Mon. Tues. Wed. Thurs. Fri.

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Mon. Tues. Wed. Thurs.
Fri.
Week of Oct. 13
Get back to us on Lemna experiments if necessary
Week of Oct. 20
Class in Library Multimedia Room
T lab switch?
Wet, muddy outdoor lab wear closed-toed shoes
Week of Oct. 27
Independent project set-up
Week of Nov. 3
Exam 2
Forest ecology lab dress for weather
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Mistake on exam Key 15 should be b.
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Outline for ecosystems
Introduction How does energy move through an
ecosystem? How does matter move through an
ecosystem?
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All organisms participate in element cycling.
Each group will be assigned one of the following
element cycles (C, N, P, S). Describe 5 ways
that your everyday activities contribute to the
element cycles (hint think about the indirect
effects of your activities). In your answer,
include 1 process that transforms an element from
inorganic to organic form, 1 process that
transforms an element from organic form to
inorganic form, and 1 non-biological
transformation.
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Carbon cycle Driving a car, smoking a cigarette,
burning oil Respiration Growing plants for
food Compost pile in back yard Carbon from
fossil fuel burning dissolves into ocean and
precipitates as limestonec
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Nitrogen cycle Driving a car Growing plants for
food N fertilizer Eating plants and excreting
excess N Planting soybeans and clover Using
excess N fertilizer that runs off into streams
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Sulfur cycle Driving a car Burning coal
produces acid rain Eating plants and excreting
excess S Planting vegetation Walking on dirt
paths rather than sidewalk
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Phosphorus cycle Growing plants for food P
fertilizer Sedimentation and burial of P in
lakes Eating plants and excreting excess P P in
sewage discharged to water stimulates algal
growth Tilling land for agriculture releases P
into air
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How does matter move through an
ecosystem? Nutrient recycling in terrestrial
and aquatic ecosystems
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Nutrient recycling in terrestrial systems -
where is it happening?
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Nutrient recycling in terrestrial systems - new
weathering of bedrock provides small amount of
nutrients taken up by vegetation each year
(10) - how do we know that?
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• -mass balance
• inputs outputs
• weathering precipitation loss in streams

calculate by difference
measure
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Figure 8.2
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Figure 8.3
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• Organic matter decomposition
• Leaching of soluble compounds by water
• Consumption by detritus-feeding orgs.
• e.g., earthworms, millipedes, etc.
• Breakdown of rest by fungi and bacteria
• - how do they decompose?
• What factors affect rate of decomposition?

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Effect of rainfall on rate of leaf decomposition
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Which column is larger?
Tropical Temperate
Litter/living leaf Soil P/plant P Soil N/plant
N of total org C
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Land use affects phosphorus retention in a system
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Nitrogen fixation can increase nitrogen avail.
Litter quality (nitrogen content) of different
tree species
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Mychorrhizae increase nutrient content of plants
Fig. 8.7
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Nutrient recycling in aquatic systems - where
is it happening?
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• sediments not in contact with pelagic zone
• most sediments are anaerobic
• - reactions are slower

Pelagic zone
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Figure 8.12
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Water below the thermocline may become depleted
of oxygen in summertime Why?
Warm (low density) water
Cool (dense) water
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Fig. 8.16
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Low oxygen in facilitates recycling of some
nutrients (P and Fe) When oxygen is present, P
and Fe combine to form insoluble compounds which
remain in the sediments When oxygen is absent,
P and Fe are soluble and remain in water can
be mixed up into pelagic zone and taken up by
algae
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Fig. 8.17
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Which nutrient is most limiting to
aquatic systems?? What do I mean by most
limiting?
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P - limitation
Housatonic
Goal to decrease N input to LIS by 55 in 15 years
Where does P-limitation switch to
N-limitation? How will changes in nutrient
loading affect species composition and
frequency of algal blooms?
LIS
N-limitation
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Example of using properties of nutrient recycling
in aquatic systems to reduce algal blooms in
freshwater systems
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How could this reduce algal blooms?
Fountain ?
Thermocline ?
oxygen
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Nutrient recycling - Terrestrial systems -
soil - weathering of rock - decomposition
of organic matter - Aquatic systems -
sediments and deep water - reactions slow
(anaerobic) - decomposition not near uptake