Warming experiments underpredict plant …Ben Cook & collaborators: J. Allen T. Ault J. Betancourt K...
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Warming experiments underpredict plant phenological responses to
climate change
Elizabeth M. WolkovichUniversity of British Columbia
Ben Cook & collaborators:J. AllenT. AultJ. BetancourtK BolmgrenE. ClelandT. Crimmins J. DaviesN. KraftS. MazerG. McCabeB. McGillC. ParmesanS. PauJ. RegetzM. SchwartzS. Travers
Warming experiments underpredict plant phenological responses to
climate change
Elizabeth M. WolkovichUniversity of British Columbia
Warming by 2099
Changes relative to last 20th century A2 scenario, IPCC, WG1 summary, 2007
How will species respond?
Changes relative to last 20th century A2 scenario, IPCC, WG1 summary, 2007
How will species respond?
Changes relative to last 20th century A2 scenario, IPCC, WG1 summary, 2007
Extinctions
How will species respond?
Changes relative to last 20th century A2 scenario, IPCC, WG1 summary, 2007
Spatial shifts Temporal shifts
Extinctions
Critical predictor & trait:
Critical predictor & trait:
Ties to plant species:
Critical predictor & trait:
Ties to plant species:- Performance
Cleland et. al., in press, Ecology
Critical predictor & trait:
Ties to plant species:- Performance
Cleland et. al., in press, Ecology
- Extinctions
Critical predictor & trait:
Ties to plant species:- Performance
Cleland et. al., in press, Ecology
- Extinctions
- Ranges
Critical predictor & trait:
Ties to plant species:- Performance
Cleland et. al., in press, Ecology
- Extinctions
- Ranges
Controls:- Trophic webs
- Ecosystem functioning
Plant phenology most reported biotic response to climate change
Plant phenology most reported biotic response to climate change
Plant phenology most reported biotic response to climate change
Experiments used for over 20 years
Do experiments and observations predict the same responses to
warming?
Experiments Observations
vs.
Global synthesis of warming effects on plant phenology
Global synthesis of warming effects on plant phenology
Chinnor, UK
Global synthesis of warming effects on plant phenology
Chinnor, UK
Washington, DC
Harvard Forest
Global synthesis of warming effects on plant phenology
experimentsobservations
Common metric for both data types
- Calculated change in days per °C
- Hierarchical mixed-effects models- Accounts for non-
independence among sites and species
Long-term records consistent with other large analyses
mixed-effects model means +/- SE
Long-term records consistent with other large analyses
mixed-effects model means +/- SE
Experiments show smaller effects
Wolkovich et. al., in press, Natureflowering: F1,34 = 9.7, p = 0.004leafing: F1,18 = 2.8, p = 0.1
Experiments show smaller effects
Wolkovich et. al., in press, Nature
1,634 species
flowering: F1,34 = 9.7, p = 0.004leafing: F1,18 = 2.8, p = 0.1
Experiments show smaller effects
Wolkovich et. al., in press, Nature
1,634 species matching species
flowering: F1,34 = 9.7, p = 0.004leafing: F1,18 = 2.8, p = 0.1
Experiments show smaller effects
Wolkovich et. al., in press, Nature
1,634 species matching species
Experiments show smaller effects
1,634 species matching species
binomial tests: flowering & leafing: p = 0.02
Why do experiments underpredict long-term responses?
Difference not due to:
• Species-sampling
• Timescales & genotypic change
• Degree of warming
• Habitat, latitude. . .
Why do experiments underpredict long-term responses?
Why do experiments underpredict long-term responses?
flowering: F2,22 = 7.2; p = 0.004
Species diversity in responses to temperature
Wolkovich et. al., in press, Nature
Species diversity in responses to temperature
Poa annua
Acer saccharum
Wolkovich et. al., in press, Nature
Predicting species’ variation
Predicting species’ variation
• Early-season species
• Annuals vs. perennials
Predicting species’ variation
• Early-season species
• Annuals vs. perennials
Predicting species’ variation
• Early-season species
• Annuals vs. perennials
• Functional traits: Leaf-tissue density
Predicting species’ variation
• Early-season species
• Annuals vs. perennials
• Functional traits: Leaf-tissue density
• No variation with functional groups
Predicting species’ variation
• Early-season species
• Annuals vs. perennials
• Functional traits: Leaf-tissue density
• No variation with functional groups
• Phylogenetic approach
Experiments underpredict phenological responses
to climate change
Experiments Observations
vs.
Conclusions
•Consistent mean response of 5-6 days/˚C
•Warming experiments underpredict 4-8X vs. observations
•Models based on warming experiments should be re-evaluated
AcknowledgementsData managers: David Inouye and George Aldridge (Gothic), Paul Huth, Shanan Smiley, and John Thompson (Mohonk Preserve), John O'Keefe (Harvard), Elisabeth Koch, Wolfgang Lipa and all those who contributed to PEP725 Pan European Phenology Data, Tim Sparks (Marsham), Richard Primack and Abe Miller-Rushing (Concord), F. Stuart Chapin, Niels M. Schmidt, Melissa Martin, Jennifer Dunne, Rebecca Sherry, Xavier Morin, Dustin Bronson and K. Dunnell, Ethel & Gunnar Johansson
Trait data: W. Wen
Photo credits: C. Chen, J. Dukes, C. Kopp, R. Montgomery, N. Sanders
Degree of warming
Davies, et al., in review
Most studies based on long-term records
Marsham
ConcordHarvard Forest
Mohonk
Most studies based on long-term records
Marsham
Most studies based on long-term records
Marsham
Most studies based on long-term records
Marsham
Mohonk
Most studies based on long-term records
Marsham
Concord
Mohonk
Most studies based on long-term records
Marsham
ConcordHarvard Forest
Mohonk