Download Climate and Biodiversity

Climate and Biodiversity
Chapter 7
Key Concepts
• Factors influencing the Earth’s climates
• Effect of climate on Earth’s major biomes
• Characteristics of major biome types
• Major types of aquatic ecosystems
• Human impacts on the biosphere
Section 7-1
WHAT FACTORS INFLUENCE
CLIMATE?
Weather and Climate
• Climate - average temp. & precip over long term ( min. 30 yrs)
• Weather - short term temp, precip, humidity, wind, cloud, ..
• Major factors determining climate (LAPTOP)latitude, altitude, prevailing
winds, topography, ocean currents, proximity to water
• Major factors determining air circulation
1. Uneven heating of Earth’s surface- equator gets more direct sun
2. Earth’s rotation - equator rotates faster than poles- deflects air movement
3. Properties of air, water, and land- leads to 6 major convection cells
The earth has many different
climates
•Prevailing winds blowing over the oceans produce mass movements of surface water
called ocean currents. Major ocean currents and upwelling redistribute heat from the
sun, influencing climate and vegetation, especially near coastal areas.
Effects of Water, Wind, and Land
on Climate
• Ocean currents and wind- re-distribute heat, nutrients
• Gases in the atmosphere
– Greenhouse gases and the Greenhouse Effect
• Topography and local climate- rain-shadow effect
• Microclimates in urban areas- “heat island” more haze,
smog, higher temps, lower wind speeds in urban areas
bricks, asphalt, and traffic create distinct microclimates
Ocean Currents
Global Air Circulation
Energy is transferred by
convection in the atmosphere
Animation- Upwelling on Pacific
Coast of North America
This is IMPORTANT & not covered in your
text
The rain shadow effect
Animation El Niño (ENSO)
El Niño–Southern Oscillation, or
ENSO—is an example of the
interaction of land and air.
Large-scale weather
phenomenon occurring every
few years when prevailing
winds in the tropical Pacific
Ocean weaken and change
direction.
Above-average warming of
Pacific waters can affect
populations of marine species
by changing the distribution of
plant nutrients.
El Niño Southern Oscillation (ENSO)
interaction.
IMPORTANT
El Niño Southern Oscillation (ENSO)
• Offshore surface winds weaken
•Upwelling of cold, deep, nutrient-rich water weakens
•Surface waters warm off of South America
•Decrease in nutrients reduces primary productivity
•If pattern lasts 1 year or longer, it can disrupt plankton, fish and
seabirds in upwelling areas and trigger extreme weather changes
over much of the globe.
Consequences of 1996-1998 El Niño
•CA- huge waves, torrential rains, flooding & mudslides
•Peru - floods & mudslides : hundreds dead, 1/4 million homeless
•Drought Brazil, Indonesia & Australia = wildfires
•Fewer hurricanes in S.E. USA
El Niño Southern Oscillation (ENSO)
Greenhouse gases warm the
lower atmosphere
•The major greenhouse gases are:
–Water vapor (H2O).
–Carbon dioxide (CO2).
–Methane (CH4).
–Nitrous oxide (N2O).
Section 7-2 will be supported by student presentations
Section 7-2
HOW DOES CLIMATE AFFECT THE
NATURE AND LOCATION OF
BIOMES?
Biomes
• Biomes are large regions, each characterized by
certain types of climate and dominant plant life.
• Climate effects on biomes - Average annual
precipitation and temperature lead to the formation
• 10 major biomes
• Biomes are not uniform (“mosaic of patches”)
• Effects of latitude and longitude
The earth’s major biomes
Average precipitation and temperature
are determining factors
Biomes: Climate and Life
Summary
• Deserts (←25cm)
Precipitation determines whether
area is desert/grassland/forest
Temperature determines type of
desert/grassland/forest
• Grassland (25-75cm)
Shrublands fit in here
• Forests (75cm→)
• LAPTOP determines climate
(precipitation and temperature).
i.e. Mountains
• ALSO: Aquatic biomes
Biomes and climate both change
with elevation and latitude
Tropic of
Cancer
Equator
High mountains
Polar ice
Arctic tundra (cold grassland)
Temperate grassland
Tropical grassland (savanna)
Chaparral
Tropic of
Capricorn
Coniferous forest
Temperate deciduous forest
Temperate rain forest
Tropical rain forest
Tropical dry forest
Desert
END PART 1
Fig. 7-9, p.
There are three major types of
desert
•Deserts have low annual precipitation often
scattered unevenly throughout the year. The sun
warms the ground during the day and evaporates
water; heat is quickly lost at night.
•Tropical deserts are hot and dry most of the year,
with few plants.
•Temperate deserts have high daytime
temperatures in summer and low in winter. Sparse
vegetation is mostly cacti and other succulents.
