Download Biodiversity and Ecosystem Function

Biodiversity and
Ecosystem
Function
Ecosystems Ecology
April 9th, 2014
Biodiversity loss and its impact
on humanity
Bradley J. Cardinale, J. Emmett Duffy,
Andrew Gonzalez, David U. Hooper, Charles
Perrings, Patrick Venail, Anita Narwani,
Georgina M. Mace, David Tilman, David
A.Wardle, Ann P. Kinzig, Gretchen C. Daily,
Michel Loreau, James B. Grace, Anne
Larigauderie, Diane S. Srivastava & Shahid
Naeem
Nature Review- June 2012
Biodiversity
 The
variety of life
 Variation among species, functional traits
and genes
 Measured as:

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
Richness- the number of unique life forms
Evenness- the equitability among life forms
Heterogeneity- dissimilarity among life forms
 Phylogeny
Distance
Ecosystem Function
 Ecological
processes that control the
fluxes of energy, nutrients and organic
matter through an environment
 Examples include:


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
Primary production
Nutrient cycling
Decomposition
Habitat building
 Assume
this is related to biodiversity
BEF Questions
 Is
there more plant biomass in a more
diverse or less diverse plot of land?
 Do diverse forest store more carbon than
less diverse forests?
 Can a stream clean up more pollution if it
has a more diverse microbial community
vs. a less diverse microbial community?
 Do more diverse fisheries provide more
food than less diverse fisheries?
Biodiversity Research at Cedar
Creek
https://www.youtube.com/watch?v=Wmqy
Y4BXJaI
Six Consensus Statements
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Loss of biodiversity reduces ecosystem
functions
Biodiversity enhances ecosystem stability
BEF relationship is positive and decelerating
Biodiversity increases ecosystem function
through the sampling effect and
complementarity
Trophic interactions are important to the BEF
relationship
Which species are lost matters to ecosystem
function
Consensus Statement One
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
Loss of biodiversity reduces ecosystem function
Biodiversity ↓

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
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
Loss of biodiversity can be:


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Capture of resources ↓
Biomass production ↓
Decomposition ↓
Nutrient recycling ↓
Genes
Species
Functional groups
There are exceptions to this general statement
Evidence of BEF relationship
and exceptions
O’Connor and Byrnes 2013
Consensus Statement Two


Biodiversity increases stability of ecosystem
functions over time
Mechanisms enhancing stability:
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

Over-yielding: mean biomass increases with
diversity more rapidly than its standard deviation
Statistical averaging: random variation in the
abundances of different species reduces the
variability of aggregate ecosystem variables
Compensatory dynamics: competitive interactions
and/or differential responses to environmental
fluctuations among different species leads to
asynchrony in their response to the environment
Statistical Averaging
O’Connor and Byrnes 2013
Compensatory Dynamics
Lennon and Jones 2011
Consensus Statement Three
 Relationship
between biodiversity and
ecosystem function:



Positive
Nonlinear
Saturating
 Initial
losses of biodiversity has relatively
small impacts, but increasing losses lead
to accelerating decrease in function

Do not know inflection point
BEF Relationship
Positive,
nonlinear,
decelerating
curve
with asymptote
Cardinale et al 2011
Consensus Statement Four
 Mechanisms


behind BEF relationship:
Sampling effect: increased biodiversity
increases chances of including highly
productive species
Complementarity: coexisting species either
positively interact or use different resources/
niches and therefore use resources more
completely
Sampling Effect
Tilman et al 1997
Complementarity: Niche
Partitioning
Tilman et al 1997
A Tale of Two Urchins
http://www.nytimes.com/video/science/10
0000002735051/creaturecast-a-tale-of-twourchins.html?playlistId=100000002438160
Consensus Statement Five
 Loss
of diversity across trophic levels has
the potential to influence ecosystem
functions even more strongly than
diversity loss within trophic levels
 Food web interactions are key mediators
of ecosystem functioning
 Loss of higher consumers can cascade
through a food web to influence plant
biomass
Trophic Levels and Biodiversity
Loss
O’Connor and Byrnes 2013
Trophic Levels and Biodiversity
Loss
Jackson et al 2001
Consensus Statement Six
 There
is considerable variation in the
relationship between biodiversity and
ecosystem function

