Elements of Ecology

1. CHAPTERS 21-23
PRESENTED BY: LEANDRO MICHAEL C. DE LOS SANTOS, JR.

2. CHAPTER 21
Ecosystem Energetics

3. 1. Describe the effects of temperature,
moisture, length of photosynthetic period,
and nutrient availability on net primary
productivity in terrestrial ecosystems.

4. Terms to define:
Net Primary Productivity (NPP)- is the rate of
energy storage as organic matter after respiration
Gross Primary Productivity (GPP)- total rate of
photosynthesis or energy assimilated by the
autothrophs

5. Factors limiting primary productivity in terrestrial
ecosystems
 Temperature
 Precipitation
 Light
 Nutrients

8. Global map of primary productivity

9. To summarize:
Temperature + Precipitation = NPP
Temperature + Precipitation = NPP
Temperature + Precipitation = NPP
Temperature = Length of Photosynthesis = NPP
Nutrients = Nutrient uptake,
photosynthesis & plant growth =
NPP

10. 2. Explain why primary
productivity is typically higher in
coastal areas of the ocean than far
from shore in the open ocean.

12. 3. Explain the difference between
primary production and secondary
production. How is secondary
production affected by primary
production?

13. Primary Production- production by
green plants over time
Secondary Production- production by
consumer organisms over time which
include consumption of energy from
the produces which is then used for
metabolic activities

14. Primary productivity
limits secondary
productivity

15. 4. What are the two main food chains
of ecosystems? Which is more
dominant in terrestrial ecosystems and
why?

16. Grazing food chain- the source of energy is living
plant biomass or net primary production
ex. Cattle grazing on pastureland, insect feeding
on leaves, zooplankton feeding on phytoplankton
Detrital food chain- source of energy is dead
organic matter or detritus
ex. snails, bettles, millipeds, earthworms, fungi &
bacteria

17. 2 Food chains

18. Detrital food chain is the most common food
chain in all ecosystems since most ungrazed or
unconsumed energy is returned to the soil as
dead material.
In a yellow poplar forest
maintenance & respiration 50%
new tissue 13%
consumed by herbivores 2%
Detrital food chain 35%

19. 5. Explain why energy is lost as it is
transferred from one trophic level to
another. What are the effects of energy
loss on the biomass of different trophic
levels?

20. Trophic efficiency- ratio of productivity in a given
trophic level to the trophic level it feeds on

22. 6. How do humans affect net primary
productivity? Does the affluence of a
society affect how humans appropriate
net primary productivity?

23. • Human species consume a vast amount of
Earth’s resources
• In a study conducted by Vitousek, et. al they
used 3 approaches to estimate human NPP
appropriation:
 low estimate- food, fuel, fiber, timber
 intermediate estimate- productivity of
lands devoted to human activities
 high estimate- conversion of lands to
cities, forests to pastures or overgrazing
or excessive erosion

24. Both population and per capita consumption
interact to determine the human ecological
impact on regional scale.
Affluence also affect net primary productivity
among humans. Developed countries have
double HANPP compared to developing nations

25. CHAPTER 22
Decomposition and Nutrient Cycling

26. 1. Describe the movement of an atom of
nitrogen from the leaf of a plant,
through the process of decomposition,
and back into the root of another plant.

29. 2. Describe three different processes
that are important for decomposition.
Explain which organisms are important
for each of the processes.

30. Decomposition processes:
1. Leaching- dissolving and washing of
nutrients out of soil, litter and organic matter
ex. bacteria and fungi
2. Fragmentation- disintegration of organic
matter by invertebrate detritivores such as
protozoans, nematodes, millipedes, etc.
3. Ingestion & excretion of waste products-
heterotrophs function as decomposers by
digesting food, break down organic matter,

31. 3. Discuss the effects of temperature,
humidity, and oxygen availability on
the rate of decomposition.

32. 2 things related to decomposition rate:
 the quality of plant litter as a substrate for
microorganisms and soil fauna active in the
decomposition process
 Features of the physical environment that
directly influence decomposer populations
like soil properties and climate

35. 4. Explain how the "quality" of plant-
derived organic matter changes during
the course of decomposition.

37. 5. Define mineralization and immobilization,
and discuss the differences between them

38. Mineralization- microbial breakdown of humus and
other organic matter in soil to inorganic matter esp
into its ionic form such as ammonium, sulfate and
phosphate
Immobilization- conversion of an element from
inorganic to organic form in microbial or plant tissue,
rendering the nutrient unavailable to other organisms

40. 6. Describe two major differences between
decomposition in terrestrial environments
and
decomposition in aquatic environments.

