Biodiversity and Ecosystem Functionbiol336-bowen.wikispaces.umb.edu/file/view/Ecosystems Ecology-...
Transcript of Biodiversity and Ecosystem Functionbiol336-bowen.wikispaces.umb.edu/file/view/Ecosystems Ecology-...
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:
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: 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=WmqyY4BXJaI
Six Consensus Statements 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 Loss of biodiversity reduces ecosystem function Biodiversity ↓
Capture of resources ↓ Biomass production ↓ Decomposition ↓ Nutrient recycling ↓
Loss of biodiversity can be: Genes Species Functional groups
There are exceptions to this general statement
Consensus Statement Two Biodiversity increases stability of ecosystem
functions over time Mechanisms enhancing stability:
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
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
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
A Tale of Two Urchins http://www.nytimes.com/video/science/100000002735051/creaturecast-a-tale-of-two-urchins.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
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
Four Emerging Trends 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
Emerging Trend Two Diversity effects are stronger:
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
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
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
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=e-Ik1VVgQvo
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 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
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
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