Some of this variability comes from
differences in the identity of the organisms
and their functional traits
 To
predict the consequences of extinction
we must know which species have
greatest extinction risk and how the traits
of those organisms influence function
Random vs. Ordered Loss
O’Connor and Byrnes 2013
Four Emerging Trends
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Biodiversity loss may be as large an
environmental threat as climate change
Biodiversity loss may have a larger impact
when examined on larger spatial and
temporal scales
More biodiversity is needed to maintain
multiple functions than is needed to maintain
a single function
Phylogenetic diversity may be an important
measure of biodiversity
Emerging Trend One
 The
impacts of biodiversity loss might be
sufficiently large to rival the impacts of
many other global drivers of
environmental change
 Because the BEF relationship is nonlinear
the exact ranking of diversity relative to
other drivers will depend on the
magnitude of biodiversity loss, as well as
magnitudes of other environmental
changes
Diversity Loss vs. Environmental
Change
Tilman et al 2012
Emerging Trend Two

Diversity effects are stronger:
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Over longer time scales
With larger spatial scales
Diversity effects in small-scale, short-term
experiments may underestimate the impacts
of diversity loss on the functioning of more
natural ecosystems
More environmental heterogeneity may
increase opportunities for species to exploit
more niches
Increased Biodiversity Effect
Over Time
Tilman et al 2001
Emerging Trend Three
 Maintaining
multiple ecosystem
processes at multiple places and times
requires higher levels of biodiversity than
does a single process at a single place
and time
 Organisms that control ecological
processes at any single location, or in any
particular year, often differ from those
that control processes in other locations or
years
Biodiversity and ecosystem
multifunctionality
Hector and Bagchi 2007
Emerging Trend Four
 The
ecological consequences of
biodiversity loss can be predicted from
evolutionary history
 Species contain genetic and trait
variation that is shaped by patterns of
ancestry
 Phylogenetic distances among species
may explain more variation in biomass
production than taxonomic diversity
Importance of Phylogenetic
Diversity
Flynn et al 2011
Ecosystem Services
 The
suite of benefits that ecosystems
provide to humanity
 Two types of ecosystem services


Provisioning- involve the production of
renewable resources
Regulating- services that lessen
environmental change
What does biodiversity do for
us?
https://www.youtube.com/watch?v=eIk1VVgQvo
Four BES Statements
 Biodiversity
is often associated with
increased ecosystem services
 Biodiversity can have a mixed association
with ecosystem services
 For many ecosystem services there is a
lack of evidence relating its relationship to
biodiversity
 Biodiversity can have a negative
association with ecosystem services
Statement One
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
Biodiversity directly influences or is strongly
correlated with certain provisioning and
regulating services
Most of these services can be directly linked
to the ecosystem functions measured in BEF
experiments
For services less tightly linked to ecosystem
functions, we often lack rigorous verification
of the diversity–service relationship
Biodiversity and Ecosystem
Service
Cardinale et al 2011
Statement Two
 For
many ecosystem services the
evidence for effects of biodiversity is
mixed
 Important opportunities exist for new
research to assess the factors that control
variation in the response of these services
to changes in biodiversity
Biodiversity and Ecosystem
Service
Cardinale et al 2012
Statement Three
 For
many services there are insufficient
data to evaluate the relationship between
biodiversity and ecosystem service
 This may be attributable to different uses
of the term biodiversity
 This emphasizes the need for stronger and
more explicit evidence to back up claims
for biodiversity effects on ecosystem
services
Statement Four
 For
a small number of ecosystem services,
current evidence for the impact of
biodiversity runs counter to expectations
 There are instances where increased
biodiversity may be deleterious
 Cautions against making sweeping
statements that biodiversity always brings
benefits to society
Biodiversity and Ecosystem
Service
Cardinale et al 2012