1. Ecosystems & Restoration Ecology
Campbell & Reece
Chapter 55

2. Ecosystems no matter what size; 2 processes occurring: energy flow
chemical cycling

3. Conservation of Energy
1st Law of Thermodynamics:
nrg can neither be created or destroyed, only transferred or transformed
2nd Law of Thermodynamics:
every exchange of nrg increase the entropy of the universe
lost nrg: heat

4. Conservation of Mass matter can neither be created or destroyed
elements not significantly gained or lost on a global scale but can be gained or lost from a particular ecosystem
in nature most gains & losses to ecosystems small compared to amt cycled but balance between inputs & outputs determines if given ecosystem is a source or a sink for a given element

6. Energy, Mass, & Trophic Levels
trophic levels are based on their main source of nutrition & nrg
Primary Producers ultimately support all other levels
biosphere‘s main autotrophs:
plants
algae
photosynthetic prokaryotes

8. Definitions Detritus: nonliving organic material
Detritivores: decompsers

10. Global Energy Budget
every day Earth’s atmosphere bombarded by ~ 10²² joules of solar radiation
(or enough nrg to supply demands of Earth’s human population for ~25 yrs using 2009 levels)
most incoming solar radiation is absorbed, scattered or reflected by clouds & dust in the atmosphere
amt that actually reaches Earth’s surface limits the possible photosynthetic output of ecosystems

11. Gross & Net Production
GPP: gross primary production = amt nrg from light (or chemicals in chemoautotrophic systems) converted to the chemical nrg of organic molecules per unit time
NPP: net primary production = GPP – nrg used by primary producers for their own respiration (Ra)
NPP = GPP – Ra
NPP =/= total biomass of photosynthetic autotrophs present; NPP = amt new biomass added in given period of time

12. Primary Production
amt of light nrg  chemical nrg by autotrophs in an ecosystem during given time
GPP: total nrg assimilated by an ecosystem in given time
NPP: nrg accumulated in autotroph biomass,

13. Net Ecosystem Production
total biomass accumulation of an ecosystem =
GPP – total ecosystem respiration
satellites used to study global patterns of primary production
show ecosystems vary considerably
tropical rainforest highest
coral reefs & estuaries high but global total is low because only cover ~1/10th what rainforest do

14. Primary Production in Aquatic Ecosystems
limited by light & available nutrients

15. Primary Production in Terrestrial Ecosystems
globally limited by:
temperature
moisture
locally limited by:
a particular soil nutrient

16. Limiting Nutrient
is the element that must be added for production to increase
in marine ecosystems it is most often N or P

18. Secondary Production
amt of chemical nrg in consumers’ food that is converted to their own new biomass during a given period of time
vast majority of an ecosystem’s production is eventually consumed by detritivores

19. Energy partitioning w/in a Link of the Food-Chain

20. Production Efficiency
efficiency with which food nrg is converted to each link in a food chain
another way:
Production Efficiency is the % of nrg stored in assimilated food not used for respiration

21. 10% Efficiency in Energy Transfers
Production efficiency =
Net secondary production x 100
Assimilation of primary production

22. Trophic Efficiency
% of production transferred from 1 trophic level to the next
~ 5% – 20% with 10% being typical
Pyramids of nrg & biomass reflect low trophic efficiency
aquatic ecosystems can have inverted biomass pyramids: producers grow, reproduce & are consumed so quickly there is no time to develop a large population

27. Biogeochemical Cycles
photosynthetic organisms essentially have unlimited supply of solar nrg but have limiting amts of chem elements
atoms taken in by organism either  assimilated or wastes
organism dies: atoms replenish pool of inorganic nutrients  used by other organisms
this cycling of nutrients involving biotic & abiotic components called: biogeochemical cycles

30. Water Cycle: Biological Importance
essential to all organisms
availability influences rates of ecosystem processes
especially 1° production & decomposition in terrestrial biomes

31. Water Cycle: Forms Available to Life
most water used in its liquid phase
seasonal freezing limits soil water’s availability to terrestrial organisms

32. Water Cycle: Reservoirs

33. Water Cycle: Key Processes
main processes driving water cycle:
evaporation of liquid water by solar radiation
condensation of water vapor
Precipitation
Transpiration
Runoff : surface or percolation  groundwater

35. Carbon Cycle: Biological Importance
C forms framework of organic molecules essential to all living organisms

36. Carbon Cycle: Forma Available to Life
photosynthetic organisms utilize CO2 converting inorganic C  organic C

37. Carbon Cycle: Reservoirs
fossil fuels
sediments of aquatic ecosystems
soils
plant & animal biomass
atmosphere (CO2)

38. Carbon Cycle: Key Processes
removing CO2 from atmosphere:
photosynthesis
returning CO2 to atmosphere:
cellular respiration
burning of fossil fuels & wood
volcanic eruptions

40. Nitrogen Cycle: Biological Importance
N part of a.a., proteins, & nucleic acids

41. Nitrogen: Forms Available to Life
plants can assimilate 2 forms of N:
ammonium:
nitrate

42. Nitrogen: Forms Available to Life
bacteria can use both these & nitrite, NO2-

43. Nitrogen: Forms Available to Life
animals can only use organic forms of N

44. Nitrogen Cycle: Reservoirs
main reservoir of N is the atmosphere (80% free N gas)
others:
soil
sediments of rivers, lakes, oceans
biomass

45. Nitrogen Cycle: Key Processes
Nitrogen Fixation:
N2  forms that can be used to synthesize organic N cpds
natural methods:
certain bacteria or lightening
man activities:
industrial production of fertilizers
legume crops

46. Nitrogen Cycle: Key Processes
Denitrification:
certain bacteria in soil
organic N  N2 gas (reduction of N2 )

48. The Phosphorus Cycle

49. Phosphorus Cycle: Biological Importance
P is major component of
Nucleic Acids
Phospholipids
ATP

50. Phosphorus Cycle: Forms Available to Life
plants absorb phosphate ion  organic molecules

51. Phosphorus Cycle: Reservoirs
sedimentary rock of marine origin is largest reservoir
also in soil, dissolved in oceans & in biomass
recycling of P tends to be localized in ecosystems

52. Phosphorus Cycle: Key Processes
weathering of rocks gradually adds P to soil
some taken up by plants  food webs  decomposition of biomass returns P to soil
some  runoff  oceans
almost no P in atmosphere

54. Decomposition Rates
determine the proportion of a nutrient in a particular form
is determined by same factors that limit primary production:
temperature
moisture
nutrient availability

55. Decomposition in Rainforest
is rapid  relatively little organic material accumulates on floor
~ 75% of nutrients in ecosystem is in woody trunks of trees ….only ~10% is in the soil

56. Decomposition Rates
temperate forests because decomp much slower  up to 50% of all organic material in soil
decomp slower when land is either too dry for decomposers to survive or too wet to supply them with enough O2
ecosystems wet & cold (peatlands) store large organic matter (decomposers grow poorly):
primary production >>decomp

58. Decomposition Rates in Aquatic Ecosystems
anaerobic muds: can take > 50 years
algae & aquatic plants usually assimilate nutrients directly from the water so lake sediments act as nutrient “sink”

60. Restoration Ecology
bioremediation : use of organisms to detoxify & restore polluted & degraded ecosystems
biological augmentation: an approach to restoration ecology that uses organisms to add essential materials to a degraded ecosystem

61. Bioremediation

62. Biological Augmentation