41. Terrestrial Decomposition
 decomposition is a soil process
 involves two size-based animal groups; the
macrofauna and the microfauna
 primary production and decomposition is linked
by vegetation
(Source: http://ww2.tnstate.edu)

42. Aquatic Decomposition
 macrofauna found in freshwater is similar to
those found in soils except for millipedes, in
marine, there are no insects instead there are
polychaetes and many crustaceans
 in aquatic systems, the photic zone may be
separated from the benthos (where most
decomposition goes on)
 nutrients are only mixed into the photic zone
when thermocline breaks down and Turnover
of the body of water can occur
(Source: http://ww2.tnstate.edu)

44. 7. Describe one major difference between
nutrient cycling in a river and nutrient
cycling in a lake

45. Nutrient Cycling in Lakes

46. Nutrient Cycling in Rivers (Nutrient Spiraling)

47. 8. Describe the process of upwelling in
the ocean and how it relates to fisheries

48. What is upwelling?
Winds blowing across the
ocean surface push water
away. Water then rises up
from beneath the surface to
replace the water that was
pushed away
Source: www.oceanservice.noaa.gov

49. Water that rises to the surface as a result of
upwelling is rich in nutrients. These nutrients
“fertilize” surface waters and therefore are good
fishing grounds due too high biological
productivity

50. 9. Describe how you might go about
measuring the rate of decomposition of leaf
litter in the upper layer of a forest soil.

51. CHAPTER 23
Biogeochemical Cycles

52. 1. Explain the difference between the
two basic types of biogeochemical
cycles, using specific examples of each.

53. What is biogeochemical cycle?
•any of the natural circulation pathways of the
essential elements of living matter. These elements
in various forms flow from the nonliving (abiotic)
to the living (biotic) components of the biosphere
and back to the nonliving again

54. 2 Major types of biogeochemical cycles:
1. gaseous- main pool of nutrients are the
atmosphere and oceans (via evaporation)ex.
carbon, nitrogen, oxgen, carbon and water
2. sedimentary- main pool of nutrients are the
rocks, soil and minerals (Earth’s crust) ex. iron,
phosphorous, sulfur & other earthbound
elements

55. 2. Describe three ways that nutrients
can be lost from an ecosystem

56. 3 ways of nutrient loss in the ecosystem:
1. Export of nutrients
 carbon being exported to the atmosphere via
respiration
 microbial and plant processes being transformed
to nutrients in a gaseous phase
 Organic matter being carried from the ecosystem
through surface flow of water in streams & rivers

57. 3 ways of nutrient loss in the ecosystem:
2. Harvesting
 Biomass harvest such as in farming and logging
3. Fire
 Kills vegetation and converts some biomass to soil
organic matter to ash
 If not taken up by vegetation during recovery,
nutrients may be lost through leaching and
erosion

58. 3. Describe how atmospheric carbon dioxide
levels fluctuate daily, seasonally, and
geographically. Explain why such fluctuation
occurs.

59. Atmospheric carbon dioxide levels fluctuate on a
daily basis due to:
 consistency
 photosynthetic stages during the day
 less carbon dioxide gathered during sunlight
gathering

60. Atmospheric carbon dioxide levels fluctuate
seasonally and geographically due to:
 temperature
 solar radiation
 timing of the growing and dormant seasons
 land area

61. 4. Describe a pathway of nitrogen from the
atmosphere into the body tissue of an
herbivore.

62. Nitrogen cycle: Fixation
Biological
Fixation
Mineralization
Assimilation
Consumption by
herbivores

63. 5. Describe how an atom of phosphorus
might move from the crystal lattice of a
mineral in a rock, through a plant, and into
the ocean.

64.  phosphate salts are release from rocks
through weathering, leaching, erosion,
mining or agricultural fertilizers usually
dissolved in water
 dissolved phosphate being absorbed by
plants
 animals absorb phosphates by eating plants
or plant-eating animals
 when animals or plants die, phosphates
returns to the soil or ocean
(source: http://www.lenntech.com)

65. 6. List and describe three different inputs of
sulfur into the atmosphere.

66. Sulfur enters the atmosphere from several sources:
1. combustion of fossil fuels
2. volcanic eruptions
3. exchange at the surface of the oceans

67. 7. Describe how ozone is formed at different
levels of the atmosphere and how biological
organisms are affected by ozone.

68. Source: http://www.ozonelayer.noaa.gov