Major Ecosystems of the World Chapter 6. Earth’s Major Biomes

Major Ecosystems of

the World

Chapter 6

Earth’s Major Biomes

Earth’s Major Biomes

Type of biome controlled by temperature and precipitation

Earth’s Major Biomes

Tundra

Earth’s Major Biomes

Tundra

Characterized by:

• Very short growing season

• Little precipitation (10-25 cm / yr)

• Permafrost

• Low species diversity

Earth’s Major Biomes

Boreal Forest (Tiaga)

Earth’s Major Biomes

Boreal Forest (Tiaga)

Characterized by:

• Short growing season

• Low precipitation (~50 cm / yr)

• Dominated by conifers (spruce, fir), but also has aspen, birch

Earth’s Major Biomes

Temperate Rain Forest

Earth’s Major Biomes

Temperate Rain Forest

Characterized by:

• Cool; high precipitation (~127 cm / yr)

• Dominated by evergreens (hemlock, spruce, cedar)

• Heavily logged

Earth’s Major Biomes

Temperate Deciduous Forest

Earth’s Major Biomes

Temperate Deciduous Forest

Characterized by:

• Hot summers, cold winters

• Moderate precipitation (75-150 cm / yr)

• Dominated by oaks, hickory, maple

• Commonly converted to agriculture

Earth’s Major Biomes

Grasslands

Earth’s Major Biomes

Grasslands

Characterized by:

• Hot summers, cold winters

• Low to moderate precipitation (25-75 cm / yr)

• Dominated tallgrass or shortgrass prairies

• Heavily converted to agriculture

Earth’s Major Biomes

Chaparral

Earth’s Major Biomes

Chaparral

Characterized by:

• Dry summers, mild winters

• Frequent fires

• Dominated by short pines, evergreen shrubs, scrub oak (but varies worldwide)

Earth’s Major Biomes

Deserts

Earth’s Major Biomes

Deserts

Characterized by:

• Wide daily variations in temperature

• Very dry (<25 cm precipitation / yr)

• Sparse plant coverage

Earth’s Major Biomes

Savanna

Earth’s Major Biomes

Savanna

Characterized by:

• Precipitation 76-150 cm / yr, but very seasonal with extended dry periods

• Dominated by grasses, with occasional trees

• African most famous for herds of wildebeest, antelope, zebra

Earth’s Major Biomes

Tropical Rain Forests

Earth’s Major Biomes

Tropical Rain Forests

Characterized by:

• Very high precipitation 200-450 cm / yr

• Very nutrient-poor soil

• Extremely high primary productivity

• Extremely high species richness

Earth’s Major Biomes

Vertical Zonation: The Distribution of Vegetation on Mountains

Aquatic EcosystemsFundamental division:

Freshwater vs. Saltwater

But, both contain 3 ecological category of organisms:

•Free floating plankton•Strongly swimming nekton•Bottom-dwelling benthos

Aquatic Ecosystems

Freshwater Ecosystems

Rivers and Streams•Tend to be narrow, swift, clear, cold, nutrient poor, and highly oxygenated

•Tend to be wide, slow, cloudy, warm, nutrient rich, and less oxygenated

Aquatic Ecosystems

Freshwater Ecosystems

Lakes and Ponds

Highly productive, high species richness

Photosynthetically productive; large fish

Aquatic Ecosystems

Freshwater Ecosystems

Lakes and Ponds

Not always present; anaerobic, dominated by decomposers

Aquatic Ecosystems

Freshwater Ecosystems

Thermal stratification in temperate lakes

Thermal Stratification - marked layering of large temperate lakes caused by how far light penetrates

Thermocline - an abrupt temperature transition where the cooler denser water remains at the bottom while the warm, less dense water remains at the top

Aquatic Ecosystems

Freshwater EcosystemsFall and Spring Turnover in temperate lakes

Fall Turnover - a mixing of the layers; as surface water cools, its density increases and it displaces the less dense, warmer, mineral-rich water beneath and the warmer water rises to the surface where it cools and sinks

Spring Turnover - the ice melts and the surface water sinks to the bottom and the bottom water rises to the surface

Why is Turnover Essential?

Aquatic Ecosystems

Freshwater Ecosystems

Marshes and Swamps•Highly productive

•Nutrient rich due to slow decomposition

•Remove many pollutants

What is the difference between a swamp and a

marshland?

Aquatic Ecosystems

Estuaries: Where freshwater and saltwater meet.

• Highly variable environment

(salinity, temperature, light penetration rapidly changes).

• Many fishes and shellfish spend larval stages here.

Aquatic Ecosystems

Estuaries

Two general types:

1) Salt marshes

2) Mangrove forests

What is the difference between a salt marsh

and a mangrove forest?

Aquatic EcosystemsCase-in-Point: The Chesapeake Bay

Largest Estuary in the US

--most productive estuary in the US

--nine rivers and 150 streams empty into the bay

-- Home to more than 1 million people

--deteriorating water quality due to pollution

--overfishing

--loss of habitat

-- sedimentation

Aquatic Ecosystems

Marine Ecosystems

Three Main Life Zones -

-- Intertidal Zone

-- Benthic Environment

-- Abyssal Zone

-- Hadal Zone

-- Pelagic Environment

-- Neritic Province-- Oceanic Province

Aquatic Ecosystems

Marine Ecosystems

Intertidal Zone

Aquatic Ecosystems

Marine Ecosystems

Benthic EnvironmentPhotic benthic environments include:

1) Sea grasses

Aquatic Ecosystems

Marine Ecosystems

Benthic EnvironmentPhotic benthic environments include:

1) Sea grasses

2) Kelp forests

Aquatic Ecosystems

Marine Ecosystems

Benthic EnvironmentPhotic benthic environments include:

1) Sea grasses

2) Kelp forests

3) Coral reefs

Aquatic Ecosystems

Types of Coral Reefs

(a) Fringing reef

Aquatic Ecosystems

Types of Coral Reefs

(b) Atoll

Aquatic Ecosystems

Types of Coral Reefs

(c) Barrier reef

Aquatic Ecosystems

Human Impacts on Coral Reefs

• Sedimentation / siltation

• Pollution

• Overfishing

• Direct disturbance (anchor dragging, divers damaging / collecting specimens)

Aquatic Ecosystems

Marine Ecosystems

The Neritic Province

Dominated by floating and swimming organisms.

Such as many large fishes, sea jellies, various plankton.

Aquatic Ecosystems

Marine EcosystemsThe Oceanic Province

Largest area of ocean

Least explored area

Aquatic EcosystemsHuman Impacts on the Ocean

Aquatic Ecosystems

Human Impacts on the Ocean

Interaction of Life Zones

Case-in-Point: The Everglades