Ecosystem Ecology

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Ecosystem Ecology   III. Productivity, Diversity,
and Stability
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A. Productivity 1. Gross Primary
Productivity Total photosynthetic
productivity CO2 H20 -----gt Glucose O2
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A. Productivity 2. Net Primary Productivity
NPP GPP - respiration (Plants use some of the
energy they absorb it is not stored as biomass.
NPP is only the amount stored as new biomass.)
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B. Diversity - Relationships with Productivity
1. Productivity increases diversity
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B. Diversity - Relationships with Productivity
1. Productivity increases diversity
- QUANTITATIVE EFFECT If you have more
productivity at the base of a food web, then you
can build a longer food chain (adding additional
levels AND species). And then get keystone
effects.
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B. Diversity - Relationships with Productivity
1. Productivity increases diversity
- QUALITATIVE EFFECT An increase in
productivity may also occur because more types of
food have been added. This may allow for more
specialization at the next trophic level - and
the coexistence of more species.
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B. Diversity - Relationships with Productivity
1. Productivity increases diversity 2.
Diversity increases productivity
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- Sampling Effects More diverse communities
are more likely to contain the most productive
species, and thus raise the total productivity.
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- Niche Complementarity More diverse
communities are more likely to contain different
types of species that use different types of
energy... thus more efficiently harvesting the
available energy
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Monoculture
Polyculture
They all need the same things at the same
concentrations have to place them far apart to
reduce competition.
Combinations of different plants can be planted
at higher density, and they use different
"niches" and coexist. Even if abundance of "most
productive" species, drops, this loss can be
offset.
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- Positive Interactions More diverse
communities may contain species that benefit
other species, and thus increase the productivity
of the whole community
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Monoculture
Polyculture
without beans
with beans
They all need the same things at the same
concentrations have to place them far apart to
reduce competition.
Nitrogen fixing legumes (beans) nutrify the soil,
increasing the growth of other plants
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Diversity and Productivity in a Long-Term
Grassland Experiment Tilman, et al. 2001. Science
294. 843 - 845
Cedar Creek Ecosystem Science Reserve
- 168 9 m x 9 m plots - 1, 2, 4, 8, or 16
species randomly chosen from a pool of 18
species 4 species, each, of C4 grasses, C3
grasses, legumes, non-legume forbs 2 species of
woody plants. - 35 replicates of each treatment
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Diversity and Productivity in a Long-Term
Grassland Experiment Tilman, et al. 2001. Science
294. 843 - 845 Dotted line is biomass in a
monoculture of the most productive species.
Higher productivity than this, at higher richness
values, means niche complementarity or positive
effects must be occurring.
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Diversity and Productivity in a Long-Term
Grassland Experiment Tilman, et al. 2001. Science
294. 843 - 845 Dotted line is biomass in a
monoculture of the most productive species.
Higher productivity than this, at higher richness
values, means niche complementarity or positive
effects must be occurring.
So, many random assemblages of multiple species
have biomass above that of the most abundant
monoculture (cant just be sampling effect).
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Diversity and Productivity in a Long-Term
Grassland Experiment Tilman, et al. 2001. Science
294. 843 - 845 Dotted line is biomass in a
monoculture of the most productive species.
Higher productivity than this, at higher richness
values, means niche complementarity or positive
effects must be occurring.
So, many random assemblages of multiple species
have biomass above that of the most abundant
monoculture. And we might expect greater niche
complementarity in natural systems
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Additional Experiments and Results - Foliar
fungal disease incidence decreased at higher
diversity because of greater distance between
individuals of a species, and resultant lower
rates of disease spread (Mitchell et al. 2002).
