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Ecosystem Ecology
I. Introduction
II. Energy Flow
III. Biogeochemical Cycles
IV. Productivity, Diversity, and Stability
A. Productivity
A. Productivity
1. Gross Primary Productivity?
A. Productivity
1. Gross Primary Productivity
Total photosynthetic productivity;
CO2 + H20 -----> Glucose + O2
A. Productivity
2. Net Primary Productivity?
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.)
B. Diversity - Relationships with Productivity
B. Diversity - Relationships with Productivity
1. Productivity increases diversity
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.
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.
B. Diversity - Relationships with Productivity
1. Productivity increases diversity
2. Diversity increases productivity
- Sampling Effects
More diverse communities are more likely to
contain the most productive species, and thus
raise the total 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
Monoculture
They all need the same
things at the same
concentrations; have to
place them far apart to
reduce competition.
Polyculture
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.
- Positive Interactions
More diverse communities may contain
species that benefit other species, and thus
increase the productivity of the whole
community
Monoculture
They all need the same
things at the same
concentrations; have to
place them far apart to
reduce competition.
Polyculture
Nitrogen fixing legumes
(beans) nutrify the soil,
increasing the growth of
other plants
without
beans
with
beans
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
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.
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
(can’t just be
sampling
effect).
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
complementa
rity in natural
systems…
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 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”)
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).
Additional Experiments and Results:
- Greater plant species numbers led to
greater ecosystem stability (lower year-toyear variation in total plant biomass) but to
lower species stability (greater year-to-year
variation in abundances of individual
species).
Additional Experiments and Results:
- Stored soil carbon increases with diversity.
- 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.
- Example Crutsinger, et al. 2006.
Science 313: 966-968.
Results:
1: ANPP correlated with number
of genotypes in plot.
- 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.
- 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.
- 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).
- 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).
- 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.
- Example Crutsinger, et al. 2006. Science 313: 966-968.
Conclusions:
ANPP increased with genetic diversity, probably as a function of niche
complementarity.
- 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.
- 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 speciesrich communities.
C. Effects on Stability
C. Effects on Stability
1. Types
- "resistance to change"
- "resilience after change"
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.
C. Effects on 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).
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
Stimulate condensation
and precipitation
Volatiles released
Rainforests feed
themselves and
water themselves.
Decomposition
rapid
Absorption rapid
CUT FOREST
DOWN
Select for fire-adapted
grasses.... rainforest
doesn't come back....
REDUCE RAINFALL...
REDUCE NUTRIENTS
INCREASE FIRE
RAINFOREST
(wet, few fires)
"Multiple
Stable States"
GRASSLAND
(dry, many fires)
We are dependent on the environment
for food and resources. Ideally, we
would like a STABLE, PRODUCTIVE
supply of these resources.... right??
FEAST
FAMINE
(We don't want "boom and bust", "feast
and famine" scenarios....)
FEAST
FAMINE
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
We are playing jenga with our life
support systems...
de Ruiter et al. 2005. Food Web
Ecology: Playing Jenga and
Beyond Science 309:68 - 71
de Ruiter et al. 2005. Food Web Ecology: Playing Jenga and Beyond Science
309:68 - 71
“The pale blue dot” …. Earth from the Voyager spacecraft, > 4 billion miles away
http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=2148
http://www.solstation.com/stars/earth.htm
http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-mars.html
http://www.thew2o.net/#
http://www.misterteacher.com/rainforestwebquest.html
CO2
N2
H2O
Ar
Earth
Mars
0.035%
77%
1%
0.93%
95%
2.7%
0.007%
1.6%
O2
http://www.misterteacher.com/rainforestwebquest.html
21%
trace
http://science.kennesaw.edu/~jdirnber/BioOceanography/Lectures/LecPhysicalOcean/LecPhysicalOcean.html
0.5 bya: Cambrian
0.24 bya:Mesozoic
0.065 bya:Cenozoic
0.9 bya: first animals
1.8 bya: first eukaryote
2.3-2.0 bya: Oxygen
4.0 bya: Oldest Rocks
3.4 bya: Oldest Fossils
4.5 bya: Earth Forms
Earth History
4.5 million to present
(1/1000th of earth
history)
All genera
The “big five” Mass Extinction Events
Millions of Years Ago
http://en.wikipedia.org/wiki/File:Phanerozoic_biodiversity_blank_01.png
Thousands of Genera
“well described” genera
(% of Genera)
Permian mass extinction: 96% of all marine species and 70% of
terrestrial vertebrate species
WHY?
WHY?
WHY?
WHY?
WHY?
http://science.nationalgeographic.com/science/prehistoric-world/mass-extinction/
ecological
collapse
Almost all animals
over 25kg (~55 lbs)
went extinct.
(The things that require the most
energy to survive)
http://we.vub.ac.be/~dglg/Web/Claeys/Chicxulub/Chixproject.html
BIODIVERSITY NOW
http://www.coral.org/node/3230
Millenium Ecosystem Assessment (2006)
http://englishontour.blogspot.com/2011/03/beetles.html
http://www.illuminatedorigin.com/The_Illuminated_Origin_of_Species/Blog/Entries/2011/9/22_Beetles!.html
Detritivores
Pollinators
Insect predators
Herbivores
http://www.sbs.utexas.edu/jcabbott/abbottlab/
http://www.dendroboard.com/forum/photography/42636-incredible-costa-rican-euglossine-bees.html
Pollinators
Insect Parasitoids (lay eggs on other insects)
Insect Predators
http://magicbelles.com/flutterbudclub/special-wonders/beetles
Jewel Bug
Herbivores
Pollinators
Parasites
Detritivores
Malagasy Sunset Butterfly
http://www.brisbaneinsects.com/brisbane_flies/images/PWC_8410.jpg
http://buggirl.tumblr.com/post/12568644622/bugs-that-break-the-rules-themadagascar-sunset
http://www.trekearth.com/gallery/Africa/South_Africa/West/Eastern_Cape/Kob_Inn/photo915391.htm
Herbivores
Detritivores
http://www.flowersociety.org/Redwood-profile.htm
PRODUCERS
http://www.paulsanghera.com/infonential-Contact.html
Most vertebrate species are fishes
http://www.elp.manchester.ac.uk/pub_projects/2003/MNZO0MLK/lecture1.htm
http://ambergriscaye.com/critters/redeyedtreefrog.ht
ml
http://australian-animals.net/plat.htm
http://freakz.info/2011/09/21/10-interesting-seahorse-facts/
http://www.pbase.com/image/37557333
http://www.bbc.co.uk/nature/life/Blue_Whale
Herbivores, Predators, Detritivores, Pollinators
http://www.hodag.info/what%E2%80%99s-going-on-herethen-100
But do we
NEED all these
species??
