Circulatory and Gas Exchange Systems

1
Ecosystem Ecology
Chapter 54
2
Ecosystem all the organisms living in a
community, plus all the abiotic factors with
which they interact
From a small closed system to the biosphere
3
Two principal ecosystem processes energy flow
chemical cycling
Tertiary consumers
Microorganisms and other detritivores
Secondary consumers
Primary consumers
Detritus
Primary producers
Fig. 54.2
Heat
Key
Chemical cycling
Sun
Energy flow
Energy flows through an ecosystem (energy from
the sun ultimately dissipates into space as heat)
4
Two principal ecosystem processes energy flow
chemical cycling
Tertiary consumers
Microorganisms and other detritivores
Secondary consumers
Primary consumers
Detritus
Primary producers
Fig. 54.2
Heat
Key
Chemical cycling
Sun
Energy flow
Chemical elements are continually recycled
5
Two principal ecosystem processes energy flow
chemical cycling
Tertiary consumers
Microorganisms and other detritivores
Secondary consumers
Primary consumers
Detritus
Primary producers
Fig. 54.2
Heat
Key
Chemical cycling
Sun
Energy flow
Physical laws govern these processes
6
Two principal ecosystem processes energy flow
chemical cycling
Tertiary consumers
Microorganisms and other detritivores
Secondary consumers
Primary consumers
Detritus
Primary producers
Fig. 54.2
Heat
Key
Chemical cycling
Sun
Energy flow
1st Law of Thermodynamics Conservation of Energy
7
Two principal ecosystem processes energy flow
chemical cycling
Tertiary consumers
Microorganisms and other detritivores
Secondary consumers
Primary consumers
Detritus
Primary producers
Fig. 54.2
Heat
Key
Chemical cycling
Sun
Energy flow
2nd Law of Thermodynamics Energy transformation
is inefficient (between trophic levels)
8
Two principal ecosystem processes energy flow
chemical cycling
Tertiary consumers
Microorganisms and other detritivores
Secondary consumers
Primary consumers
Detritus
Primary producers
Fig. 54.2
Heat
Key
Chemical cycling
Sun
Energy flow
Primary producers take elements in inorganic
molecules and incorporate them into organic
molecules
9
Two principal ecosystem processes energy flow
chemical cycling
Tertiary consumers
Microorganisms and other detritivores
Secondary consumers
Primary consumers
Detritus
Primary producers
Fig. 54.2
Heat
Key
Chemical cycling
Sun
Energy flow
Additional organic molecules are produced at
other trophic levels
10
Two principal ecosystem processes energy flow
chemical cycling
Tertiary consumers
Microorganisms and other detritivores
Secondary consumers
Primary consumers
Detritus
Primary producers
Fig. 54.2
Heat
Key
Chemical cycling
Sun
Energy flow
Organic molecules are broken down into inorganic
molecules by metabolism and decomposition of
detritus
11
Energy budgets
Gross primary production (GPP) ? the amount of
light energy converted to chemical energy per
unit time (by primary producers through
photosynthesis)
Net primary production (NPP) ? GPP minus energy
used by primary producers for respiration NPP
GPP - R
12
Energy budgets
125
Open ocean
24.4
65.0
360
Continental shelf
5.2
5.6
Estuary
1,500
0.3
1.2
Algal beds and reefs
0.1
2,500
0.9
Upwelling zones
0.1
500
0.1
Extreme desert, rock, sand, ice
3.0
4.7
0.04
0.9
Desert and semidesert scrub
90
3.5
Tropical rain forest
3.3
2,200
22
2.9
Savanna
900
7.9
9.1
Cultivated land
2.7
600
Boreal forest (taiga)
9.6
2.4
800
1.8
Temperate grassland
600
5.4
Woodland and shrubland
700
1.7
3.5
Tundra
1.6
140
0.6
Tropical seasonal forest
1,600
7.1
1.5
Temperate deciduous forest
1,200
1.3
4.9
1,300
Temperate evergreen forest
1.0
3.8
0.4
Swamp and marsh
2,000
2.3
Lake and stream
0.4
250
0.3
0
10
20
30
40
50
60
0
500
1,000
1,500
2,000
2,500
0
5
10
15
20
25
Key
(a) Percentage of Earths surface area
(b) Average net primary production (g/m2/yr)
(c) Percentage of Earths net primary
production
Marine
Figure 54.4
Terrestrial
Freshwater (on continents)
Different ecosystems vary in overall size (Fig.