(Dilution Effect) - Greater plant diversity
led to greater abundance and diversity of
herbivorous insects, and this effect continued up
the food web to predator and parasitoid insects
(Haddad et al. 2001). (Qualitative Effects of
Diversity)
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Additional Experiments and Results - Fewer
novel plant species invaded higher diversity
treatments because of their lower soil NO3
levels, greater neighborhood crowding and
competition, and greater chance that functionally
similar species would occur in a given
neighborhood (Figs 3 Naeem et al. 2000, Kennedy
et al. 2002, Fargione et al. 2003, Fargione and
Tilman 2005a, 2005b). Greater plant species
numbers led to greater ecosystem stability (lower
year-to-year variation in total plant biomass)
but to lower species stability (greater
year-to-year variation in abundances of
individual species), with the stabilizing effect
of diversity mainly attributable to statistical
averaging effects and overyielding effects (Fig
4 Tilman et al, submitted). Data gathered this
past field season shows that soil total C has now
become an increasing function of plant species
numbers (Fig 5).
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Additional Experiments and Results - Greater
plant species numbers led to greater ecosystem
stability (lower year-to-year variation in total
plant biomass) but to lower species stability
(greater year-to-year variation in abundances of
individual species).
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Additional Experiments and Results - Stored
soil carbon increases with diversity.
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- Effects of Genetic Diversity Example
Crutsinger, et al. 2006. Science 313
966-968. Methods - 63 1m2 plots, each
containing 12 plants of all goldenrod. - The
plants in a plot represent either 1, 3, 6, or 12
genotypes, randomly selected from a pool of 21
genotypes.
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- Example Crutsinger, et al. 2006. Science 313
966-968. Results 1 ANPP correlated with number
of genotypes in plot.
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- Example Crutsinger, et al. 2006. Science 313
966-968. Results 1 ANPP correlated with number
of genotypes in plot. 2 Total insect species
diversity, and diversity of herbivores and
predators, correlate with ANPP and number of
genotypes per plot.
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- Example Crutsinger, et al. 2006. Science 313
966-968. Results 4 ANPP increase is NOT due to
a sampling effect. Evidence favors niche
complementation (p 0.07).
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- Example Crutsinger, et al. 2006. Science 313
966-968. Results 5 Increase in herbivorous
insects due to both MORE food (ANPP -
quantitative effect) and DIFFERENT food (niche
differentiation - qualitative effect).
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- Example Crutsinger, et al. 2006. Science 313
966-968. Results 6 Increase in predator
richness due to increase in herbivore richness,
not AMOUNT of food. Some herbivores were only
associated with some genotypes.
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- Example Crutsinger, et al. 2006. Science 313
966-968. Conclusions ANPP increased with
genetic diversity, probably as a function of
niche complementarity.
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- Example Crutsinger, et al. 2006. Science 313
966-968. Conclusions ANPP increased with
genetic diversity, probably as a function of
niche complementarity. Diversity in higher
trophic levels increased with increased ANPP and
greater genetic diversity. Herbivore richness is
a function of both increased abundance and niche
complementarity. Predators increase largely due
to a greater variety of herbivores.
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- Example Crutsinger, et al. 2006. Science 313
966-968. Conclusions ANPP increased with
genetic diversity, probably as a function of
niche complementarity. Diversity in higher
trophic levels increased with increased ANPP and
greater genetic diversity. Herbivore richness is
a function of both increased abundance and niche
complementarity. Predators increase largely due
to a greater variety of herbivores. So, genetic
variation WITHIN species, and not just diversity
among species, may be critical to the
conservation of productive and species-rich
communities.
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C. Effects on Stability
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C. Effects on Stability 1. Types -
"resistance to change" - "resilience after
change"
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C. Effects on Stability 1. Types 2.
Relationships with diversity - more diverse
communities are less susceptible to single "types
of disturbance" - (a pest, a flood, a drought) -
because the many species are unlikely to be
sensitive to the same thing.
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C. Effects on Stability
Biodiversity and Ecosystem Functioning Current
Knowledge and Future Challenges. Loreau, et al.
2001. Science 294 804 - 808
As richness increases, productivity become less
variable (more stable).
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C. Stability 1. Types 2. Relationships with
diversity - diverse communities may recover more
rapidly, too (resilience).... but they may
not. Fisheries ... yes Rain forest... maybe not
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Stimulate condensation and precipitation
Volatiles released
Rainforests feed themselves and water themselves.
