What fraction of species do we need to maintain a functioning ecosystem

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What fraction of species do we need to maintain a
functioning ecosystem?

• Bradley J. Cardinale
• University of California Santa Barbara
• Department of Ecology, Evolution Marine Biology

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Diversity is a byproduct
Common view
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Diversity is a key driver
Complementary view ...
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Seminal experiments
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What have we learned?
Solan et al. (2009)
Key ecological processes increase monotonically
with diversity
Magnitude of diversity effects rival other forms
of environmental change
Processes decelerate and peak at highest
monoculture
Diversity effects are due to complementarity
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Phase II

• Linking pattern to process
• Extending reality
• Towards quantitative predictions

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What fraction of species do we need to maintain a
functioning ecosystem?
Green web
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C
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• 164 experiments
• Manipulated ? 3 species
• 545 diversity effects on
• Resource capture
• Biomass production

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Brown web
Cardinale et al., Ecology (2009)
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Methods
y Resource capture
or
y Biomass production
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Biomass production (N 127)
Resource capture (N 75)
? 70 of ymax
Number of studies

? 80 of ymax
? 90 of ymax
1.0
1.0
0.01
0.10
10
0.01
0.10
10
Proportion of species required, S/Smax
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What fraction of species do we need to maintain a
functioning ecosystem?
Green web
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Brown web
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But
lt 1 generation
gt 1 generation
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ymax
K
Time scale ln(generations)
Spatial scale ln(area or volume / body size)
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But
Now
lt 1 generation
gt 1 generation
ymax 0.02ln(Time) 0.17ln(Space)
K 0.11ln(Time) 0.17ln(Space)
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Biomass production (N 127)
Resource capture (N 75)
0.13
0.18
? 70 of ymax
0.30
0.22
Number of studies

? 80 of ymax
0.68
0.49
? 90 of ymax
1.0
1.0
0.01
0.10
10
0.01
0.10
10
Proportion of species required, S/Smax
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What fraction of species do we need to maintain a
functioning ecosystem?
Green web
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Brown web
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But
Why?
lt 1 generation
gt 1 generation
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(No Transcript)
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lt 1 generation
gt 1 generation
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What fraction of species do we need to maintain a
functioning ecosystem?
Experiments 13-50 of species needed to maintain
70-90 function
Scaling relationships 5-10x the maximum number of
species used in experiments
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Acknowledgements
Lab members Lindsey Albertson, Josie Hardy,
Lauren Koenig, Konrad Kulacki, Carolyn Kurle,
Kristin Matulich
Other collaborators Marc Cadotte, Ian Carroll,
Amy Downing, Emmett Duffy, Andy Hector, Claire
Jouseau, Michel Loreau, Mahesh Sankaran, Diane
Srivastava, J.J. Weis, Justin Wright
Funding
Talk available at www.lifesci.ucsb.edu/eemb/labs/c
ardinale/index.html
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But
Why?
A
B
C
F
E
D
lt 1 generation
gt 1 generation
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What have we learned?
Solan et al. (2009)
Key ecological processes increase monotonically
with diversity
Magnitude of diversity effects rival other forms
of environmental change
Processes decelerate and peak at highest
monoculture
Diversity effects are due to complementarity
Balvanera et al., Ecol Lett (2006), Cardinale et
al., Nature (2006), Cardinale et al., PNAS 2007,
Schmid et al. (in press)
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Diversity is a key driver
Complementary view ...