Ecology - sciencewithmrsb.comsciencewithmrsb.com/wp-content/uploads/2016/09/Ecosystems_Biom… ·...
Transcript of Ecology - sciencewithmrsb.comsciencewithmrsb.com/wp-content/uploads/2016/09/Ecosystems_Biom… ·...
Ecology
‣ Ecology is the study of the relationships between organisms and their physicaland biotic environment:
Relationships involve
interactions with the physical
world as well as interrelationships with other
species and individuals of the
same species.
O2
Nutrients
CO2
‣ Living organisms can be studied at different levels ofcomplexity.
‣ From least to most complex, these levels are (in an ecological context):
Individual
Population
Community
Ecosystem
Biome
Biosphere
Biological Complexity
Biosphere
Biome
Ecosystem
Community
Population
Individual
‣ The biosphere isthe region within which all living things are found on Earth.
‣ It is the narrow belt around the Earth extending from the bottom of the oceans to the upper troposphere.
The Biosphere
Image: NASA
‣ Our knowledge of what constitutes the biosphere continues to develop as scientists continue their exploration of the Earth.
‣ As we learn more about the biosphere, we find new kinds of life in areas we previously thought were lifeless!
Exploring the
Biosphere
Life exists in all places, from blind white crabs
in lightless environments...
to tube worms in the crushing ocean depths.
‣ The biosphere encompasses all living things on Earth.It comprises a number of aquatic and terrestrial biomes.
‣ Biomes are the largest geographically based biotic communities that can be conveniently recognized.
‣ Biomes within the same category have specific, characteristic features.
Biomes
Desert biome
‣ Terrestrial biomes are recognized for all the major climatic regions of the world and are classified on the basis of their predominant vegetation type.
The same biome may occur in widely separated regions.
Terrestrial Biomes
‣ Three air cells circle each hemisphere of the Earth.
The interaction of these cells is a major contributor the formation of biomes.
Biomes and Weather Cells
Dry air descends
at the poles
Polar
cell
Air rising at the
equator causes the
formation of rain
clouds
Rising air allows
cloud formation in
temperate regions
After losing its
moisture, dry air
descends
Hadley
cell Ferrel
cell
Polar Temperate Desert Tropical Desert Temperate Polar
‣ Deserts are arid regions (annual rainfall generally less than 25 cm). The hot desert biome is found in two belts, centered at 30° latitude north and south of the Equator.
‣ Hot deserts receive most of their rainfall in summer. The driest regions are in central Australia and the middle of the Sahara Desert.
The temperature range is approximately 30°C, and the winter and summer are both very warm.
Hot Deserts
Ayres Rock, Australia Sand dunes, Namibia
Temperature range: 9°C
The winter and summer are
both very warm.
Annual total rainfall: 15 cm
Example: Khartoum, Sudan 15.5°N
Physical Factors:
Hot Deserts
Khartoum
‣ The cold desert biome is found in dry regions in the mid to high latitudes, especially in the interiors of large continents. Cold deserts also occur at high altitudes in the rain shadows of mountain ranges.
‣ Cold deserts receive most of their small amount of rainfall in winter.
Cold Deserts
Arches National Park, USASierra Nevada, USA
Example: Cheyenne, Wyoming 41°N
Temperature range: 23°C
The winters are cold; summers
are much warmer.
Annual total rainfall: 38 cm
Physical Factors:
Cold Deserts
Cheyenne
‣ Tropical savannas are found in central and eastern Africa, and in tropical and subtropical regions of South America and Australia. Thorn forests are found on the equatorial sides of hot deserts.
‣ Both have mild, dry winters and mild, wet summers.
Unlike savanna, thorn forests generally lack grasses. This reflects the
increased aridity of the climate.
Savanna & Thorn Forests
Temperature range: 10.7°C
Annual total rainfall: 74 cm
Example: Kayes, Mali
14°N
Physical Factors:
Savannas
Kayes
‣ Tropical evergreen forestsare found in equatorial regions where total annual rainfall exceeds 250 cm and the dry season lasts for no more than 2-3 months. These forests are species-rich.