Decomposition rapid
Absorption rapid
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CUT FOREST DOWN
Select for fire-adapted grasses.... rainforest
doesn't come back....
Nutrient runoff then reduced
rainfall INCREASE FIRE
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RAINFOREST (wet, few fires)
"Multiple Stable States"
GRASSLAND (dry, many fires)
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We are dependent on the environment for food and
resources. Ideally, we would like a STABLE,
PRODUCTIVE supply of these resources.... right??
FEAST
FAMINE
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(We don't want "boom and bust", "feast and
famine" scenarios....)
FEAST
FAMINE
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We are dependent on the environment for food and
resources. Ideally, we would like a STABLE,
PRODUCTIVE supply of these resources....
right?? (We don't want "boom and bust", "feast
and famine" scenarios....)
STABILITY
?
PRODUCTIVITY
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We are playing jenga with our life support
systems...
de Ruiter et al. 2005. Food Web Ecology Playing
Jenga and Beyond Science 30968 - 71
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Simple Predictable Realistic?
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Realistic Complex Predictable?
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But what else does biodiversity do??
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2) Biodiversity improves ecosystem services
Estimates of various Ecosystem Services - U.S. trillions Estimates of various Ecosystem Services - U.S. trillions
Ecosystem services Value(trillion US)
Soil formation 17.1
Recreation 3.0
Nutrient cycling 2.3
Water regulation and supply 2.3
Climate regulation (temperature and precipitation) 1.8
Habitat 1.4
Flood and storm protection 1.1
Food and raw materials production 0.8
Genetic resources 0.8
Atmospheric gas balance 0.7
Pollination 0.4
All other services 1.6
Total value of ecosystem services 33.3
Source Adapted from R. Costanza et al., The Value of the Worlds Ecosystem Services and Natural Capital, Nature, Vol. 387 (1997), p. 256, Table 2. TOTAL GLOBAL GNP (1997) 18 trillion. Source Adapted from R. Costanza et al., The Value of the Worlds Ecosystem Services and Natural Capital, Nature, Vol. 387 (1997), p. 256, Table 2. TOTAL GLOBAL GNP (1997) 18 trillion.
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GLOBAL GDP 2011 75 trillion
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Based on different criteria, this is the
ecosystem value we lost in that 14 year span.
GLOBAL GDP 2011 75 trillion
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3) Aesthetics and Inspiration Biodiversity
enriches our cultures
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3) Aesthetics and Inspiration Biodiversity
enriches our cultures
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4) Fights Disease
Lyme Disease - fragmentation reduces patch
size - abundance of predators like fox declined
- white-footed mice (host of Borrela burgdorferi
bacterium) increase. - increase host density,
increase infection rate of ticks.
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West Nile Virus
Low Diversity High Relative Abundance of Hosts
High Diversity Low Relative Abundance of Hosts
Swaddle and Carlos, 2008. PLoS one 3e2488
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How is our biodiversity doing?
Genetic diversity within species Species
diversity in communities Ecosystem diversity
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How is our biodiversity doing?
Humans used hundreds of crop species worldwide
now 3 species (rice, wheat, corn) provide 60 of
our calories from crop plants. According to the
FAO of the UN, 70 of the genetic diversity of
crop plants has been lost in the last 75 years as
weve shifted to industrial farming and the use
of GM strains.
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How is our biodiversity doing?
2000 Pacific Island bird species (15 of global
total) have gone extinct after human
colonization 20 of the 297 mussel species in
N.A. have gone extinct in the last 100 years 60
are endangered 40 of 950 fish species in N. A.
have gone extinct in the last century 35 are
threatened or endangered http//www.americanscien
tist.org/issues/pub/the-real-biodiversity-crisis/1

Yellow-finned cutthroat trout
http//www.nps.gov/sacn/planyourvisit/st-croix-cur
rents.htm?customel_dataPageID_206517289024
http//www.fishdecoys.net/pages/LDC_Collection/Ben
zieJoDecoys.htm
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How is our biodiversity doing? 1 in 4 mammal
species is endangered 1 in 8 bird species is
endangered 1 in 3 amphibian species is
endangered 48 of primate species are threatened
Data from http//iucn.org/what/tpas/biodiversity
/
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How is our biodiversity doing?