There are three major types of
desert
•Cold deserts have sparse vegetation, cold
summers and precipitation is low.
•Desert soils take from decades to centuries to
recover from disturbances such as off-road vehicle
travel because deserts have slow plant growth, low
species diversity, slow nutrient cycling, and very
little water.
Typical variations in annual temperature
(red) and precipitation (blue) in deserts
There are three major types of
grasslands
•Grasslands occur mostly in the interiors of
continents in areas too moist for deserts and
too dry for forests.
•Grasslands are not taken over by shrubs
and trees because of seasonal droughts,
grazing by large herbivores, and occasional
fires.
There are three major types of
grasslands
•The three main types of grassland:
–Tropical (e.g. savanna): Savanna contains widely
scattered clumps of trees and is usually warm year-round
with alternating dry and wet seasons
–Temperate (e.g. short-grass and tall-grass
prairies):Temperate grassland winters can be very cold,
summers are hot and dry, and annual precipitation is
fairly sparse and falls unevenly through the year.
–Cold (e.g. cold grasslands or arctic tundra): Cold
grasslands, or arctic tundra, are bitterly cold, treeless
plains.
•Permafrost forms when frozen underground soil exists for more
than two consecutive years.
Typical variations in annual temperature
(red) and precipitation (blue) in grasslands
Some components and interactions
in an arctic tundra ecosystem
There are three major types of
forests
•Forests are lands dominated by trees.
•The three main types of forest:
–Tropical: Found near the equator with a warm
and wet climate; ideal for a wide variety of plants
and animals.
•Dominated by broadleaf evergreen plants keep most of
their leaves year-round. There is little vegetation on the
forest floor because the dense tree-top canopy blocks
most light from reaching the ground.
•Very high net primary productivity and an incredible
high level of biological diversity.
There are three major types of
forests
•Cover about 2% of the earth’s land surface but are
estimated to contain at least 50% of the earth’s known
terrestrial plant and animal species
–Temperate:
•Cool temperatures slow decomposition, so have a thick
layer of slowly decaying leaf litter which is a storehouse
of nutrients
–Cold: northern coniferous (cone-bearing) and
boreal.
•Winters are long and extremely cold. Plant diversity is
low, decomposition is slow.
Typical variations in annual temperature
(red) and precipitation (blue) in forests
Specialized plant and animal niches
are stratified in a tropical rain forest
Components and interactions in a temperate
deciduous forest ecosystem in North America
Mountains play important
ecological roles
•Mountains are steep or high-elevation lands where
dramatic changes in altitude, slope, climate, soil, and
vegetation take place over a very short distance.
•About 1.2 billion people (17% of the world’s population)
live in mountain ranges or their foothills, and 4 billion
people (57% of the world’s population) depend on
mountain systems for all or some of their water.
•Many mountains are islands of biodiversity surrounded
by a sea of lower-elevation landscapes transformed by
human activities.
Mountains play important
ecological roles
•Important ecological roles include:
–Contain the majority of the world’s trees
–Provide habitats for endemic species
–Have sanctuaries for species that can migrate
and surviving in higher altitudes if they are driven
from lowlands by human activities or a warming
climate..
•Mountains play a critical role in the
hydrologic cycle by serving as major
storehouses of water.
END PART 2
Section 7-3
HOW HAVE HUMAN ACTIVITIES
AFFECTED THE WORLD’S
TERRESTRIAL ECOSYSTEMS?
Natural Capital Degradation
Major Human Impacts on Terrestrial Ecosystems
Deserts
Grasslands
Large desert cities
Conversion to
cropland
Destruction of soil
and underground
habitat by off-road
vehicles
Release of CO2
to atmosphere
from burning
grassland
Depletion of
groundwater
Land disturbance
and pollution from
mineral extraction
Overgrazing
by livestock
Oil production
and off-road
vehicles in
arctic tundra
Forests
Clearing for
agriculture,
livestock grazing,
timber, and urban
development
Conversion of
diverse forests to
tree plantations
Damage from offroad vehicles
Pollution of forest
streams
Mountains
Agriculture
Timber and
mineral extraction
Hydroelectric dams
and reservoirs
Air pollution blowing in from
urban areas and power plants
Soil damage from off-road
vehicles
Stepped Art
Fig. 7-18, p.
WHAT ARE THE MAJOR TYPES OF
AQUATIC SYSTEMS? S
7-4
ECTION
Most of the earth is covered
with water
•About 71% of the earth’s surface is covered
with salty ocean water.
•One global ocean, divided it into four large
areas by geographers.
–Atlantic Ocean.
–Pacific Ocean.
•The largest; contains more than half of the earth’s
water and covers one-third of the earth’s surface.