‣ The climate is warm and rainy all year round.
Tropical
Rainforests
Rainforest, Central America
Temperature range: 2.2°C
Annual total rainfall: 262 cm
Example: Iquitos, Peru 3°S
Physical Factors:
Tropical Rainforests
Iquitos
Temperate
Forests
‣ Temperate forests occur throughout mid latitudes where there is a high annual rainfall.
‣ Temperate forests are usually deciduous, but where seasonal fluctuations are moderated by proximity to the coast, the forests are evergreen and are termed temperate rainforests.
Temperate rainforests occur in
south-eastern Australia, New
Zealand, along the Pacific North-West coast of the United States.
Temperate deciduous forest
Temperate rainforest
Physical Factors:Temperate Forests
Temperature range: 31°C
The temperature fluctuates dramatically
between summer and winter.
Total annual rainfall: 81 cm
Ample falls throughout the year.
Example: Madison, Wisconsin
43°N
Madison
Temperate Grasslands
‣ Temperate grasslands or prairies occur in mid latitudes, in regions that are relatively dry for much of the year. They occur in many parts of the world, and include:
The Pampas of Argentina
The South African veldt
The Great Plains of the USA
‣ Grasslands are highly productive and large regions have been converted to agriculture.
Temperature range: 24°C
The temperature fluctuates widely, with hot
summers, cold winters.
In some grasslands, most precipitation occurs
in the winter. In others, the majority falls in
summer.
Total annual rainfall: 31 cm
Example: Pueblo, Colorado 38°N
Physical Factors:Temperate Grasslands
Pueblo
‣ The tundra biome is found in the Arctic and high in the mountains at all latitudes. It is dominated by low-growing perennial plants.
The Arctic tundra is very wet
even though rainfall is low and this is because the water
cannot drain down through
the permafrost (permanently frozen ground).
Tundra
Tundra: northern Canada
Arctic tundra
Temperature range: 28°C
Total annual rainfall: 23 cm
Example: Greenland
73°N
Physical Factors:
Tundra
Greenland
‣ Mountainous regions are associated with their own altitude adapted vegetation.
‣ The icy regions of the polar ice caps (the Arctic and Antarctic) form sheets of ice that extend into and over the sea.
Mountains
and Ice
Predicting Biome Distribution 1
‣ Temperature and precipitation are excellent predictors of biomedistribution. Temperature decreases from the equator to the poles.
Arctic
regio
n
Subarcti
c region
Temperate
region
Tropical
region
Polar
La
titu
din
al re
gio
ns
Equatorial
Annual precipitation (mm)
Components of an Ecosystem
Community
Physical
environment
‣ A biome is a large geographical regioncomprising natural units called ecosystems.
‣ An ecosystem encompasses the physicalenvironment and the community.
Physical
environment
Community
Biotic
factorscompetitors
symbionts
predators parasites
pathogens
Ecosystem
Abiotic
factors
atmosphere
soil
water
wind speed
wind direction
current velocity
Ecosystems Light intensity varies
Flow rate varies Rainfall level varies
‣ An ecosystem includes:
all of the organisms
(the community) …
and their physical
environment.
‣ There are many different sorts of ecosystems from natural to artificial, and they range in size from large to small.
Still water habitatFast flowing water habitat
Rock habitat Stream bank habitat
‣ A community is a naturally occurring group of organisms living together as an ecological entity; the biological part of the ecosystem.
Communities
A nudibranch snail
feeding on rock
encrusting
organisms
Environments
‣ The physical environmentrefers to the physical surroundings of any organism, including:
the medium, e.g. water
substrate, e.g. soil
climatic (atmospheric)
conditions
light …
and other physical properties.
‣ The type and extent of vegetation in a particular ecosystem is determined by physical factors on both a large scale and on a very localized (microclimate) level.
Vegetation patterns are
governed largely by climate
(which is broadly related to latitude) and altitude.
