Tundra is found at 60o latitude

What are limiting factors? Limiting factor - the factor which limits the growth of a population because there is too little or too much of it in the environment. Biomes and ecosystems are shaped by limiting factors. Any species has a certain range of tolerance to these factors (tolerance thresholds) which set that species’ range and potential population. Every organism needs certain requirements for its survival. There are several limiting factors which determine whether an organism can live in a particular environment. Abiotic environment are things like sunshine, climate (temperature and precipitation) and nutrients from the solid earth (rocks and soils).

Tropical rain forests: 0-10o latitude

Tropical Rainforests 365 days of sunlight Year round growing seasons Warm temperatures year round Abundant rainfall The most productive biome Poor soil

Tropical soil is low in organic matter and tends to be oxidized.

Deserts: 30 north and south of the equator

Desert biomes Abundant sunshine Temperature varies Extremely low Precipitation Low productivity Water is the limiting factor

Desert soils are low in organic matter as they have little vegetation

Temperate Forest Biomes

Temperate forests Cold winters Warm wet summers Growing season only in summer months Leaves fall in autumn Soil high in organic matter Productive farm land

Temperate soil profile

Temperate Grasslands Cold winters Spring rain Warm summers Dry in late summer Grass becomes dormant in winter and adds organic matter to the soil. Soil is fertile from build up of organic matter (good topsoil for agriculture)

Temperate grassland soil profile

Chapparal /Mediterranean Biome

Chaparral (Mediterranean) Hot, dry summers Mild winters with Moisture Like Santiago

Taiga, boreal forest, coniferous forest

Taiga

latitudes 55°  to 70° North

Tundra Cold, dark winters Short growing seasons Permafrost Low productivity

Arctic Tundra

Tundra soil profile

Permafrost

Things to remember: The climate determines the biomes Biomes are mainly located along lines of latitude on the planet Productive biomes have longer growing seasons than less productive biomes Temperate biomes have good conditions for soil formation

Be able to: Link biomes to agriculture Link biomes to carbon dioxide intake of growing plants Link biomes to soil formation