Transcript Primary producers

Chapter 55
Ecosystems
PowerPoint® Lecture Presentations for
Biology
Eighth Edition
Neil Campbell and Jane Reece
•Energy flows through
ecosystems while
matter cycles within
them. These are the 2
processes in
ecosystems.
Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 55-1
•1st law of thermodynamics - energy cannot be created or
destroyed, only transformed
•2nd law of thermodynamics - every exchange of energy
increases the entropy of the universe
•Law of conservation of mass - matter cannot be created or
destroyed
•Ecosystems are open systems, absorbing energy and mass and
releasing heat and waste products
Fig. 55-4
Tertiary consumers
Microorganisms
and other
detritivores
Detritus
Secondary
consumers
Primary consumers
Primary producers
Heat
Key
Chemical cycling
Energy flow
Sun
Fig. 55-3
•Detritivores, or
decomposers, are
consumers that derive
their energy from
detritus, nonliving
organic matter
•Decomposition connects
all trophic levels
•Decomposition rate is
controlled by
temperature, moisture,
and nutrient availability
(low = rapid decomp)
Concept 55.2: Energy and other limiting factors
control primary production in ecosystems
• Primary production - amount of light energy
converted to chemical energy by autotrophs
during a given time period
• Total primary = gross primary production
(GPP)
• Net primary production (NPP) - GPP minus
energy used by primary producers for
respiration
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Nutrient Limitation
• Limiting nutrient - element that must be added
for production to increase in an area
– N2 and P most often limit marine production
• In terrestrial ecosystems, temperature and
moisture affect primary production on a large scale
• Actual evapotranspiration - water annually
transpired by plants and evaporated from a
landscape
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 55-8
Net primary production (g/m2··yr)
3,000
Tropical forest
2,000
Temperate forest
1,000
Mountain coniferous forest
Desert
shrubland
Temperate grassland
Arctic tundra
0
0
500
1,500
1,000
Actual evapotranspiration (mm H2O/yr)
Fig. 55-9
Secondary
production amount of
chemical
energy in food
converted to
new biomass
during a given
period of time
Production
efficiency fraction of
energy stored
in food that is
not used for
respiration
Plant material
eaten by caterpillar
200 J
67 J
Feces
100 J
33 J
Growth (new biomass)
Cellular
respiration
Fig. 55-10
Tertiary
consumers
Secondary
consumers
10 J
100 J
Primary
consumers
1,000 J
Primary
producers
10,000 J
Trophic
efficiency –
% of production
transferred from
one trophic level
to the next
1,000,000 J of sunlight
Fig. 55-11
Trophic level
Tertiary consumers
Secondary consumers
Primary consumers
Primary producers
Dry mass
(g/m2)
1.5
11
37
809
(a) Most ecosystems (data from a Florida bog)
Trophic level
Primary consumers (zooplankton)
Primary producers (phytoplankton)
Dry mass
(g/m2)
21
4
(b) Some aquatic ecosystems (data from the English Channel)
Turnover time - ratio of standing crop biomass to production
Most terrestrial ecosystems have large standing crops
despite the large numbers of herbivores
Green world hypothesis proposes several factors that keep herbivores in
check:
Plant defenses
Limited availability of essential nutrients
Abiotic factors
Intraspecific competition
Interspecific interactions
Biogeochemical Cycles
• Gaseous C, O2, S, and N2 occur in the atmosphere and
cycle globally
• Less mobile elements such as P, K, and Ca cycle on a more
local level
• Cycling of H2O, C, N, and K, we focus on 4 factors:
– Each chemical’s biological importance
– Forms in which each chemical is available or used by
organisms
– Major reservoirs for each chemical
– Key processes driving movement of each chemical
through its cycle
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 55-13
Reservoir A
Reservoir B
