Transcript Chapter 4

News
Guns in National Parks
 GSMNP
 Python bounty hunters
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Ecosystems
Ecology -- Interactions between living and
nonliving elements that sustain life
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Biotic community
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Ecosystem
Affected by external/internal factors
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Perturbations
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Fire, hurricanes, insects, over grazing, timbering
Anthropogenic or “natural”
All recovering from some past disturbance
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Living parts of an ecosystem
Nothing is constant except change
Everything is connected to everything else
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Limits difficult to define
Ecosystems
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Perturbations (disturbance)
 Anthropogenic
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DDT killed bugs, but also thinned egg shells of
eagles, falcons, etc.
 Chernobyl
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10% fallout over Sweden
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Lichens “radiation sponges”
 Symbiotic fungus and algae
Wildlife haven??
Spills, atmospheric deposition
Natural? disturbance
Ecosystems
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Scale
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Large
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Smaller
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Longleaf pine forest
Regenerating stand
Smaller still
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Biosphere
Biome
Single tree
Boundaries difficult to define
Ecosystems
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Self sustaining?
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Entropy
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Second Law of Thermodynamics
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Entropy is a measure of disorder (and order)
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Entropy tends to increase over time
the higher the entropy the greater the disorder
Nature should inexorably degenerate toward a state of
greater disorder, greater entropy
So how are living systems ordered?
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Energy is required
 Ordering must be balanced with disorder (closed system)
 Ecosystems must be open systems -- connected
Ecosystems
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Cities don’t qualify as ecosystems?
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Not self-sustaining?
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But ecosystems couldn’t be sustained either
w/o a lot of energy input
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Because they import a lot of energy
Raw materials transformed but little replenished
Wildfire transforms, does it replenish?
Do cities meet the definition of ecosystem?
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If it takes a lot of human interference, then it’s not
an ecosystem?
Manipulate Ecosystems
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Wildlife management intentionally
manipulates communities and
ecosystems (to achieve a goal)
 That’s
why the chapter seems to focus on
disturbance
Matter and Energy
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Carbon based
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Photosynthesis
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Organic chemistry
CO2 + H20 = sugars + O2
Galapagos Rift
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Volcanic hydrothermal vents
Sulfur-based life
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Chemoautotrophic bacteria
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Hyperthermophiles
SLMEs
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Subsurface lithoautotrophic microbial ecosystems
Food (Chains) Webs
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All require energy and matter
Trophic levels
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Primary producers - autotrophs
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Plants
Consumers
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Primary consumers
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Secondary
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Carnivore
Tertiary
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Herbivores
Top level carnivores
Decomposers
Food (Chains) Webs
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Trophic pyramid
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Represent flow of energy
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10% efficient
Biomass too
Inverted pyramid
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Aquatic phytoplankton and zooplankton
Small biomass of autotrophs supports a large
mass of longer lived herbivores
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Rapid turnover of autotrophs
Detritus based -- energy of mountain streams from outside
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Can’t have a lot of top level carnivores
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Energy Transfer
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Less energy (per unit area) at each
level of the trophic pyramid
 Plants
> Herbivores > Carnivores
 Prey populations limit the number of
predators, not vise versa
 Eat low on the food chain
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Length of the food chain is limited
Energy Transfer
Isle Royale
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1 kg wolf : 59 kg moose : 765 kg browse
Wolf = 50 kg Moose = 300 kg
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Wolf needs to eat about 10 moose per wolf per year
Striper fisherman at Lake Norman
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Want lots of large stripers
So they want to stock more stripers
Does this make any sense?
Range of Tolerance (Ecological
Amplitude)
Temperature, moisture, heat, salinity,…
 Halophytes
 Steno -- narrow
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 Stenophagus -- Everglades
 Stenoky -- RCW
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Eury -- wide
 Eurythermal
 Euroky
 Euryphagus --
wild pigs
kite
Thermoneutral Zone
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Zone of ambient temperature defined by
upper and lower critical limits. Within
this zone metabolism is at the basal
rate.
 Outside
this range metabolism increases to
maintain body temperature.
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Beaver example
Circadian rhythms
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A circadian rhythm is an approximate daily
periodicity, a roughly 24-hour cycle in the
biochemical, physiological or behavioral
processes of living beings, including plants,
animals, fungi and cyanobacteria.
 Circadian rhythms are endogenously
generated, and can be entrained by external
cues, called Zeitgebers. The primary one is
daylight.
Circadian rhythms
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The rhythm is linked to the light-dark cycle.
Animals, including humans, kept in total
darkness for extended periods eventually
function with a freerunning rhythm. Each
"day," their sleep cycle is pushed back or
forward, depending on whether their
endogenous period is shorter or longer than
24 hours. The environmental cues that each
day reset the rhythms are called Zeitgebers
(from the German, Time Givers)
Niche
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Animal’s “profession” Habitat “address”
Multidimensional hyperspace
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Generalists vs. specialists
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Spruce grouse -- winter diet jack pine needles
Ruffed grouse -- aspen catkins
Ecological equivalent
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Euroky vs. stenoky
Sympatric species
