1. The document describes tools for modeling the effects of climate change on plant distributions, including a spline climate model for predicting climate variables and models for relating plant species distributions to climate profiles and predicting future distributions under climate change scenarios.
2. Examples are given of modeling the distributions of species like Douglas-fir, western larch, and bluebunch wheatgrass under current and future climates according to climate change scenarios.
3. The author acknowledges the models predict species distributions better than expected but that the overall effects of climate change on vegetation will be disruptive at multiple levels and species may not track their climate profiles as predicted.
2. Acknowledgements
• Jerry Rehfeldt
• Marcus Warwell
• Nick Crookston
• Jeff Evans
• Bryce Richardson
3. Tools to help model the effects of
climate change
1. Predict climate variables
2. Use climate variables to predict plant
species distributions
3. Link predicted climate to climate change
scenarios
4. 1. Predicting climate
• Spline climate model by Jerry Rehfeldt
(2006)
– Based on monthly normals from 1961 – 1990
– Used ~6,000 weather stations from western
U.S. and Canada
– Latitude, longitude, and elevation
– 18 derived climate variables
– Average R-square was 0.95
– Maps in this presentation are 1 km² resolution
7. Climate variables derived from temperature
and precipitation monthlies
• Mean annual temperature • Degree-days > 5 °C
• Mean annual precipitation • Degree-days < 0 °C
• Growing season precipitation • Frost-free period
• Mean cold month temperature • Last spring frost
• Minimum cold month
• First fall frost
temperature
• Mean warm month temperature • Growing season degree-
days > 5 °C
• Maximum warm month
temperature • Summer-winter
• Annual dryness index temperature differential
• Summer dryness index • Date degree-days > 5 °C
• Minimum degree-days <0 °C reaches 100
8. 2. Use contemporary climate to predict
current plant communities and species
distributions
• Model “climate profile”
9. Rehfeldt, Crookston,
Warwell and Evans.
2006. Empirical analysis
of plant-climate
relationships for the
western United States.
IJPS 167:1123–1150
Brown’s 26
biotic
communities
10.
11.
12. The problem with ecosystem models:
• Individual plants, not communities, respond
to climate
• Species have different physiologies and will
respond differently
13. Let’s look at some individual plant species
• Predictions for contemporary climate
• Comparison to range maps of Little (1971)
• Used 118,000 plots westwide
14. Douglas-fir,
contemporary
climate
(1961 - 1990)
Yellow:
50 to 75%
confidence
Red:
75 to 100%
confidence
18. Saguaro
cactus,
contemporary
climate
Yellow:
50 to 75%
confidence
Red:
75 to 100%
confidence
19. 3. Use climate change scenarios to
predict future species distributions
We used a 1% increase per year in greenhouse
gasses (Hadley Center and Canadian Center), a
relatively conservative scenario
51. Potential impact on the vegetation?
disruption at all levels of organization
• maladaptation of populations
• shifts in species distributions
• realignment of ecosystems
Bottom line:
To have future forests like those of today, the
proper genotypes of the best-suited species
must arrive somewhere near the future
location of their climatic optima
55. Conclusions
1. Predictions of species climate profiles
were much better than we expected
2. We show a technique for predicting
effects of climate change
3. We do not know “the” answer
4. See if various approaches produce the
same results
56. Rehfeldt et al., 2006
Plant-climate relationships paper
http://www.treesearch.fs.fed.us/pubs/25706
Get jpeg illustrations
and ASCII grids at:
http://forest.moscowfsl.wsu.edu/climate
