Transcript Geographical Ecology, Climate and Biomes

AP Environmental Science
Terrestrial Biodiversity
and
Climate
© Brooks/Cole Publishing Company / ITP
1. Weather & Climate
What is the difference between weather and climate?
• Weather- short–term properties of troposphere
(temperature, pressure, humidity, precipitation,
solar radiation, cloud cover, wind direction and
speed)
• Troposphere- the lowermost atmospheric layer
where weather occurs
• Climate- general, long–term weather of a region.
• Global temperature and precipitation patterns
are determined by uneven heating of Earth by Sun
and lead to distinct climate zones according to
latitude.
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Climate
is
the average weather patterns for an area over
a long period of time (30 - 1,000,000 years).
It is determined by
Average Precipitation
and
Average Temperature
which are influenced by
latitude
altitude
ocean currents
and affects
where people live
how people live
what they
grow and eat
Climate: Global Patterns
Major factors influencing climate:
•
Air circulation patterns which are determined by
1. Uneven heating of Earth's surfaceuneven heating of
troposphere from beneath.
2. Seasonal changes in temp and precipitation due to Earth's
tilt on axis and revolution about the sun
3. Earth's rotation on its axis
4. Special properties of air, water, and land affect global air
circulation (land absorbs heat faster than water but water
releases the heat slower)
5. Wind Formation
•
Ocean currents (water circulation)
-
Influenced by factors that influence air circulation plus
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differences in water density.
Climate: Air Circulation Patterns
Uneven Heating of Earth’s Surface
Earth's tilted axis
(23.5º) causes
more direct sunlight
at equator and
more dispersed
sunlight at higher
latitudes.
This plays a major
role in weather and
climate.
Fig. 7–3
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Air Circulation Patterns:
Rotation of Earth on Axis


Earth’s surface turns
faster under equator than
at poles
This deflects the
movements of winds
moving N or S to the W at
the equator and the E
closer to the poles.
Air Circulation Patterns:
Special Properties of Air, Water
and Land
Air circulation patterns,
such as vertical
convection currents, mix
air in the troposphere and
transport heat and water
from one area to another
in circular convection
cells, called Hadley cells.
Fig. 7–5
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Global Air Circulation Patterns
Conceptual model of global air circulation and biomes.
Fig. 7–6
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Greenhouse Effect
The greenhouse
effect- a natural
process in which
heat–trapping
gases (CO2, H2O,
etc.) trap heat in
the troposphere.
Without the
greenhouse effect,
Earth would be
cold and lifeless.
Fig. 7–9
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Climate: Ocean Currents
Major patterns:
• Ocean current kinetic energy (in form of heat)
transferred from air circulation (winds) to water at
ocean surface
solar energy –> wind kinetic energy –> ocean kinetic energy
• Deep currents driven by cooling and by increased
salinity – both make water denser and cause to sink;
• Currents redistribute heat and moderate coastal
climate
Example: Gulf stream brings warm water far north
to cause NW Europe to be warm (otherwise Europe
would have subarctic climate).
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Weather & Climate
Fig. 7–2
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Currents: Upwelling
Upwelling- a process that
brings deep, cool,
nutrient–rich waters up to
replace surface water,
leading to increased
primary productivity, with
large populations of
phytoplankton,
zooplankton, fish, and
fish–eating birds.
Fig. 7–7
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El Niño–Southern Oscillation (ENSO)
 ENSO- A periodic shift in global climate conditions
(every 3–4 yrs)
Western flowing (called “easterly”) winds in the Pacific
Ocean weaken or cease
Surface water along N. and S. America become warmer
Upwelling decreases
Primary productivity along the S.A. coast declines sharply
***Strong ENSO affects over two–thirds of the globe.
Earth System: El Niño
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El Niño–Southern Oscillation (ENSO)
Fig. 7–8
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El Niño
Drought
Unusually high rainfall
Unusually warm periods
Microclimate
 Topography, water bodies and other local features create local climate
conditions different from the norm known as microclimate.
Mountains commonly result in high rainfall on the windward side and
low rainfall in the rain shadow of the leeward side.
Urban areas with lots of brick, asphalt and concrete absorb sunlight
and reradiate it as heat to the air.
Fig. 7–10
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2. Biomes
Varying climates lead to varying communities of organisms.
Biomes- the major types of terrestrial ecosystems
• **Determined primarily by climate (precipitation and temperature)
• Major groupings of biomes (desert, grassland, forest and mountain)
found in tropical, temperate and arctic conditions.
• Similar traits of plants and animals for biomes of different parts of
world; because of similar climate and evolutionary pressures
(convergence)
• Types of plants in a biome
is dictated by precipitation
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Biomes: Desert, Grassland,
Forest and Mountain
Earth's major
biomes.
Fig. 7–11
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3. Desert Biomes
Climate graphs showing typical variation in annual
temperature and precipitation for tropical,
temperate and polar deserts.
