major ecosystems of the world chapter 6. earth’s major biomes
TRANSCRIPT
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