Terrestrial Biomes Notes

Terrestrial Biomes

Terrestrial biomes are categorized by their vegetation, rainfall, and climate.

Essential Knowledge:

  • Major terrestrial biomes: taiga, temperate rainforests, temperate seasonal forests,

Biome Characteristics

  • Biome Definition: An area that shares a combination of average yearly temperature and precipitation (climate).

  • The organisms in a biome are uniquely adapted to live there.

    • Example: Camels and cacti in deserts have water-preserving traits.

    • Example: Shrubs and wildflowers in grasslands store energy in roots to recover from fire.

  • Latitude (distance from the equator) determines temperature and precipitation, leading to predictable biome patterns.

Temperature and Precipitation

  • Temperature: Warmest at the equator, coldest at the poles due to the angle at which the sun hits the Earth.

  • Precipitation: Global rainfall depends on global wind circulation, driven by the sun.

    • Solar energy heats air at the equator, causing it to rise. The rising air cools, and moisture falls as rain.

    • Drier air spreads north and south and sinks at around 30 degrees latitude.

Temperature & Precipitation Relationship to Biomes

  • Low Temperature, Low Rainfall: Tundra

  • Low Temperature, High Rainfall: Coniferous Forest (Taiga)

  • Warm Temperature, Low Rainfall: Desert

  • Cool Temperature, Low Rainfall: Temperate Grassland

  • Cool Temperature, High Rainfall: Temperate Deciduous Forest, Temperate Rainforest

  • Warm Temperature, High Rainfall: Savanna, Tropical Deciduous Forest, Tropical Rainforest

Tropical Rainforest

  • Highest precipitation.

  • Most stable temperature due to high humidity.

  • Large tropical trees.

  • Limiting factor for plants: sunlight; epiphytes are common.

  • Highest biodiversity of terrestrial biomes.

  • Nutrient-poor soils because decaying organic matter is quickly absorbed by vegetation.

Desert

  • Hot with extremely low rainfall.

  • Located around 30° north and south of the equator.

  • Plants and animals have adaptations for low precipitation.

Savannah/Tropical Grassland

  • Open grassland with scarce shrubs and trees.

  • Located between rainforests and deserts.

  • Warm temperatures year-round (tropical).

  • Periodic fires occur.

  • Has wet and dry seasons.

  • Not enough precipitation to become forests, but enough not to be a desert.

Temperate Grasslands

  • Cooler temperatures than tropical grasslands.

  • Less dramatic wet and dry seasons.

  • Enough rain to sustain grasses (prairies), but not enough to grow forest.

  • Much lower biodiversity than tropical grasslands.

  • Known for having the richest soils.

    • Examples: Great Plains of America, Russian steppes.

    • Where the corn belt is.

Temperate Rainforest

  • Receive a lot of year-round rainfall.

  • Large old-growth trees.

  • Higher latitudes than tropical rainforests, so temperatures are cooler.

  • Alaska has the most old-growth forests in the US.

Temperate Deciduous Forest

  • Mid-latitude forest.

  • Dominated by deciduous trees (oak, hickory, elm, maple, ash) that lose leaves in winter.

  • Moderate rainfall.

  • Experience all four seasons.

Coniferous Forest, Taiga, Boreal

  • Largest terrestrial biome.

  • Higher latitude than deciduous forests.

  • Coniferous trees are pine trees that don’t lose leaves in winter.

  • Shorter growing season than deciduous forests (colder, less rain).

    • Example: Redwood forest.

Chaparral

  • Coastal biome.

  • Hot, dry summers and mild, rainy winters.

  • Spiny evergreen shrubs.

  • Maintained by fire (dry summer); needed for some seeds to germinate.

Tundra

  • A cold desert (very little precipitation).

  • Bitter cold, high winds.

  • Very short growing season.

  • Permanent ice (permafrost) underlies the surface.

  • Restricts plants from having deep roots; therefore, no trees.

  • Found in the Arctic (far north) and high mountains.

Human Impacts: Deforestation

  • Tropical Rainforest:

    • Amazon: agricultural land for crops (mostly soy) and cattle.

    • Indonesia: agricultural land for palm oil.

    • Results in loss of biodiversity and release of CO_2.

  • US:

    • Timber operations

    • More regulated (government rules, regulations, oversight; penalties for infractions, selective-cutting).

Human Impacts: Soil Erosion

  • Modern agricultural practices are degrading soil.

    • Tilling/ploughing before planting

    • Compaction & overgrazing by livestock

    • SalinatioHeating of the planet is causing weather patterns and biomes to shift, altering biodiversity.n: over-irrigation leads to a build up of salts.

  • US farmers have to add more and more fertilizer to get the same yield.

Human Impacts: Climate Change

  • Plants: Extended growing seasons.

  • Animals: Changing migration patterns.

  • Solutions: switch to renewables, tax breaks or rebates for the use of renewables, impose a “carbon tax” for use of fossil fuels.