chapt23_lecture Humans and Ecology

Human Biology
Sylvia S. Mader
Michael Windelspecht
Chapter 23
Global Ecology
and Human
Interferences
Lecture Outline
See separate FlexArt PowerPoint slides
for all figures and tables pre-inserted into
PowerPoint without notes.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Points to Ponder
• What is an ecosystem and what are its biotic components?
• What are the energy flow and chemical cycling in an
ecosystem?
• What are the two major ecosystems on earth?
• Describe the 3 types of terrestrial ecosystems and the 2 types
of aquatic ecosystems.
• Compare and contrast food webs and food pyramids.
• What is a biogeochemical cycle?
• What is a reservoir and an exchange pool.
• Explain the water, carbon, nitrogen, and phosphorus cycles.
• What human activities interfere with these cycles?
• What problems are we creating by altering these pathways?
• What is ozone depletion and why is this important?
• What are the pros and cons to drilling in the Arctic National
Wildlife refuge?
23.1 The nature of ecosystems
The nature of ecosystems
•
Biosphere – the regions of the Earth’s waters,
crust, and atmosphere inhabited by living
organisms
•
Ecosystem – a place where organisms interact
between each other and their environment
–
–
Terrestrial: several distinct types based on
temperature and waterfall
Aquatic: freshwater and marine
23.1 The nature of ecosystems
Terrestrial ecosystems
•
Forests – dominated by trees
•
•
•
•
Tropical rain forest
Coniferous forests (taiga)
Temperate deciduous forests
Grasslands – dominated by grass
•
•
•
Tropical grasslands
Temperate grasslands (prairie)
Deserts – characterized by lack of available
moisture
•
•
Tundra
Deserts
23.1 The nature of ecosystems
Terrestrial ecosystems
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
temperate forest
temperate forest
desert
desert
tropical rain forest
tropical grassland (savanna)
tropical rain forest
tropical grassland (savanna)
taiga
temperate grassland (prairie)
temperate grassland (prairie)
autumn tundra
taiga
winter tundra
(temperate, desert, rain forest, prairie): © Corbis RF; (savanna): © Gregory Dimijan/Photo Researchers, Inc.; (taiga): © Brand X Pictures/PunchStock RF;
(autumn tundra): © Joseph Van Os/Getty Images; (winter tundra): © Oxford Scientifi c/Getty Images
23.1 The nature of ecosystems
Aquatic ecosystems
•
Marine
•
•
•
•
•
Seashores
Oceans
Coral reefs
Estuaries
Freshwater
•
•
•
•
Lakes
Ponds
Rivers
Streams
23.1 The nature of ecosystems
Aquatic ecosystems
23.1 The nature of ecosystems
Components of an ecosystem
•
Abiotic components – nonliving environment
•
Biotic components - living components
•
Autotrophs – producers
•
Heterotrophs – consumers
•
•
•
•
•
Herbivores – feed on plant and algae
Carnivores – feed on other animals
Omnivores – eat both plants and animals
Detritus feeders – feed on decomposing organic matter
Niche – the role an organism plays in an ecosystem
such as how it gets its food, what it eats, and how it
interacts with other organisms
23.1 The nature of ecosystems
Biotic components of an ecosystem
23.1 The nature of ecosystems
Energy flow and chemical cycling
•
Energy flow:
•
•
•
•
•
Begins and continues when producers absorb solar energy
Occurs as nutrients pass from one population to another
This energy is converted to heat that dissipates into the
environment
Only a portion of energy is passed to organisms as they
consume one another
Chemical cycling:
•
•
Inorganic nutrients are returned to producers from the
atmosphere or soil
Chemicals recycle within and between ecosystems
23.1 The nature of ecosystems
Energy flow and chemical cycling
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
solar
energy
heat
producers
consumers
inorganic
nutrient pool
heat
energy
heat
decomposers
nutrients
23.1 The nature of ecosystems
Fate of food energy taken
in by a herbivore
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Heat to
environment
growth and reproduction
Energy
to detritus
feeders
© George D. Lepp/Photo Researchers, Inc.
