Ecology 5

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Ecology 5 Ecosystem Structure and
Dynamics Introduction to Conservation
Biology Readings Ch. 36.8 to 36.20
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• Predation by killer whales on sea otters,
  allowing sea urchins to overgraze on kelp
• Sea otters represent the keystone species

Figure 36.4B
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Energy flow and chemical cycling are the two
fundamental processes in ecosystems
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• A terrarium ecosystem

Chemical cycling(C, N, etc.)
Chemicalenergy
Heatenergy
Lightenergy
Figure 36.8
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Trophic structure is a key factor in ecosystem
dynamics
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TROPHIC LEVEL
Quaternaryconsumers
Carnivore
Carnivore
Tertiaryconsumers
Carnivore
Carnivore
Secondaryconsumers
Carnivore
Carnivore
Primaryconsumers
Herbivore
Zooplankton
Producers
Plant
Phytoplankton
Figure 36.9A
A TERRESTRIAL FOOD CHAIN
AN AQUATIC FOOD CHAIN
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• Decomposition is the breakdown of organic
  compounds into inorganic compounds

Figure 36.9B
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Food chains interconnect, forming food webs
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Wastes anddead organisms
Tertiaryandsecondaryconsumers
Secondaryandprimaryconsumers
Primaryconsumers
Producers
Detritivores
(Plants, algae,phytoplankton)
(Prokaryotes, fungi,certain animals)
Figure 36.10
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Energy supply limits the length of food chains
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• A pyramid of production reveals the flow of
  energy from producers to primary consumers and to
  higher trophic levels

Tertiaryconsumers
10 kcal
Secondaryconsumers
100 kcal
Primaryconsumers
1,000kcal
Producers
10,000 kcal
1,000,000 kcal of sunlight
Figure 36.11
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• Only about 10 of the energy in food is stored at
  each trophic level and available to the next level

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Is meat is a luxury for humans ?
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Chemicals are recycled between organic matter and
abiotic reservoirs
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• There are four main abiotic reservoirs

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Water moves through the biosphere in a global
cycle
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Solar heat
Net movementof water vaporby wind (36)
Water vaporover the land
Water vaporover the sea
Evaporationandtranspiration(59)
Precipitationover the land(95)
Precipitationover the sea(283)
Evaporationfrom the sea(319)
Oceans
Surface waterand groundwater
Flow of waterfrom land to sea(36)
Figure 36.14
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The carbon cycle depends on photosynthesis and
respiration
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CO2 in atmosphere
Burning
Cellular respiration
Plants,algae,cyanobacteria
Photosynthesis
Higher-levelconsumers
Primaryconsumers
Wood andfossil fuels
Decomposition
Detritivores(soil microbesand others)
Detritus
Figure 36.15
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The nitrogen cycle relies heavily on bacteria
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Nitrogen (N2) in atmosphere
Amino acidsand proteins inplants and animals
Assimilationby plants
Nitrogenfixation
Denitrifyingbacteria
Detritus
Nitrogen-fixingbacteria in rootnodules of
legumes
Nitrates(NO3)
Detritivores
Nitrogen-fixingbacteria in soil
Decomposition
Nitrifyingbacteria
Nitrogenfixation
Ammonium (NH4)
Figure 36.16
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The phosphorus cycle depends on the weathering of
rock
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Upliftingof rock
Phosphatesin organiccompounds
Weatheringof rock
Phosphatesin rock
Animals
Plants
Runoff
Detritus
Phosphatesin solution
Phosphatesin soil(inorganic)
Decomposition
Detritivoresin soil
Rock
Precipitated(solid) phosphates
Figure 36.17
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Ecosystem alteration can upset chemical cycling
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Figure 36.18A
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• In 1966, one of the valleys was completely logged

Figure 36.18B
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Figure 36.18C
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• Environmental changes caused by humans can
  unbalance nutrient cycling over the long term

Example acid rain
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David Schindler talks about the effects of
nutrients on freshwater ecosystems
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Figure 36.19B
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• According to Dr. Schindler, there are three
  serious threats to freshwater ecosystems

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Zoned reserves are an attempt to reverse
ecosystem disruption
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Why do we want to conserve Nature?

• Four Reasons
• Utilitarian
• Functional
• Esthetic
• Ethical

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• Costa Rica has established eight zone reserves

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• On this map, the reserves are shown in green and
  the buffer zones in yellow

NICARAGUA
Caribbean Sea
Llanuras deTortuguero
COSTARICA
Guanacaste
LaAmistad
Arenal
BajoTempisque
CordilleraVolcanica Central
Pacifico Central
Peninsula de Osa
PANAMA
Pacific Ocean
Figure 36.20