–Arctic Ocean.
–Indian Ocean.
Most of the earth is covered
with water
•Aquatic life zones are the aquatic counterparts of
biomes
•Distribution of aquatic organisms is determined
largely by the water’s salinity—the amounts of
various salts such as sodium chloride (NaCl)
dissolved in a given volume of water.
•Zones are classified into two major types:
–Saltwater or marine life zones: Oceans and their bays,
estuaries, and other coastal systems.
–Freshwater life zones: Lakes, rivers, streams, and
inland wetlands.
Most of the earth is covered
with water
•Four major types of aquatic organisms:
–Plankton are weakly swimming and freefloating. Types include:
•Phytoplankton: photosynthesizers, includes many
types of algae.
•Zooplankton: plankton that feed on other plankton.
•Ultraplankton: huge populations of photosynthetic
bacteria.
–Nekton are strong-swimming consumers such
as fish, turtles, and whales.
Most of the earth is covered
with water
–Benthos are bottom dwellers. Examples
include:
•Oysters, which anchor themselves to one spot.
•Clams and some worms, which burrow into the
bottom.
•Lobsters and crabs, which walk on the sea floor.
–Decomposers (mostly bacteria), which break
down organic compounds in the dead bodies
and wastes of aquatic organisms.
Most of the earth is covered
with water
•Key factors determining the type and
number of organisms at various depths
include:
–Water temperature.
–Dissolved oxygen content.
–Availability of food.
–Availability of light and nutrients required for
photosynthesis.
Section 7-5
WHY ARE MARINE AQUATIC SYSTEMS
IMPORTANT AND HOW HAVE WE
AFFECTED THEM?
Marine ecosystems
Coastal Zones
estuaries, coastal wetlands, coral reefs, barrier islands, and beaches
1.
Shallow - high tide mark to edge of continental shelf
2.Warm
3. Nutrient rich
4. High primary productivity
5. < 10% of the ocean’s area, contains 90% of all marine species and most
fisheries
➢ Plenty of sunlight and nutrients from land get mixed by wind and water currents
Major life zones and vertical
zones in an ocean
Learn this diagram!
Coral Reefs
Threats
Ecological Importance
1.
Support 25% of all
marine species (66% fish)
1.
Dredging, overfishing,
dynamite fishing
2.
2.
Aesthetic beauty
3.
Protect 15% coastline from
erosion (reduce wave energy)
4.
Cycle carbon - require
CO2 for shell formation
5.
Produce chemicals useful for
medical research
Coral Bleaching Suspended sediment caused by
erosion of soil on land
smother polyps, blocks
sunlight
3.
Development of coastal zones
4.
Ocean warming/ Global
warming, ACIDIFICATION
5.
Oil spills mining, damage by
tourists, chemical pollution,
nuclear testing, and anchor
damage
A healthy coral reef and a
bleached one
Major threats to marine
ecosystems by humans
Section 7-6
WHAT ARE THE MAJOR TYPES OF
FRESHWATER SYSTEMS AND HOW HAVE
HUMAN ACTIVITIES AFFECTED THEM?
Typical distinct zones of life in fairly
deep temperate-zone lakes
The effect of nutrient
enrichment on a lake
Eutrophic- “overOligotrophic – low nutrients nourished”
Nutrients in Lakes: Oligotrophic
Figure not in text!
Nutrients in Lakes: Eutrophic
Figure not in text!
Freshwater systems provide
many important services
Lake Stratification & Turnover
Water is MOST
dense at 4°C
In the Fall, water cools
to 4°C and sinks to
bottom. This drives
Fall turnover.
Freshwater streams and rivers carry
water from the mountains to the oceans
•Surface water becomes runoff when it flows into
streams or lakes.
•A watershed, or drainage basin, is the land area
that delivers runoff, sediment, and dissolved
substances to a stream or lake.
•The downward flow of water from mountain
highlands to the sea typically takes place in three
aquatic life zones characterized by different
environmental conditions:
–The source zone, the transition zone, and the
floodplain zone.
Three zones in the downward
flow of water
Human Impacts on Freshwater
Systems
➢Dams, diversions and canals
➢Flood control levees and dikes
➢Wetland destruction
➢ Pollutants from cities and farmlandsCultural eutrophication
Three big ideas
•Differences in climate, based mostly on long-term
differences in average temperature and precipitation, largely
determine the types and locations of the earth’s biomes:
deserts, grasslands, and forests.
•Saltwater and freshwater aquatic systems cover almost
three-fourths of the earth’s surface, and oceans dominate
the planet.
•The earth’s terrestrial and aquatic systems provide
important ecological and economic services, which are
being degraded and disrupted by human activities.
END