Energy to
carnivores
23.2 Energy flow
Energy flow
•
Food web – describes who eats whom
•
•
•
Trophic levels – composed of all organisms that feed at
a particular link in the food chain
•
•
Grazing food web
Detrital food web
Producers, primary consumers, and secondary consumers
Ecological pyramid – reflects the loss of energy from
one trophic level to another
•
Only about 10% of the energy of one trophic level is available
to the next trophic level
23.2 Energy flow
Food webs
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Autotrophs (Producers)
Herbivores/Omnivores
Carnivores
owls
fruits and
nuts
birds
hawks
leaf-eating
insects
deer
foxes
leaves
chipmunks
rabbits
detritus
skunks
detritus
snakes
detritus
mice
mice
a. grazing food web
fungi and bacteria
(decomposers)
b. Detrital food web
invertebrates
(earthworms)
carnivorous invertebrates
(beetles)
salamanders
shrews
23.2 Energy flow
An example of a food pyramid
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
top carnivores
1.5g/m2
carnivores
11g/m2
herbivores
37g/m2
producers
809g/m2
23.3 Global Biogeochemical cycles
Biogeochemical cycles
•
Biogeochemical cycles are pathways by which
chemicals circulate through an ecosystem including
both living and nonliving components
1.
2.
3.
4.
Water cycle
Carbon cycle
Nitrogen cycle
Phosphorus cycle
•
Reservoir – fossil fuels, minerals in rocks, and
sediment in oceans that contain inorganic nutrients
that are limited in availability
•
Exchange pools – atmosphere, soil, and water that are
ready sources of inorganic nutrients
23.3 Global Biogeochemical cycles
Biogeochemical cycles
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Reservoir
• fossilfuels
• mineral
in rocks
• sediment
in oceans
Exchange
Pool
• atmosphere
• soil
• water
Community
23.3 Global Biogeochemical cycles
Water cycle
•
Water evaporates from the bodies of water,
land, and plants and returns when water falls
on land to enter the ground, surface waters, or
aquifers
•
Human activities that interfere:
•
•
•
Withdraw water from aquifers
Clear vegetation from the land and build structures
that prevent percolation and increase runoff
Add pollutants to water such as sewage and
chemicals
23.3 Global Biogeochemical cycles
Water cycle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
3
transpiration from plants
and evaporation from soil
H2O in Atmosphere
2
precipitation
over land
transport of water vapor by wind
lake
1
evaporation
from ocean
2
precipitation
to ocean
5 fresh water runoff
6
aquifer
Ocean
Ice
4
Groundwaters
23.3 Global Biogeochemical cycles
Carbon cycle
•
CO2 is exchanged between the atmosphere
and living organisms
•
Plants incorporate atmospheric CO2 into
nutrients through photosynthesis that can be
used by living organisms
•
CO2 is returned to the atmosphere through
respiration
23.3 Global Biogeochemical cycles
Carbon cycle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
7
combustion
1
CO2 in Atmosphere
photosynthesis
2
4
destruction
of vegetation
respiration
3
decay
7
Land plants
diffusion
Ocean
bicarbonate (HCO3–)
5
Soils
6
coal
natural gas
oil
dead
organisms
and animal
waste
23.3 Global Biogeochemical cycles
Carbon cycle
•
Human activities that interfere:
•
Burning of fossil fuels and the destruction of forests
are depositing CO2 to the atmosphere faster than it
is being removed
•
CO2 and other gases (N2O and CH4) are being
emitted due to human activities
•
These gases are called greenhouse gases because
they trap heat that contributes to global warming
23.3 Global Biogeochemical cycles
Greenhouse gases and global warming
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
solar radiation
solar radiation
solar radiation
reflected
reflected
clouds
green house gases
in atmosphere
reradiated
Greenhouse
effect
absorbed
Solar radiation that
passes through
the atmosphere
warms the Earth’s
surface.
Clouds, which contain
water vapor, absorb
infrared rays (heat) from the
earth’s surface and warm
the surface by downward
reradiation of a portion of
these rays.
Green house gases, including carbon
dioxide and methane, also cause the
atmosphere to absorb and reradiate infrared
rays toward the surface of the Earth. As the
concentration of green house gases
increases, the temperature of the Earth is
expected to increase also.