a), NPP (Fig. b), and their contributions to
total NPP on Earth (Fig. c)
13
Energy budgets
125
Open ocean
24.4
65.0
360
Continental shelf
5.2
5.6
Estuary
1,500
0.3
1.2
Algal beds and reefs
0.1
2,500
0.9
Upwelling zones
0.1
500
0.1
Extreme desert, rock, sand, ice
3.0
4.7
0.04
0.9
Desert and semidesert scrub
90
3.5
Tropical rain forest
3.3
2,200
22
2.9
Savanna
900
7.9
9.1
Cultivated land
2.7
600
Boreal forest (taiga)
9.6
2.4
800
1.8
Temperate grassland
600
5.4
Woodland and shrubland
700
1.7
3.5
Tundra
1.6
140
0.6
Tropical seasonal forest
1,600
7.1
1.5
Temperate deciduous forest
1,200
1.3
4.9
1,300
Temperate evergreen forest
1.0
3.8
0.4
Swamp and marsh
2,000
2.3
Lake and stream
0.4
250
0.3
0
10
20
30
40
50
60
0
500
1,000
1,500
2,000
2,500
0
5
10
15
20
25
Key
(a) Percentage of Earths surface area
(b) Average net primary production (g/m2/yr)
(c) Percentage of Earths net primary
production
Marine
Figure 54.4
Terrestrial
Freshwater (on continents)
Terrestrial ecosystems contribute about 2/3 and
marine ecosystems about 1/3 of global NPP
14
Energy budgets
Resources limit primary production (just as they
limit population growth)
Resources light, water, nutrients
For example, large-scale manipulations often
demonstrate N or P limitation of NPP
Figure 54.7
15
Energy budgets
For example, actual evapotranspiration correlates
well with NPP across biomes
Figure 54.8
16
Energy budgets
Actual evapotranspiration is the amount of water
transpired plus evaporated (a function of water
availability and solar energy)
Figure 54.8
17
Energy budgets
Secondary production is the amount of chemical
energy in consumers food converted to consumer
biomass
Some energy at each trophic level remains
unassimilated (uneaten not shown in the fig.)
Plant material eaten by caterpillar
200 J
67 J
Cellular respiration
100 J
Feces
33 J
Figure 54.10
Growth (new biomass)
18
Energy budgets
Secondary production is the amount of chemical
energy in consumers food converted to consumer
biomass
Some assimilated energy is passed in waste, some
is used in respiration, and the rest is net
secondary production
Plant material eaten by caterpillar
200 J
In this example, lt17 is used for secondary
production
67 J
Cellular respiration
100 J
Feces
33 J
Figure 54.10
Growth (new biomass)
19
Energy budgets
Trophic efficiency is the percentage of
production transferred from one trophic level to
another
Primary producers only convert 1 of sunlight
Other trophic levels 10 (5 to 20)
Figure 54.11
20
Energy budgets
Pyramid of net production
Primary producers only convert 1 of sunlight
Other trophic levels 10 (5 to 20)
Figure 54.11
21
Energy budgets
Pyramid of biomass
The standing crop at each trophic level
Usually narrows from the base upwards
Dry weight (g/m2)
Trophic level
Tertiary consumers
1.5
Secondary consumers
11
37
Primary consumers
Primary producers
809
Figure 54.12
22
Energy budgets
Pyramid of biomass
The standing crop at each trophic level
But sometimes increases upwards if primary
producers turn over rapidly
Dry weight (g/m2)
Trophic level
Primary consumers (zooplankton)
21
Primary producers (phytoplankton)
4
Figure 54.12
23
Energy budgets
Pyramid of numbers
Predators tend to be larger than prey, so
pyramids of numbers nearly always narrow upwards
E.g., field in Michigan
Figure 54.13
24
Energy budgets
Pyramid of numbers
For a given amount of grain, carnivorous humans
fair worse than vegetarians!