35 of mangrove habitat has been lost in the last
20 years In the Caribbean, hard coral cover has
declined from 50 to 10 in the last 20
years Since 2000, 232,000 sq miles of old growth
forest have been lost (size of Texas).
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WHY?
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7 billion in 2011 (12 years later)
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http//news.mongabay.com/2011/1009-amazon_deforest
ation_revised.html
13,000 sq kilometers is about the size of
Connecticut
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Extent of Virgin Forest, Contiguous U. S.
http//mvh.sr.unh.edu/mvhinvestigations/old_growth
_forests.htm
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Millenium Assessment 2006
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Humans use/control 40 of the food produced on
the planet.
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10 million?
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Habitat loss, Fragmentation, Climate Change
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Fragmentation

Area Effects
CARNIVORES
HERBIVORES
PLANTS
LARGE AREA OF HABITAT
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Fragmentation
HABITAT FRAGMENTATION
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Fragmentation

1. Carnivores lost - (reduce diversity)
2. Herbivores compete (reduce diversity)
3. Plants overgrazed (reduce diversity)

HABITAT FRAGMENTATION
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We are a geological force, operating on an
ecological timescale
Mountaintop removal in West Virginia
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We are a geological force, operating on an
ecological timescale
Gold mining in Peruvian Amazon
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We are a geological force, operating on an
ecological timescale
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We are a geological force, operating on an
ecological timescale
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Sixth major mass extinction event - NOW
All genera
well described genera
The big five Mass Extinction Events
Thousands of Genera
Millions of Years Ago
http//en.wikipedia.org/wiki/FilePhanerozoic_biod
iversity_blank_01.png
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22 May 2010 Secretary-General Ban
Ki-moon Biodiversity loss is moving ecological
systems ever closer to a tipping point beyond
which they will no longer be able to fulfill
their vital functions.
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What Can We Do?
We need to protect and preserve large intact,
biodiverse ecosystems.
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This is great, but it aint gonna do it
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We need to rethink our model of community
nature
nature
Development
Development
Development
Development
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We need to find out whats out there!
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We need to appreciate the societal and economic
value of biodiversity
Corporate Social Responsibility
(CSR) http//www.justmeans.com/Stop-Loss-CSR-Biodi
versity/28856.html Protection of biodiversity
should be the underlying reason for every CSR
effort. Biodiversity loss is the most severe
threat to human-wellbeing on the planet. It rates
even higher than climate change and related
problems. The head of Deutsche Bank's Global
Markets predicts that our current rate of
biodiversity loss could see 6 of global GDP
wiped out as early as 2050. The Economics of
Ecosystems and Biodiversity executive summary
(2010) reports that over 50 of CEOs surveyed in
Latin America and 45 in Africa see declines in
biodiversity as a challenge to business growth.
In contrast, less than 20 of their counterparts
in Western Europe share such concerns
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If we recognize the grandeur of life, we might
appreciate it
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If we appreciate it, we might value it
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If we value it, we might sustain it
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If we sustain it, we might be able to sustain our
societies and economies, as well.
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If we dont, we wont
Thylacine - 1936
Tecopa Pupfish - 1981
Quogga - 1883
Vietnamese Rhinoceros - 2010
Yangtze River Dolphin - 2006
Golden Toad - 1989
A few extinct animal species.
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We abuse land because we regard it as a commodity
belonging to us. When we see land as a community
to which we belong, we may begin to use it with
love and respect. Aldo Leopold - 1949
The last word in ignorance is the man who says
of an animal or plant, What good is it? If the
land mechanism as a whole is good, then every
part is good, whether we understand it or not. If
the biota, in the course of aeons, has built
something we like but do not understand, then who
but a fool would discard seemingly useless parts?
To keep every cog and wheel is the first
precaution of intelligent tinkering.