B' Diversity

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B. Diversity 3. Relationships with
Productivity a. Productivity increases
diversity b. Diversity increases
productivity - Sampling Effects More diverse
communities are more likely to contain the most
productive species, and thus raise the total
productivity.
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B. Diversity 3. Relationships with
Productivity a. Productivity increases
diversity b. Diversity increases
productivity - 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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B. Diversity 3. Relationships with
Productivity a. Productivity increases
diversity b. Diversity increases
productivity - 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 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.
8

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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- 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 3. The effects were
non-additive there were more arthropods (and
herbivores and predators) in 6 and 12 species
plots than predicted by adding the richness
values of the monocultures.
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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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VI. Productivity, Diversity, and Stability A.
Productivity B. Diversity C. Stability
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C. Stability 1. Types
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C. Stability 1. Types - "resistance to
change"
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C. Stability 1. Types - "resistance to
change" - "resilience after change"
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C. Stability 1. Types 2. Relationships with
diversity
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C. 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. 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. monoculture - sensitive to one
pest Diversity increases resistance
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C. Stability
Biodiversity and Ecosystem Functioning Current
Knowledge and Future Challenges. Loreau, et al.
2001. Science 294 804 - 808
As richness increases, communities 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....
REDUCE RAINFALL... REDUCE NUTRIENTS INCREASE FIRE
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RAINFOREST (wet, few fires)
"Multiple Stable States"
GRASSLAND (dry, many fires)
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VI. Productivity, Diversity, and Stability A.
Productivity B. Diversity C. Stability D.
Summary
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D. Summary 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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D. Summary (We don't want "boom and bust",
"feast and famine" scenarios....)
FEAST
FAMINE
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D. Summary 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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D. Summary 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
DIVERSITY ..... right......
PRODUCTIVITY
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D. Summary 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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de Ruiter et al. 2005. Food Web Ecology Playing
Jenga and Beyond Science 30968 - 71