23.3 Global Biogeochemical cycles
Nitrogen cycle
•
78% of the atmosphere is nitrogen gas but it is
not in a usable form by plants
•
Nitrogen-fixing bacteria convert nitrogen gas to
ammonium that can be used by plants
•
Nitrifying bacteria convert ammonium to nitrate
•
Bacteria convert nitrate back to nitrogen gas
through a process called dentrification
Fig. 23.12
23.3 Global Biogeochemical cycles
Nitrogen cycle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
N2 in Atmosphere
N2 fixation
1
2
7
8
1
N2 fixation
nitrogen-fixing
bacteria in nodules
And soil
denitrification
runoff
8
human
activities
plants
2
nitrification
dead organisms
and animal waste
denitrifying bacteria
6
decomposers
NO3–
cyanobacteria
Biotic
Community
3
Biotic
Community
NH4+
denitrification
7
NH4+
nitrifying
bacteria
4
NO2
decomposers
NO2
5
denitrifying
bacteria
phytoplankton
23.3 Global Biogeochemical cycles
Nitrogen cycle
•
Human activities interfere:
•
We add nitrogen fertilizers that run off into lakes and
streams that cause major fish kills by eutrophication
•
Burning of fossil fuels
-
-
puts nitrogen oxides and sulfur dioxide into the atmosphere
where they combine with water vapor to form acids that
return to earth as acid deposition
Result in nitrogen oxides and hydrocarbons that react with
one another to produce smog
23.3 Global Biogeochemical cycles
Nitrogen cycle
23.3 Global Biogeochemical cycles
Phosphorus cycle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
•
•
Phosphate ions
become
available to
living organisms
by the slow
weathering of
rocks
Phosphate is a
limiting nutrient
in ecosystems
minable rock
weathering
phosphate mining
2
geologic uplift
sewage treatment
plants
8
fertilizer
plants
runoff 8
4
8
3
animals and
animal wastes
Biotic
Community
phosphate
in soil
phosphate
in solution
6
biota
5
1
decomposers
detritus
7
sediments
23.3 Global Biogeochemical cycles
Phosphorus cycle
•
Human activities interfere:
•
Runoff of phosphate due to fertilizer and discharge
from sewage treatment plants results in
eutrophication
•
Sources of pollution:
-
Point source – specific sources
Nonpoint sources – runoff from land
23.3 Global Biogeochemical cycles
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Sources of Water Pollution
Sources of pollution
Leading to Cultural Eutrophication
Oxygen-demanding
waste
Biodegradable organic compounds
(e.g., sewage, wastes from food-processing
plants, paper mills, and tanneries)
Plant nutrients
Nitrates and phosphates from detergents,
fertilizers, and sewage treatment plants
Sediments
Enriched soil in water due to soil erosion
Thermal discharges
Heated water from power plants
Health Hazards
Disease-causing agents Bacteria and viruses from sewage and
barnyard waste (causing, for example,
cholera, food poisoning, and hepatitis)
Synthetic organic
compounds
Pesticides, industrial chemicals
(e.g., PCBs)
Inorganic chemicals
and minerals
Acids from mines and air pollution;
dissolved salts; heavy metals
(e.g., mercury) from industry
Radiation
Radioactive substances from nuclear
power plants, medical and research facilities
acidic water
from mines
sediments
city
crop dusting
industrial wastes
barnyard wastes
biomedical
wastes
suburban
development
fertilizer runoff
sewage
treatment plant
oil pollution
nuclear reactor
23.3 Global Biogeochemical cycles
Science focus: ozone shield depletion
•
Ozone shield – a layer of ozone in the stratosphere
that absorbs UV rays preventing them from reaching
the earth
•
Causes of depletion:
–
Chlorine atoms primarily from chlorofluorocarbons(CFCs)
•
•
•
•
Freon used as a coolant
Cleaning agents
Agents used to make Styrofoam
Concerns about loss of ozone:
–
–
–
–
Increases mutations leading to skin cancer
Adversely affects the immune system
Impairs crop and tree growth
Can kill off algae and krill that sustain oceanic life
23.3 Global Biogeochemical cycles
Science focus: ozone shield depletion
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ozone (Dobson Units)
110
220
330
Courtesy NASA
440
550