Figure 54.13
25
Biogeochemical cycles
Earth is nearly a closed system with respect to
amounts of elements (with the exception of minor
additions and losses, e.g., meteorites)
Assimilation, photosynthesis
Figure 54.16
26
Biogeochemical cycles
The general biogeochemical cycle of an element
(see fig.)
Elements cycle among pools that vary in whether
they are (1) incorporated in organic vs.
inorganic molecules, or (2) available vs.
unavailable to organisms
Assimilation, photosynthesis
Figure 54.16
27
THE WATER CYCLE
Major reservoir is the ocean (which contains
about 97 of Earths water)
Solar energy
Transport over land
Net movement of water vapor by wind
Precipitation over land
Evaporation from ocean
Key processes include evaporation, transpiration,
condensation in clouds, and precipitation
Precipitation over ocean
Evapotranspiration from land
Percolation through soil
Runoff and groundwater
Figure 54.17
28
THE CARBON CYCLE
Major reservoirs with fast turnover include
fossil fuels, soils, dissolved carbon compounds
in the oceans, biomass, CO2
CO2 in atmosphere
Photosynthesis
Cellular respiration
Burning of fossil fuels and wood
The largest pool is sedimentary rock, but
turnover is very slow
Higher-level consumers
Primary consumers
Carbon compounds in water
Detritus
Decomposition
Figure 54.17
29
THE CARBON CYCLE
Key processes are photosynthesis, respiration,
burning of fossil fuels, volcanoes
CO2 in atmosphere
Photosynthesis
Cellular respiration
Burning of fossil fuels and wood
Higher-level consumers
Primary consumers
Carbon compounds in water
Detritus
Decomposition
Figure 54.17
30
THE PHOSPHORUS CYCLE
Major reservoirs are sedimentary rocks, soils,
oceans, and biomass
Rain
Weathering of rocks
Geologic uplift
Runoff
Key processes include weathering of rocks and
decomposition little cycling in the atmosphere
Consumption
Plant uptake of PO43?
Sedimentation
Soil
Leaching
Decomposition
Figure 54.17
31
THE NITROGEN CYCLE
Major reservoir is the atmosphere (which is about
80 N2)
N2 in atmosphere
Key process for N to enter an ecosystem is
fixation, the conversion of N2 by bacteria (or
lightning) to forms usable by plants
Decomposers
Assimilation
Denitrifying bacteria
NO3?
Nitrogen-fixing bacteria in root nodules of
legumes
Nitrifying bacteria
Ammonification
Nitrification
NH4
NO2 ?
NH3
Nitrifying bacteria
Nitrogen-fixing soil bacteria
Figure 54.17
32
Humans have dramatically altered biogeochemical
cycles and ecosystems
The Hubbard Brook, NH experiment demonstrates the
importance of forests for nutrient cycling
Whole watersheds were experimentally deforested
or not
Figure 54.19
33
Humans have dramatically altered biogeochemical
cycles and ecosystems
The Hubbard Brook, NH experiment demonstrates the
importance of forests for nutrient cycling
Weirs measured nutrient loss from watersheds
Figure 54.19
34
Humans have dramatically altered biogeochemical
cycles and ecosystems
The Hubbard Brook, NH experiment demonstrates the
importance of forests for nutrient cycling
80.0
Deforested
60.0
40.0
20.0
Nitrate concentration in runoff (mg/L)
Completion of tree cutting
4.0
Control
3.0
2.0
1.0
0
1967
1965
1966
1968
Deforested watersheds lost nutrients at
prodigious rates
Figure 54.19
35
Humans have dramatically altered biogeochemical
cycles and ecosystems
Oxides of sulfur and nitrogen from burning of
fossil fuels have formed sulfuric and nitric
acid, which have acidified soils
Figure 54.22
36
Humans have dramatically altered biogeochemical
cycles and ecosystems
Anthropogenic CO2 is the direct cause of global
warming and various other manifestations of
climate change
Figure 54.24