BIOS 5445: Human Ecology
Dr. Stephen Malcolm, Department of Biological Sciences
•  Week 11.
Survivorship:
energy flow
–  Lecture
summary:
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Energy.
Productivity.
Web flow.
Human energy
flow:
–  Examples
http://www.ftexploring.com/me/me2.html
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 1
2. Matter and energy:
•  All organisms require matter for construction,
and energy for activity, at individual,
population and community levels of
organization.
•  Communities interact with the abiotic
environment as ecosystems which include:
–  primary producers, decomposers and detritivores,
a pool of dead organic matter, herbivores,
carnivores and parasites, plus the physicochemical
environment that provides living conditions and acts
both as a source and a sink for energy and matter.
•  Begon et al. (2006).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 2
3. Productivity:
•  The primary productivity of a community is:
–  The rate at which biomass is produced per
unit area by plants (primary producers) as
energy (J·m-2·day-1) or dry organic matter
(kg·ha-1·year-1).
•  Gross primary productivity (GPP)
–  Total fixation of energy by photosynthesis
•  Net primary productivity (NPP)
–  GPP - energy lost to respiration
»  = actual rate of biomass accumulation available for
consumption by heterotrophs.
•  Secondary productivity
–  Rate of biomass production by heterotrophs.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 3
4. Net primary productivity:
•  Global terrestrial NPP:
–  110 - 120 x 109 tonnes dry weight per year.
•  Global marine NPP (Fig. 18.1, Table 18.1):
–  50 - 60 x 109 tonnes per year:
•  despite being 67% of the earth's surface.
•  Productivity (P) and biomass (B):
–  (Fig. 18.5):
–  P:B ratios (kg/year/kg biomass) average:
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Dr. S. Malcolm
0.042 for forests.
0.29 for other terrestrial systems.
17 for aquatic communities.
Ratios also change with successional shifts (Fig. 18.6).
BIOS 5445: Human Ecology
Week 11: Slide - 4
5. Community trophic structure:
•  Energy moves through communities via trophic
(feeding) interactions.
•  Primary productivity generates secondary
productivity in heterotrophic consumers
once they consume autotrophs with a
measurable efficiency:
–  The slope of Fig. 18.17 at about 0.1.
•  Generates the classical view of a broad-based
productivity pyramid or biomass pyramid:
–  After Elton (1927) and later Lindemann (1942).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 5
6. Community trophic structure:
•  Basic trophic structure of communities:
–  (Figs 18.18 & 18.19).
•  Energy flow through different components of a
grassland community (Fig. 18.22).
•  Predicted vs observed values of productivity:
–  (Fig. 18.23).
•  Energy flow & nutrient cycling links between
decomposer & grazer systems & return of
free inorganic nutrients released by
decomposers from dead organic matter
(DOM) back to net primary production (NPP):
–  (Fig. 19.1).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 6
7. NPP and global climate change
•  Climate models predict that increased
greenhouse gases will lead to an
increase in temperature of 1.5-4.5°C.
•  Altered CO2, temperature, cloud cover
and rainfall will dramatically change
the NPP of earth's communities:
–  Table 18.6.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 7
8. Flux of matter:
•  If plants, and their consumers, were not
eventually decomposed, the supply of
nutrients would become exhausted and life
on earth would cease.
•  So the matter cycling (fueled by energy)
of Fig. 19.1 is essential.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 8
9. The Hubbard Brook experiments:
•  How important is nutrient cycling within a
terrestrial community in relation to the
through-put of nutrients?
•  The Hubbard Brook experiment in the temperate
deciduous forest of the White Mountains in
New Hampshire is the best test of this
question:
–  6 small catchments with input and output measured:
•  (Table 19.2).
–  Most nutrients were held in biomass:
•  Like N2 in Fig. 19.5.
–  But sulfur was released in excess of input because it
was a major pollutant in the area (acid rain).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 9
10. The Hubbard Brook experiments:
•  Experimentally, one catchment was deforested:
–  The rate of nutrient loss rose x13 in
comparison with a control catchment.
–  Two reasons for the lost nutrients:
•  (1) Through increased water flow (less water held
by trees) - see Fig. 19.4.
•  (2) Within-system nutrient cycling was lost by
uncoupling the decomposition process from
the plant-uptake process:
–  Nutrients made available by decomposition were lost to
leaching in the increased stream flow (Fig. 19.6).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 10
11. Examples - Dobe San foraging
system (Fig. 14-3):
animal
source
storage
green plant
heat sink
work gate
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 11
12. Examples - Ngisonyoka Turkana
pastoral system (Fig. 14-6):
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 12
13. Examples - Tsembaga Maring
horticultural system (Fig. 14-10):
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 13
14. Daily energy consumption in different
societies (kcal/person/day)(Fig. 14-11):
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 14
15.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 15
16.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 16
Figure 18.1:
Distribution of
global terrestrial
and marine net
primary
productivity
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 17
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 18
Figure 18.5: Relationship between average net
primary productivity and average standing crop
biomass for communities in Table 18.1
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 19
Figure 18.6: Change in net primary productivity (P),
standing crop biomass (B) and P:B ratio during
forest succession on Long Island
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 20
Figure 18.17: Secondary productivity plotted
against primary productivity in three communities.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 21
Figure 18.18:
Energy flow
through a trophic
compartment.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 22
Figure 18.19: Model of trophic structure and
energy flow for a terrestrial community.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 23
Figure 18.22: Patterns of energy flow through the
different trophic compartments of Fig. 18.19.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 24
Figure 18.23: Predicted heterotroph productivity
plotted against observed productivity in a
range of communities.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 25
Figure 19.1: Energy flow (pink) and nutrient cycling
of organic matter (red) and inorganic matter (white).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 26
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 27
Table 19.2:
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 28
Figure 19.5: Annual nitrogen budget for control
forest at Hubbard Brook (kg N2/ha).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 29
Figure 19.4: Annual loss of major nutrients
in streamflow.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 30
Figure 19.6:
Concentrations of ions in
stream water from
control and deforested
watersheds at Hubbard
Brook.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 11: Slide - 31
32. References:
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Begon, M., C.R. Townsend, & J.L. Harper. 2006. Ecology: From
individuals to ecosystems. 4th edition. Blackwell Science, Oxford, 738
pp.
Elton, C. 1927. Animal ecology. Sidgwick & Jackson, London.
Kormondy, E.J., & D.E. Brown. 1998. Fundamentals of Human Ecology.
Prentice Hall.
Lindemann, R.L. 1942. The trophic-dynamic aspect of ecology. Ecology
23: 399-418.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 32