Dr. Paul A. KeddyThe Development and Use of Assembly Rules in

Predictive Community Ecology

Eva HillmannSpring 2014

Dr. Paul A. KeddyBiography

• b. May 29, 1953 (London, Ontario)

• Canadian ecologist/plant population ecology and community ecology (eastern Canada and Louisiana)

• professor of ecology for 30 years; at University of Guelph(1978-1982), University of Ottawa (1982-1999) and Southeastern Louisiana University (1999-2007)

• 150 peer-reviewed articles, 7 books (author), 2 books (co-editor)

Focus: principles that organize plant communities, with particular emphasis on wetlands

Tactics and strategies for ecological researchKeddy, P.A. 2005. Putting the plants back into plant ecology: six pragmatic models for understanding and conserving plant diversity. Keddy, P. 1994. Reflections on the 21st birthday of MacArthur's Geographical Ecology - applications of the Hertzprung-Russel star diagram to ecology. Keddy, P.A. 1987. Beyond reductionism and scholasticism in plant community ecology.Community assembly rulesKeddy, P.A. 1999. Wetland restoration: the potential for assembly rules in the service of conservation.Weiher, E., I. C. Wisheu, P.A. Keddy and D.R.J. Moore. 1996. Establishment, persistence, and management implications of experimental wetland plant communities.Weiher, E. and P.A. Keddy. 1995. Assembly rules, null models, and trait dispersion: new questions from old patterns.

Competition: gradients & competitive hierarchiesTwolan-Strutt, L. and P.A. Keddy. 1996. Above- and below-ground competition intensity in two contrasting wetland plant communities. Gaudet, C.L. and P.A. Keddy. 1995. Competitive performance and species distribution in shoreline plant communities: a comparative approach.Wilson, S. D. and P.A. Keddy. 1986. Measuring diffuse competition along an environmental gradient: Results from a shoreline plant community. Centrifugal organizationWisheu, I. C. and P.A. Keddy. 1992. Competition and centrifugal organization of ecological communities: theory and tests. Keddy, P.A. and P. MacLellan. 1990. Centrifugal organization in forests.

Coastal plain shoreline vegetation- Nova Scotia & OntarioWisheu, I. C., C. J. Keddy, P.A. Keddy, and N.M. Hill. 1994. Disjunct Atlantic coastal plain species in Nova Scotia: distribution, habitat and conservation priorities.Keddy, P.A. 1985. Lakeshore plants in the Tusket River Valley, Nova Scotia: the distribution and status of some rare species including Coreopsis rosea and Sabatia kennedyana.Keddy, P.A. 1981. Vegetation with Atlantic coastal plain affinities in Axe Lake, near Georgian Bay, Ontario.Great Lakes wetlandsKeddy, P. A. and Reznicek, A. A. (1986). Great Lakes vegetation dynamics: the role of fluctuating water levels and buried seeds. Moore, D.R.J., P.A. Keddy, C.L. Gaudet and I. C. Wisheu. 1989. Conservation of wetlands: do infertile wetlands deserve a higher priority?

Selected Publications and Research Interests

2009 Award of Excellence—Heritage and Ecology, Lanark County 2008 Champion for Nature Award, Mississippi Valley Field Naturalists 2007 National Wetlands Award for Science Research, Environmental Law Institute 2006 Lifetime membership, Society of Wetland Scientists 2006 Merit Award, Society of Wetland Scientists 2005 Team Achievement Award for Louisiana Ecosystem Restoration Study, USACE 2002 Highly Cited Researcher designation by the Institute for Scientific Information (in top 0.5 of 1% of cited scientists in Ecology/Environment worldwide) 1999 Schlieder Endowed Chair for Environmental Studies, Southeastern Louisiana University 1992 Lawson Medal, Canadian Botanical Association 1991 Gleason Prize, New York Botanical Garden Service awards: Committee on the Status of Endangered Wildlife in Canada (1998) Canadian Council on Ecological Areas (1992)

Awards

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

•Context•Assembly rules• Species pools• Environmental filters• Functional traits•Response rules• Deletion rules• Addition rules•Methodological considerations•Mesocosm experiment•Conclusions

Dr. Paul A. Keddy

Focus: principles that organize plant communities, with particular emphasis on wetlands

Context; Central themes and the conceptualization of assembly rules in community ecology•Lewontin 1974•Peters 1991•Lawton 1992•Keddy 1992•Scheiner 1993•Keddy 1993•Scheiner 1994

How are communities assembled from species pools?

Dr. Paul A. Keddy

Focus: principles that organize plant communities, with particular emphasis on wetlands

Can we predict the future states of communities?

Keddy, 1999

Dr. Paul A. Keddy

Focus: principles that organize plant communities, with particular emphasis on wetlands

Can we predict the future states of communities?

