ECOSYSTEM ECOLOGY

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ECOSYSTEM ECOLOGY ENERGY FLOW CHEMICAL CYCLES
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Ecosystem a spatially explicit unit of the
Earth that includes all of the organisms, along
with all the components of the abiotic
environment within its boundaries. Gene Likens
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Ecosystem (trophic-dynamic) the system composed
of physical-chemical-biological processes active
within a space-time unit of any magnitude
Ray Lindeman 1941
Cedar Ck. Bog, MN
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Function, not Species -- Stuff, not Things
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TROPHIC STRUCTURE Defined by energy
flow. primary producer primary consumer
(herbivore) secondary consumer (carnivore) ,
top carnivore.  
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Ray Lindeman 1942 First Ecosystem model
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Eugene Odum 1953. Silver Springs, Florida.
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Fig. 6.2 Ricklefs -- E.P Odums universal model
of ecological energy flow
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ECOSYSTEM Compartments include leaves, wood,
soil, rhizosphere. Small size scale. Compartment
s contain living non-living
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Lake Wingra ECOSYSTEM BOUNDARIES
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BOUNDARIES
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ECOSYSTEM SCALES
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ECOSYSTEM ECOLOGY ENERGY
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PHOTOSYNTHESIS RESPIRATION
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Gross Primary Productivity Respiration Net
Primary Productivity NPP GPP - R
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Measuring Primary Productivity  Oxygen method c14
method a radioactive tracer technique  annual
production
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CALORIMETRY Measuring Energy Flow calorie 1
degree C increase at 15 degrees C, for 1 ml
water 1000 calories 1 Calorie carbohydrate
and protein about 5 Cal per gram fat about 9 Cal
per gram teaspoon sugar 4 grams or 20
Calories (kilocalories)
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Average Annual Net Primary Productivity, by
Habitat Ricklefs Fig. 6.8
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MASS BALANCE Application of conservation of
matter Input Output Pool (Reservoir) Equilib
rium Steady State Source Sink Flux Net Turnover
Rate Time Burial
Ricklefs Fig. 7.5 Global Carbon Cycle
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TROPHIC CONCEPTS Productivity Biomass Turnover
Time Pool/Input Biomass/Productivity Turnover
Rate Inverse of Turnover Time At equilibrium,
Input Output
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Steady State (Equilibrium) Trillions of moles
(per year) Turnover Time 38,000,000/8400 4524
years Turnover rate is about 0.022 per year
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ECOLOGICAL EFFICIENCY Ratio of the productivity
for two adjacent trophic levels. EXAMPLE primary
productivity 2 grams per m2 per day herbivore
productivity 0.2 grams per m2 per day, then
the ecological efficiency is ???
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Rule of Thumb The ecological efficiency is
10 per trophic level.
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TROPHIC CASCADES (CARPENTER) DIRECT INDIRECT
EFFECTS OF TOP PREDATORS ON BIOMASS PRODUCTIVITY
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Bottom-Up Top-Down effects
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Characteristics of Top Carnivores not dense (few
per unit area) because of ecological
efficiency large territory (widely ranging) large
body long life fast moving charismatic hunt-able,
either as trophies or varmints, not usually for
meat. Extirpation Indirect Effects Trophic
Cascade
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Microbial Loop Extra links reduce amount of
energy reaching predators by about 90.
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Atmospheric Carbon Global Warming
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ECOSYSTEM MANIPULATIONS THE NITROGEN
CYCLE Bormann and Likens (1970) -- HUBBARD BROOK,
NH ecological consequences of clear-cutting a
38-acre watershed in a New Hampshire Experimental
Forest Organic N oxidized to nitrate, producing
nitric acid pH of stream decreased nitrogen
fixation decreased nutrients rapidly flushed out
of the watershed
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Nitrogen Excretion Ammonium, Urea, Uric Acid
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P04 surrogate for primary productivity
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ECOLOGICAL STOICHIOMETRY Elemental
Ratios REDFIELD RATIO CNP
106161 CN decaying wood, DOC. NP --
cyanobacteria advantage. CP phosphate
limitation for Daphnia.