Biodiversity and Ecosystem Function

1. Biodiversity and Ecosystem Function Ecosystems Ecology April 9th, 2014

2. 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 & ShahidNaeem Nature Review- June 2012

3. 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

4. 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

5. 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?

6. Biodiversity Research at Cedar Creek https://www.youtube.com/watch?v=WmqyY4BXJaI

7. 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

8. 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

9. Evidence of BEF relationship and exceptions O’Connor and Byrnes 2013

10. 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

11. Statistical Averaging O’Connor and Byrnes 2013

12. Compensatory Dynamics Lennon and Jones 2011

13. 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

14. BEF Relationship Positive, nonlinear, decelerating curve with asymptote Cardinale et al 2011

15. 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

16. Sampling Effect Tilman et al 1997

17. Complementarity: Niche Partitioning Tilman et al 1997

18. A Tale of Two Urchins http://www.nytimes.com/video/science/100000002735051/creaturecast-a-tale-of-two-urchins.html?playlistId=100000002438160

19. 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

20. Trophic Levels and Biodiversity Loss O’Connor and Byrnes 2013

21. Trophic Levels and Biodiversity Loss Jackson et al 2001

22. 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 riskand how the traits of those organisms influence function

23. Random vs. Ordered Loss O’Connor and Byrnes 2013

24. 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

25. 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

26. Diversity Loss vs. Environmental Change Tilman et al 2012

27. 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

28. Increased Biodiversity Effect Over Time Tilman et al 2001

29. 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

30. Biodiversity and ecosystem multifunctionality Hector and Bagchi 2007

31. 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

32. Importance of Phylogenetic Diversity Flynn et al 2011

33. 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

34. What does biodiversity do for us? https://www.youtube.com/watch?v=e-Ik1VVgQvo

35. 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

36. Statement One • Biodiversity directlyinfluences 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

37. Biodiversity and Ecosystem Service Cardinaleet al 2011

38. Statement Two • For many ecosystem services the evidence for effects of biodiversity is mixed • Importantopportunities exist for new research to assess the factors that control variation in the response of these services to changes in biodiversity

39. Biodiversity and Ecosystem Service Cardinaleet al 2012

40. 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

41. 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

42. Biodiversity and Ecosystem Service Cardinaleet al 2012