Climate and
Vegetation
High latitude climate
Temperate climate
‣ Abiotic (physical) factors are the influences of the non-living parts of the ecosystem.
Examples include pH, salinity, temperature, turbidity, wind
speed and direction, humidity,
precipitation, water pressure, and light intensity and quality.
‣ Biotic factors are the influences of the living parts of the ecosystem. Producers and consumers interact as competitors, parasites, pathogens, symbionts, and predators.
Factors Affecting Ecosystems
‣ Devices for measuring the physical
factors in the field include the
following meters:
Quantum light meter
Dissolved oxygen
Oxygen meter
pH meter
Total dissolved solids (TDS) meter
Current meter
Multi-purpose meter
Hygrometer
Wind meter
Other equipment includes:
Secchi discs
Nansen bottles
Monitoring Physical Factors
Ph
oto
: C
ou
rte
sy P
AS
CO
scie
ntific
Pasco datalogger with attached sensor
‣ Gradients in abiotic factors are found in almost every environment.
They influence habitats and
microclimates, and determine patterns of species distribution.
‣ The effects of these physical (or environmental) gradients are particularly evident where physical conditions change markedly within a short distance, e.g. in deserts, along rocky shores, in lakes and tropical rainforests, and on mountains.
Physical Gradients
‣ Desert environments experience extremes in temperature and humidity, but they are not uniform with respect to these factors.
Physical conditions vary widely within the one general environment.
Crevices, burrows, and the presence of rock overhangs and vegetation create microclimates where extremes in physical conditions are
reduced compared to the desert surface.
Desert Environments
Desert Factors
1 m above
ground
33°C, 20% humidity
300 m altitude
27°C, 20%
humidity
Desert surface
45°C, <20%
humidity
Under rock
28°C, 60% humidity
Burrow
(2 m underground)
25°C, 95%
humidity
Crack/crevice
(1 m underground)
27°C, 95%
humidity
Hypothetical values for temperature (°C) and
percentage humidity at midday in a desert environment.
‣ Rocky shore environments typically exhibit marked physical gradients as a
result of tidal movements. Horizontal and vertical gradients in salinity,
temperature, dissolved oxygen, and exposure time are reflected in the
communities found at different positions on the shore.
Horizontal: from the low tide to the high tide marks
Vertical: from the bottom to top surfaces of rocks and boulders.
Rocky Shore Environments
Rocky Shore Factors
Hypothetical values for physical
factors in rock pools at different
places on a rocky shore.
Salin: 42 gl-1
Temp: 28° C
DO: 20%
Exp: 12 h
Salin: 39 gl-1
Temp: 28° C
DO: 30%
Exp: 10 h
Salin: 38.5 gl-1
Temp: 26° C
DO: 42%
Exp: 8 h
Salin: 37 gl-1
Temp: 22° C
DO: 57%
Exp: 6 h
Salin: 36 gl-1
Temp: 19° C
DO: 74%
Exp: 4 h
Salin: 35 gl--1
Temp: 17° C
DO: 100%
Exp: 0 h
Salin: salinity
Temp: temperature
DO: dissolved oxygen
Exp: exposure time
(per 12 hour tidal cycle)
‣ The high species diversity of tropical rainforests can be supported because of the wide variety of microhabitats provided by the layered structure of the forest.
‣ The physical conditions at the uppermost level are quite different to those at the forest floor with respect to light intensity (and quality), wind speed, and humidity.
A Tropical Rainforest
Canopy
Subcanopy
Understorey
Ground layer
Rainforest Factors
Light: 70%
Wind: 15
kmh-1
Hum: 67%
Light: 50%
Wind: 12
kmh-1
Hum: 75%Light: 12%
Wind: 9 kmh-
1
Hum: 80%
Light: 6%
Wind: 5 kmh-
1
Hum: 85%Light: 1%
Wind: 3 kmh-
1
Hum: 90%
Light: 0%
Wind: 0 kmh-
1
Hum: 98%
Light: light intensity
Wind: wind speed
Hum: humidity