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Climatograph 2 dimensions (temp, rain)
Capercaillie -- Scot’s pine in Europe
Robin vs. Woodcock
Niche
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Damaged ecosystems
 Do
they have the original niches?
Two species cannot occupy the same
niche at same place and time
 Empty niche?
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 Exotic
species
 Feral
 Out
cats
compete native species
 Examples?
Changes in Space and Time
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Spatial
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Biomes -- climate determined
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Temporal
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Succession
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Primary vs. secondary
Successional sere
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Dominant plants
Grassland, deciduous forest
Pioneer to climax
Let’s do NC Piedmont together!!!
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Johnston and Odum pdf
Changes in Space and Time
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Climax
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Examples
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Self-perpetuating community?
Dynamic equilibrium?
Spruce-fir, oak-hickory, tall grass prairie
Longleaf pine (disequilibrium)
Long-lasting communities
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Loss of chestnut
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Frasier fir and eastern hemlock to follow?
Changes in Space and Time
Aquatic ecosystems
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Oligotrophic
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Geologically young, “few nutrients”
Eutrophic
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A lot of nutrients
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Succession is oligotrophic to eutrophic
 Eutrophication
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Sewage
 Lake Erie
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1960-70’s “dead”
Phosphorus from detergents
Algae blooms, high BOD (biological oxygen demand), anoxia
In 1970’s- 80’s controlled nutrient inputs and anoxia levels decreases
In 90’s anoxic zones, dead zones, began to increase again, why?
Stratified longer due to global warming, so more BOD below thermocline?
Succession & Wildlife Mgt
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Early successional species
 “r”
selected
 Disturbance dependent environments
 High reproductive potential
 Short lived, rapid turnover
 Good dispersers
 Smaller size
Successional “threat”
 Many, but not all, disturbancedependent species doing well
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Succession & Wildlife Mgt
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Late successional species
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“K” selected
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Stable communities
Good competitors
Long lived, slow turnover
Low reproductive potential
Poor disperses
Larger size
Climax species -- tendency to not do well
Diversity r/K Strategies
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Intermediate Disturbance Hypothesis
 Too
little, K-strategists dominate
 Too much, r-strategists dominate
 Intermediate disturbance frequency yields
maximum species diversity
Succession & Wildlife Mgt
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Disturbance communities are more
abundant than climax communities
Diversity and Stability
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Species diversity
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Abundance
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S = Number of species = species richness
N = population size
Density = N/unit area = N/A
Latitudinal gradient in species diversity
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Tropics - high S, low number of individuals per
species
Poles - vise versa
Diversity/Stability
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How to measure diversity?
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S = species richness
Shannon-Weaver Index (H’)
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All kinds of diversity
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Includes numbers of individuals per species
Evenness (equitability), equal number of individuals per
species
Higher S, higher H’
more evenness, higher H’
H’max = lnS
Genetic, individual, species, community, etc
Trying to resolve diversity into a single
number is problematic
Spe cie s
n
p
A
B
C
D
30
20
40
10
0.3
0.2
0.4
0.1
-1.204
-1.609
-0.916
-2.303
ln p
-0.361
-0.322
-0.367
-0.230
pl np
10 0
1
H'=
-1.280
Spe cie s
n
p
ln p
pl np
A
25
0.25
-1.386
-0.347
B
C
D
25
25
25
0.25
0.25
0.25
-1.386
-1.386
-1.386
-0.347
-0.347
-0.347
10 0
1
H'=
-1.386
H'=
S=
ln S = Hma x=
J=H'/Hma x
1.280
4
1.386
0.923
H'=
1.386
sp eci es
a
b
c
d
e
N
15
20
10
40
15
10 0
p
0.15
0.2
0.1
0.4
0.15
ln p
-1.8971 2
-1.6094 379
-2.3025 851
-0.9162 907
-1.8971 2
pl np
-0.2845 68
-0.3218 876
-0.2302 585
-0.3665 163
-0.2845 68
-1.4877 984
a
b
c
d
e
15 0
20 0
10 0
40 0
15 0
10 00
0.15
0.2
0.1
0.4
0.15
-1.8971 2
-1.6094 379
-2.3025 851
-0.9162 907
-1.8971 2
-0.2845 68
-0.3218 876
-0.2302 585
-0.3665 163
-0.2845 68
-1.4877 984
a
b
c
d
e
f
g
h
I
j
20
7
5
5
8
30
5
10
8
2
10 0
0.2
0.07
0.05
0.05
0.08
0.3
0.05
0.1
0.08
0.02
-1.6094 379
-2.6592 6
-2.9957 323
-2.9957 323
-2.5257 286
-1.2039 728
-2.9957 323
-2.3025 851
-2.5257 286
-3.9120 23
-0.3218 876
-0.1861 482
-0.1497 866
-0.1497 866
-0.2020 583
-0.3611 918
-0.1497 866
-0.2302 585
-0.2020 583
-0.0782 405
-2.0312 03
a
b
c
d
e
f
g
h
I
j
10
10
10
10
10
10
10
10
10
10
10 0
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
-2.3025 851
-2.3025 851
-2.3025 851
-2.3025 851
-2.3025 851
-2.3025 851
-2.3025 851
-2.3025 851
-2.3025 851
-2.3025 851
-0.2302 585
-0.2302 585
-0.2302 585
-0.2302 585
-0.2302 585
-0.2302 585
-0.2302 585
-0.2302 585
-0.2302 585
-0.2302 585
-2.3025 851
H'
5 species, unevenness
-1.4877 984
-1.4877 984
-2.0312 03
Same as above, but 10x more numbers
H’ is the same
10 species, unevenness; same
number of individuals as the
top example; H’ greater
Same as above but even; H’ greater
-2.3025 851
Diversity/Stability
Text definition of stability
Relative consistency in the abundance of populations
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There is no such thing.
Text definition is overly simplistic
Diversity/Stability
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Equilibrium stability
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Resilience
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Returns to original state after perturbation
No perturbation, no change
Short time to return to original state after perturbation
Rapid recoil
Tundra vs. pine woods
Resistance
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How much perturbation is needed to effect change?
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A little, unstable
 A lot, stable
Diversity/Stability
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Early ecologists
 Greater
diversity = stability
 Intuitive appeal, but data to support?
Diversity/Stability
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Now
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W/in ecosystem diversity and stability tend to be
positively correlated
Diversity is not a driver, but a consequence
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It’s not a mechanism (interactions, processes)
What is the mechanism?
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Interactions among species?
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Weak, then more independent, and more stable
Strong, then more dependent, and less stable
Differential response of species or guilds (functional
groups) to varying conditions
Diversity/Stability
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Symbiosis
 General
term for the relationship between
dissimilar organisms