Yes!....but we need to sift through the “crap” to identify a few, key general principles

Dr. Paul A. Keddy

Focus: principles that organize plant communities, with particular emphasis on wetlands

•scale and level of organization•variables

Population vs. community ecologyPopulation ecologists predict the properties of aggregations of individuals.Community ecologists predict the properties of aggregations of populations.

Keddy, 1992

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Keddy, 1992

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Assembly rules;The constraints (rules) on community formation and maintenance (assembly)

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Assembly rules;The constraints (rules) on community formation and maintenance (assembly)

3component parts;•species pool•environmental filter•functional trait

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Assembly rules;The constraints (rules) on community formation and maintenance (assembly)Objective;•Predict which subset of total species pool in a region will occur in a specified habitat• Predict presence/absence• Predict abundance

Keddy, 1999

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Environmental filter;•Filter acts on traits unsuitable for the environment•Species that comprise the community survive the filter

Keddy, 1992

assembly rule

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Functional trait;Life history traits that allow organisms to tolerate different filters

Keddy, 1990

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Given•A species pool•A trait matrix•List of environmental filtersAssembly rules would specify which subset of traits (therefore, species possessing them) will persist in a particular habitat

Keddy, 1992 needs more work

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Assembly rules for wetlands;

Keddy, 1992, van der Valk, 1981

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Response rules;•Grow out of assembly rules•Specify how an initial species assemblage will respond when an environmental factor is changed

Different from assembly rules;•Initial vector of species already exists and must predict how these species will respond to change in environmental condition (deletion rules)•Must re-examine species pool and trait maitrix for species likely to replace those presently occurring (addition rules)

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Response rules;

Keddy, 1992

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Methodological considerations;Building trait matrices•requires understanding of key species-environment interactions• Filters likely to operate• Key traits which species possess to protect against filters

•Traits must be measured• Simple (seed size, etc.)• Or complex (growth rate, competitive ability)

•Need to develop bioassay for simple and complex attributes so all species can be screened

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Species or functional groups?•Species can be aggregated into groups sharing similar traits•May be best to start developing assembly/response rules for functional groups•If predicting habitat function is the priority, it may matter little if a functional group is represented by one or several species

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Conclusions;Two clear goals for community ecology;1. Devise efficient research strategies2. Emphasize prediction rather than understanding

Moving forward;•More quantitative relationships between traits and environments

need to be developed and specified•Simple, effective screening techniques for functional traits are

needed•More quantitative approaches to decision rules

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Mesocosm experiment;•Experimental approach to assembly rules•Put standard species pool through a set of environmental filters for their ability to remove species from the species pool and alter community composition•Assumes no dispersal effects

Hypotheses;1. At high fertility Typha would dominate and exclude the

smaller species regardless of treatment type2. Species richness would be greatest in low fertility treatments3. At low fertility, each treatment had greatest liklihood of

forming a distinct community4. Of other treatments, water level would have strongest effect

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Methods;•20 wetland plant species•120 microcosm containers•12 general wetland treatments•2 fertility treatments•5 replicates

Habitat variables;•Water depth•Timing and duration of flooding•Leaf litter•Soil texture•Timing and duration of growing season•Invasion by competitive species

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Results;•As communities developed, abundance increased while species richness decreased•Fertile treatments had higher biomass and lower richness than infertile treatments•Only 2 habitat variables were significant;• Water depth• Fluctuation in water depth

*high water or fluctuations in water level associated with lower species richness

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Keddy, 1995

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Keddy, 1995

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Keddy, 1995

Focus: principles that organize plant communities, with particular emphasis on wetlands

Dr. Paul A. Keddy

Results/Conclusions; •Evidence community composition constrained by assembly rules•Consistent effects of water level, fertility and leaf litter•Some habitat variables had no significant effects•Community assembly can follow different pathways•Convergence on a common endpoint suggests assembly processes are highly constrained

Keddy, P.A. 1999. Wetland restoration: the potential for assembly rules in the service of conservation. Wetlands 19: 716-732.

Weiher, E., G. D. P. Clarke and P.A. Keddy. 1998. Community assembly rules, morphological dispersion, and the coexistence of plant species. Oikos 81: 309-322.

Weiher, E. and P.A. Keddy. 1995. The assembly of experimental wetland plant communities. Oikos 73: 323-335.

Keddy, P.A. 1992. Assembly and response rules: two goals for predictive community ecology. Journal of Vegetation Science 3: 157-164.

Weiher, E. and P. Keddy (eds.) 1999. Ecological Assembly Rules: Perspectives, Advances, Retreats. Cambridge University Press, Cambridge, UK. 418 p.

Keddy, P.A. 1990. The use of functional as opposed to phylogenetic systematics: a first step in predictive community ecology. in S. Kawano (ed.) Biological Approaches and Evolutionary Trends in Plants. Academic Press, London.

Work Consulted

“Asking if there is a pattern in nature is akin to asking if bears shit in the woods.” ---Paul Keddy and Evan Weiher

Questions……….