biomes notes

Terrestrial Biomes Overview

• Terrestrial biomes range from tundra to tropical forests.

• There are nine primary terrestrial biomes:

  • Tundra

  • Boreal forest (taiga)

  • Temperate rainforest

  • Temperate seasonal forest

  • Woodland/shrubland

  • Temperate grassland/cold desert

  • Tropical rainforest

  • Tropical seasonal forest/savanna

  • Subtropical desert

Tundra

• A cold, treeless biome with low-growing vegetation.

• Features:

  • Soil is completely frozen in winter.

  • Short growing season (approximately 4 months during summer).

  • Underlying subsoil called permafrost:

    • An impermeable, permanently frozen layer of soil.

Boreal Forest (Taiga)

• Made up primarily of coniferous evergreen trees that tolerate cold winters and short growing seasons.

• Found between 50˚ and 60˚ N in Europe, Russia, and North America.

• Climate:

  • Very cold with plant growth constrained by temperature more than precipitation.

• Soil:

  • Nutrient-poor due to slow decomposition.

Temperate Rainforest

• A coastal biome characterized by moderate temperatures and high precipitation.

• Location:

  • Found along the west coast of North America from northern California to Alaska, also in southern Chile, New Zealand, and Tasmania.

• Growing Season:

  • Nearly 12 months, with rainy winters and foggy summers.

• Supports large trees due to mild temperatures and high precipitation.

Temperate Seasonal Forest

• A biome with warm summers and cold winters, receiving over 1 m (39 inches) of precipitation annually.

• Location:

  • Found in the eastern United States, Japan, China, Europe, Chile, and eastern Australia.

• Vegetation:

  • Dominated by broadleaf deciduous trees like beech, maple, oak, and hickory.

• Soil:

  • Generally more nutrient-rich than boreal forests due to warmer summer temperatures favoring decomposition.

Woodland/Shrubland

• Characterized by hot, dry summers and mild, rainy winters.

• Location:

  • Found in southern California, southern Australia, southern Africa, and around the Mediterranean Sea.

• Growing Season:

  • 12-month growing season constrained by low summer precipitation and low winter temperatures.

• Adaptations:

  • Plant species are well adapted to fire and drought; wildfires are common.

Temperate Grassland/Cold Desert

• Characterized by cold, harsh winters and hot, dry summers.

• Features:

  • Lowest average annual precipitation of any temperate biome.

• Location:

  • Found in the Great Plains of North America, South America, and central Asia/eastern Europe.

• Plant Growth:

  • Inhibited by insufficient summer precipitation and cold winter temperatures.

  • Dominated by grasses and nonwoody flowering plants adapted to wildfires and grazing.

Tropical Rainforest

• A warm and wet biome located between 20°N and 20°S of the equator.

• Characteristics:

  • Little seasonal temperature variation and high precipitation, with average annual temperatures exceeding 20˚C.

• Location:

  • Found in Central/South America, Africa, Southeast Asia, and northeastern Australia.

• Biodiversity:

  • Contains more biodiversity per hectare than any other terrestrial biome, housing up to two-thirds of Earth's terrestrial species.

Tropical Seasonal Forest/Savanna

• Marked by warm temperatures and distinct wet and dry seasons.

• Location:

  • Common in Central America, the Atlantic coast of South America, southern Asia, northwestern Australia, and sub-Saharan Africa.

• Soil Characteristics:

  • Fairly fertile but low precipitation constrains plant nutrient uptake.

• Vegetation:

  • Consists of grasses and scattered deciduous trees.

Subtropical Desert

• A biome prevailing at approximately 30°N and 30°S, characterized by hot temperatures and extremely dry conditions.

• Locations:

  • Includes the Mojave Desert, the Sahara, the Arabian Desert, and the Great Victoria Desert.

• Vegetation:

  • Includes cacti, euphorbs, and other succulent plants adapted to harsh conditions.

Freshwater Biomes Overview

• Freshwater biomes have low salinity and include:

  • Streams and rivers

  • Lakes and ponds

  • Freshwater wetlands

• They are often sources of drinking water.

Streams and Rivers

• Flowing freshwater that originates from underground springs or rain/melting snow runoff.

• Streams:

  • Narrow and carry small amounts of water.

• Rivers:

  • Wider and carry larger water volumes.

Lakes and Ponds

• Contain standing water, some too deep for emergent vegetation.

• Lakes:

  • Larger than ponds, without a clear size distinction for lakes and ponds.

• Zones in Lakes:

  • Littoral Zone: Shallow area where algae and emergent plants grow.

  • Limnetic Zone: Open water for deeper aquatic plants.

  • Profundal Zone: Sunlight-restricted region below the limnetic zone.

  • Benthic Zone: Muddy bottom substrate.

Freshwater Wetlands

• An aquatic biome submerged or saturated by water for part of the year, supporting emergent vegetation.

• Known for high productivity.

Marine Biomes Overview

• Marine biomes have high salinity, including:

  • Salt marsh

  • Mangrove swamp

  • Intertidal zone

  • Coral reefs

  • Open ocean

Salt Marsh

• A marsh with non-woody emergent vegetation, found in temperate climates.

• Highly productive biome.

Mangrove Swamp

• Coastal swamps with salt-tolerant trees, roots submerged in water.

• Protect coastlines from erosion and storm damage.

Intertidal Zone

• Coastal region between high tide and low tide levels.

• Challenges for organisms include wave action and varying water levels.

Coral Reefs

• Most diverse marine biome, found in warm, shallow waters beyond shorelines.

• Coral Bleaching:

  • Occurs when algae in corals die, turning corals white due to stress.

Open Ocean

• Deep, sunlit area of the ocean away from shore, with two zones:

  • Photic Zone: Upper layer receiving sunlight for photosynthesis.

  • Aphotic Zone: Deeper layer without enough sunlight.

• Chemosynthesis: Process used by some bacteria to generate energy using methane and hydrogen sulfide.