Specific types
 Mutualism
-- both benefit
 Lichens -- fungus and algae
 Obligatory vs. facultative
 Commensalism
-- one benefits, other not
harmed -- mussels?
 Parasitism -- one benefits, other harmed
Diversity/Stability
Example of mutualism???
 Calvaria forests on Mauritius and the
dodo
 Calvaria
major (Dodo tree) (old scientific
name)
 Tambalacoque
(Sideroxylon grandiflorum)
Diversity/Stability

Pollution tends to simplify communities
 EPT
index
 The abundance of macroinvertebrates in
streams
 orders
Ephemeroptera (mayflies), Plecoptera
(stoneflies), and Trichoptera (caddisflies)
 Sum of the number of Ephemeroptera,
Plecoptera, and Trichoptera divided by the total
number of midges (Diptera: Chironomidae)
Diversity/Stability
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Monocultures
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Maintaining biodiversity is a good thing
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Agriculture
Forestry
“To keep every cog and wheel is the first
precaution of intelligent tinkering” Leopold
Society for Conservation Biology (SCB)

To advance the science and practice of conserving
the Earth's biological diversity.
Diversity/Stability Debate

Why important?
 Great
 Great
loss in species diversity
increase in invasive exotics
Implicit assumption that ecosystems
evolved the ability to withstand these
assaults
 Will this destabilize ecosystems?
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