EVAPORATION EXCEEDS PRECIPITATION
Fig. 7–14
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Characteristics:
Desert Biomes
• Low precipitation--< 25 cm (10 in) annually
• Sparse, widely spaced, mostly low vegetation
• 30% of land surface, especially at 30° N and
30° S latitude
• Largest on interiors of continents;
• Plants typically deep rooted shrubs with small
leaves, succulents, or short–lived species that
flourish after rain
• Animals typically nocturnal and have physical
adaptations for conserving water and dealing
with heat
• FRAGILE BIOME DUE TO LONG
REGENERATION TIME OF VEGETATION
WHEN DESTROYED!
• American Field Guide Viewer-Deserts
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Natural Capital Degradation
Deserts
Large desert cities
Soil destruction by offroad vehicles and urban
development
Soil salinization from
irrigation
Depletion of underground
water supplies
Land disturbance and
pollution from mineral
extraction
Storage of toxic and
radioactive wastes
Large arrays of solar
cells and solar collectors
used to produce
electricity
4. Grassland, Tundra and Chaparral
Biomes
•Climate graphs showing typical variations in annual
temperature and precipitation in tropical (savannas),
temperate and polar grasslands (tundras)
•THE ARCTIC TUNDRA IS THE MOST FRAGILE
BIOME!!—bitter cold, slow rate of plant growth and
decomposition, therefore shallow soil.
Fig. 7–17
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Grassland Biomes
Characteristics:
• Sufficient rainfall to support grass, but
often too dry for forests
• Mostly on interiors of continents
• Maintained by seasonal drought,
grazing and periodic fires that prevent
invasion by shrubs and trees
• High diversity of grasses and
herbaceous plants that typically have
resistance to drought, grazing and fire
• **Fertile topsoil EXCEPT in arctic
tundra
• Animals include large and small
herbivores, along with predators
adapted to feed on these herbivores.
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Grassland Biomes: Chaparral
Characteristics:
 Found in many coastal
regions that border on
deserts (i.e. California)
 Temperate shrubland
 Consists of dense
growths of low-growing
evergreen shrubs and
small trees
 Very susceptible to fires,
but is also maintained by
them
Natural Capital Degradation
Grasslands
Conversion of savanna and
temperate grasslands to cropland
Release of CO2 to atmosphere from
burning and conversion of
grassland to cropland
Overgrazing of tropical and
temperate grasslands by livestock
Damage to fragile arctic tundra by
oil production, air and water
pollution, and off-road vehicles
5. Forest Biomes
Climate graphs showing typical variations in annual
temperature and precipitation in tropical, temperate
and polar forests (boreal, or taiga).
Fig. 7–22
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Forest Biomes
Characteristics:
• Sufficient rainfall to support growth of
trees but soil nutrients are major
limiting factor
• 3 types:
- Tropical, typically broadleaf evergreen
trees with high diversity (2% of Earth’s
surface but are habitats for at least
50% of our Earth’s terrestrial species)
- Temperate, typically deciduous
broadleaf tree with moderate diversity
and **nutrient rich soil
- Boreal (taiga), typical conifers (needle
leaves) with low diversity. American
Field Guide Viewer--Taiga
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Forest Biomes
• Community of plants and
animals typically distributed in
various layers and various
niches:
- Understory of herbaceous
plants and shrubs
- Subcanopy of tree
saplings
- Canopy of full grown trees.
- Emergent layer gets most
direct sunlight
Natural Capital Degradation
Forests
Clearing and degradation of tropical
forests for agriculture, livestock
grazing, and timber harvesting
Clearing of temperate deciduous
forests in Europe, Asia, and North
America for timber, agriculture, and
urban development
Clearing of evergreen coniferous
forests in North America, Finland,
Sweden, Canada, Siberia, and Russia
Conversion of diverse forests to
less biodiverse tree plantations
Damage to soils from off-road
vehicles
6. Mountain Biomes
•Similar changes in vegetation type occur when increasing latitude
or increasing altitude
•Each 100 m (300 ft) gain in elevation is approximately equal to a 100
km (62 mi) change in latitude
Altitude
Mountain
Ice and snow
Tundra (herbs,
lichens,
mosses)
Coniferous
Forest
Deciduous
Forest
Tropical
Forest
Latitude
Tropical
Forest
Deciduous
Forest
Coniferous
Forest
Tundra (herbs,
lichens, mosses)
Polar ice
and snow
Mountain Biomes
Characteristics:
• Diversity of habitat because of altitude,
slope orientation, corresponding
microclimate and soil over short distances;
• Complex patterning of vegetation
• 20% of Earth's surface
• Majority of world's forests
• Timberline- elevation above which
trees do not grow
• Snowline- elevation above which
there is permanent snow
• Important as watersheds for lowlands.
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Natural Capital Degradation
Mountains
Landless poor migrating
uphill to survive
Timber extraction
Mineral resource extraction
Hydroelectric dams and
reservoirs
Increasing tourism (such
as hiking and skiing)
Air pollution from industrial
and urban centers
Increased ultraviolet radiation from ozone depletion
Soil damage from off-road
vehicles
7. Perspectives on Geographical
Ecology
• Important Lessons
- Everything is connected
- Temperature and precipitation result patterns result
from interplay of incoming solar radiation and
geometry of Earth's rotation and orbit
- Temperature and precipitation are major
determinants of the distribution of organisms
- Understanding the range of biodiversity and its
distribution provides a global perspective.
- Teachers' Domain: Earth as a System
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