Principles of Ecology

1
Principles of Ecology

• EEP 255
• Class 12
• October 2, 2003

2
What is Ecology?

• Ecology can be defined as the study of
  relationships between organisms and the
  environment
• Ecologists study these relationships over a large
  range of temporal and spatial scales and using a
  variety of approaches.
• Scales
• Individual organisms,
• Populations
• Communities
• Ecosystems (biotic abiotic)
• Biomes
• Global

3
Environmental Factors

• Soil quality
• Water quality
• Air quality
• Temperature
• Energy
• Nutrients
• Chemicals
• Variations, sensitivity, resilience, robustness,
  dynamics

4
Dimensions

• Population distribution and abundance
• Population dynamics
• Food webs
• Competition and mutualism between organisms
• Ecosystem functions
• Energy cycles
• Bio-geochemical cycles

5
Ecosystem Functions

• Ecosystem functions transform the quality or
  spatial location of matter and energy (similar to
  economic production functions).
• Photosynthesis solar energy capture and biomass
  production
• Food Chain or Web chemical cycling and energy
  flow
• Climate System solar energy capture and transfer
• Hydrological Cycle water purification, storage,
  and transfer
• Biogeochemical Cycles (C, N, H,O and P) elemental
  matter cycling
• Evolution chemical and biological

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Biogeochemical Cycles
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Food Webs

• Aquatic
• Diatoms Phytoplankton
• Krill
• Whales,penguin
• Sharks, Seals
• Sea cucumbers

• Autotrophs (producers)
• Primary consumers
• Sec. Consumers
• Tertiary Consumers
• Decomposers

• Land Based
• Plants
• Herbivores
• Carnivores
• Carnivores
• Detrivores
• Fungi
• Centipedes

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Energy Accounts Deciduous Forest

• Solar radiation Input 100
• Reflected 15
• Heat radiated back 41
• Evaporation 42
• Absorbed by plants 2.2
• Plant respiration 1.2
• Net primary production 1
• Herbivore consumption 0.01 0.7 respi-
• Detrivore consumption 0.7 -ration
  losses
• Storage and growth
• Export to rivers

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Biomass supported (000 Kg)
Tertiary consumers
Secondary Consumers
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Hydrological Cycle
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Hydrological cycle

• Stocks
• Oceans 1.35 billion km3
• Atmosphere 13,000 km3
• Groundwater 8.2 million km3
• Polar ice 7.5 million Km3
• Surface water 3 million Km3
• Flows /yr
• Ocean evaporation 425,000 Km3
• Land evaporation 71,000 Km3
• Ocean rainfall 385,000 Km3
• Land rainfall 111,000 Km3
• River flows into ocean 40,000 Km3

12
Hydrological Cycle

• A giant water purification system using solar
  energy!
• Turnaround or renewal times
• Atmospheric water 9 days
• Rivers 12-20 days
• Lakes days to centuries
• Oceans 3100 years.

13
Carbon Cycle
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Carbon Cycle

• Stocks
• Atmosphere
• Dissolved in water (HCO3 ions)
• Fossilized organic matter (limestone, coal,
  petroleum, natural gas)
• Soil organic matter
• Flows into biosphere
• Photosynthesis (plants and algae)
• Flow back into atmosphere
• Respiration
• Decay (CO2 or Methane)
• Burning (CO2)

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Carbon Cycle Accounting
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Carbon Balance over past 150 years

• Atmospheric increase  Emissions from Fossil
  fuels  Net emissions from changes in land
  use - Oceanic uptake - Missing carbon sink
• 3.3(0.2)5.5(0.5)1.6(0.7)-2.0(0.8)-1.8(1.2)
   
• In petagrams (billion MT)

17
Nitrogen Cycle
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NITROGEN CYCLE
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Nitrogen Cycle

• Main reservoir atmosphere(79 N)
• Plants and animals need fixed nitrogen (NO3 ions,
  Ammonia, Urea)
• Lightening
• Bacterial fixing(legumes, alders, soil,
  cynobacteria in water)
• Industrial fixing
• Trophic levels (plant/animal proteins)
• Decay to ammonia
• Nitrifying bacteria (NH3 to nitrates)
• Denitrifying bacteria (nitrates to N2 gas)
• ARE Denitrifiers keeping up??

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Other chemicals

• Oxygen (along with carbon)
• Phosphorus (necessary for DNA,RNA)
• Sulfur
• Other micronutrients (Zn, Mg, etc)

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Gaia hypothesis

• The Gaia hypothesis states that the temperature
  and composition of the Earth's surface are
  actively controlled by life on the planet.
• The Gaia theory suggests that the abiotic and
  biotic environment is made up of many complex
  interrelationships
• Many of these complex interrelationships are
  quite delicate and may be altered by human
  activity to a breaking point and
• The theory suggests that humans must learn to
  respect Gaia by reducing their intentional
  modification of the Earth's abiotic and biotic
  components.