There’s a lot of redundancy in nature…
http://katherinegerdes.com/portfolio/11/rainy-day-jewels
Are all species equally important? If not, which ones are critical?
with
without
We don’t know
which species
are critical
So we need to
save them all to
maintain
ecosystem
function
But what does
biodiversity
do??
1) Biodiversity increases “productivity” ... FOOD
Monoculture
They all need the same things at
the same concentrations; they
compete.
“Niche Complementarity”
Monoculture
Polyculture
They all need the same things at Combinations of different plants can be
the same concentrations; they
planted at higher density, and they use
compete.
different "niches" and coexist. Even if
abundance of "most productive" species
drops, this loss can be offset.
“Positive Effects”
Monoculture
They all need the same things at
the same concentrations; they
compete.
Polyculture
without
beans
with
beans
Nitrogen fixing legumes (beans) nutrify
the soil, increasing the growth of other
plants. And you have beans!
2) Biodiversity
improves
ecosystem
services
Estimates of various Ecosystem Services $U.S. trillions
Ecosystem services
Value
(trillion $US)
Soil formation
Recreation
Nutrient cycling
Water regulation and supply
Climate regulation
(temperature and
precipitation)
Habitat
Flood and storm protection
Food and raw materials
production
Genetic resources
Atmospheric gas balance
Pollination
All other services
Total value of ecosystem
services
17.1
3.0
2.3
2.3
1.8
1.4
1.1
0.8
0.8
0.7
0.4
1.6
33.3
Source: Adapted from R. Costanza et al., “The
Value of the World’s Ecosystem Services and
Natural Capital,” Nature, Vol. 387 (1997), p. 256,
Table 2.
TOTAL GLOBAL GNP (1997) = 18 trillion.
3) Aesthetics and
Inspiration: Biodiversity
enriches our cultures
3) Aesthetics and
Inspiration: Biodiversity
enriches our cultures
How is our biodiversity doing?
Genetic diversity within species
Species diversity in communities
Ecosystem diversity
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 we’ve shifted to industrial farming and the
use of GM strains.
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.americanscientist.org/issues/pub/the-real-biodiversity-crisis/1
Yellow-finned cutthroat trout
http://www.fishdecoys.net/pages/LDC_Collection/BenzieJoDecoys.htm
http://www.nps.gov/sacn/planyourvisit/st-croixcurrents.htm?customel_dataPageID_206517=289024
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/
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).
WHY?
7 billion in 2011 (12 years later)
http://news.mongabay.com/2011/1009-amazon_deforestation_revised.html
13,000 sq kilometers is about the size of Connecticut
Extent of Virgin Forest, Contiguous U. S.
http://mvh.sr.unh.edu/mvhinvestigations/old_growth_forests.htm
Millenium Assessment 2006
Humans use/control
40% of the ‘food’
produced on the
planet.
1
10 million?
Fragmentation
Fragmentation
Area Effects
CARNIVORES
HERBIVORES
PLANTS
LARGE AREA OF HABITAT
Fragmentation
HABITAT FRAGMENTATION
Fragmentation
1)Carnivores lost - (reduce diversity)
2)Herbivores compete – (reduce diversity)
3)Plants overgrazed – (reduce diversity)
HABITAT FRAGMENTATION
We are a geological force, operating
on an ecological timescale
Mountaintop removal in West Virginia
We are a geological force, operating
on an ecological timescale
Gold mining in Peruvian Amazon
We are a geological force, operating
on an ecological timescale
We are a geological force, operating
on an ecological timescale
We are a geological force, operating
on an ecological timescale
Hmmmm….
Sixth major mass extinction event - NOW
All genera
The “big five” Mass Extinction Events
Millions of Years Ago
http://en.wikipedia.org/wiki/File:Phanerozoic_biodiversity_blank_01.png
Thousands of Genera
“well described” genera
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.”
What Can We Do?
We need to protect and
preserve large intact,
biodiverse ecosystems.
This is great, but it ain’t gonna do it…
We need to rethink our model of community…
nature
nature
Development
Development
Development
Development
We need to find out what’s out there!
We need to appreciate the societal and
economic value of biodiversity
Corporate Social Responsibility (CSR)
http://www.justmeans.com/Stop-Loss-CSR-Biodiversity/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”
If we recognize the grandeur of life, we might
appreciate it…
If we appreciate it, we might value it…
If we value it, we might sustain it…
If we sustain it, we might be able to sustain our societies
and economies, as well.
ECONOMY
SOCIETY
ENVIRONMENT
If we don’t, we won’t…
Thylacine - 1936
Tecopa Pupfish - 1981
Quogga - 1883
Vietnamese Rhinoceros - 2010
Yangtze River Dolphin - 2006
Golden Toad - 1989
A few extinct animal species.