Organic
materials
available
as nutrients
Organic
materials
unavailable
as nutrients
Fossilization
Living
organisms,
detritus
Assimilation,
photosynthesis
Coal, oil,
peat
Respiration,
decomposition,
excretion
Burning
of fossil fuels
Reservoir C
Reservoir D
Inorganic
materials
available
as nutrients
Inorganic
materials
unavailable
as nutrients
Atmosphere,
soil, water
Weathering,
erosion
Formation of
sedimentary rock
Minerals
in rocks
Fig. 55-14a
97% of the
biosphere’s
water is
contained in
the oceans,
2% is in
glaciers and
polar ice Precipitation
over ocean
caps, and
1% is in
lakes, rivers,
and
groundwater
Water Cycle
Transport
over land
Solar energy
Net movement of
water vapor by wind
Evaporation
from ocean
Precipitation
over land
Evapotranspiration
from land
Percolation
through
soil
Runoff and
groundwater
Fig. 55-14b
Carbon Cycle
CO2 in atmosphere
Photosynthesis
Photosynthesis
Cellular
respiration
Burning of
fossil fuels Phytoand wood plankton
Higher-level
consumers
Primary
consumers
Carbon compounds
in water
Detritus
Decomposition
Fig. 55-14c
Nitrogen Cycle
N2 in atmosphere
Assimilation
NO3–
Nitrogen-fixing
bacteria
Decomposers
Ammonification
NH3
Nitrogen-fixing
soil bacteria
Nitrification
NH4+
NO2–
Nitrifying
bacteria
Denitrifying
bacteria
Nitrifying
bacteria
Phosphorus
Cycle
Major
constituent of
nucleic acids,
phospholipids,
and ATP
Phosphate
(PO43–) most
important
inorganic
Precipitation
Geologic
uplift
Weathering
of rocks
Runoff
Consumption
Decomposition
Plant
uptake
of PO43–
Plankton Dissolved PO43–
Uptake
Sedimentation
Soil
Leaching
Fig. 55-17
Why is this picture important?
Critical load for a nutrient is the amount that plants can
absorb without damaging the ecosystem
Winter
Summer
Remaining nutrients can contaminate groundwater as well as
freshwater and marine ecosystems
Sewage runoff causes cultural eutrophication, excessive algal
growth that can greatly harm freshwater ecosystems
Acid Precipitation
• Combustion of fossil fuels is the main cause of acid
precipitation
• North American and European ecosystems downwind
from industrial regions have been damaged by rain
and snow containing nitric and sulfuric acid
• Acid precipitation changes soil pH and causes
leaching of calcium and other nutrients
• Environmental regulations and new technologies have
allowed many developed countries to reduce sulfur
dioxide emissions
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 55-19
4.5
4.4
4.3
4.2
4.1
4.0
1960 1965 1970 1975 1980 1985 1990 1995 2000
Year
Fig. 55-20
Biological
magnification
- concentrates
toxins at
higher trophic
levels, where
biomass is
lower
Herring
gull eggs
124 ppm
Lake trout
4.83 ppm
Smelt
1.04 ppm
Zooplankton
0.123 ppm
Phytoplankton
0.025 ppm
Fig. 55-21
390
380
14.9
Burning fossil fuels and other
human activities have
increased the conc. of
atmospheric CO2
370
14.8
14.7
14.6
Temperature
14.5
360
14.4
14.3
350
14.2
340
14.1
CO2
330
14.0
CO2, water vapor, and other
greenhouse gases reflect
infrared radiation back toward
Earth; this is the greenhouse
effect
320
310
300
1960
1965
1970
1975
1980 1985
Year
1990
1995
2000
2005
13.9
13.8
13.7
13.6
Fig. 55-23
Life on Earth is protected from
damaging effects of UV
radiation by a protective layer
of ozone molecules in the
atmosphere
Ozone layer thickness (Dobsons)
350
300
250
200
100
Satellite studies
suggest that the
ozone layer has
been gradually
thinning since
1975
0
1955 ’60
’65
’70
’75
’80 ’85
Year
’90
’95 2000 ’05
Destruction of atmospheric ozone probably results from chlorinereleasing pollutants such as CFCs produced by human activity
Chlorine atom
O2
Chlorine O3
ClO
O2
ClO
Cl2O2
Sunlight
Fig. 55-25
Scientists first described an “ozone hole” over Antarctica in 1985;
it has increased in size as ozone depletion has increased
(a) September 1979
(b) September 2006
Ozone depletion causes DNA damage in plants and poorer
phytoplankton growth