Tree rings and drought on the Canadian Prairies
I've been asked to give a presentation at a workshop to be held in Alberta in March. The workshop will revolve mainly around the use of tree rings and other natural 'proxy' records to water issues in the Canadian Prairie provinces.
I'll be presenting material drawn from the last chapter of my doctoral dissertation, and will talk about the strengths and limitations of tree-ring records as indicators of past drought. The audience will include between 50 and 100 water managers from the region, and for many of them, the workshop will be their first exposure to tree rings and other forms of paleoclimatology. I think it will be in their best interest (and mine) that the scientific presentations focus more on big-picture ideas and less on technical details and methodology.
With an eye towards getting my point across more effectively, I've worked up a set of slides in the 'Presentation Zen' style. I've included more photos than I have in previous presentations, and have also tried to swap out complex journal-style diagrams and replace them with simpler graphics.
I'm excited (and a little nervous) to see how the presentation is received - I imagine its style will be quite different from the other talks in the workshop. I've posted the slides at Slideshare.net, and would appreciate any comments or suggestions - the workshop is not for another six weeks, so I have plenty of time left to tweak or change my plans.
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Slideshow Transcript
- Slide 1: Tree Rings and Drought Past drought on the Canadian Prairies S co tt St. Ge orge Geological Survey of Canada
- Slide 2: Prairie tree-ring network, ca. 1996
- Slide 3: 3
- Slide 5: Fort Dufferin, Manitoba
- Slide 6: 4,000 year-old river logs 6
- Slide 7: Prairie tree-ring network Northern Saskatchewan Eastern Rockies Northwestern Ontario Southern Manitoba
- Slide 8: 4 Characteristics of Prairie tree rings
- Slide 9: The tree-ring record of summer drought in the Canadian Prairies Scott St. George David Meko Greg Pederson Martin-Phillippe Girardin David Sauchyn Glen MacDonald Jacques Tardif Erik Nielsen Emma Watson Submitted to the Journal of Climate, January 2008
- Slide 10: Tree age
- Slide 11: Bristlecone pine 4,844 years Source: OLDLIST Photo: Tom Harlan
- Slide 12: Eastern white cedar 1,653 years Source: OLDLIST Photo: Peter Kelly
- Slide 13: Eastern white pine 290 years Source: M. Girardin
- Slide 14: Bur oak 279 years
- Slide 15: Limber pine 846 years Source: G. Pederson Photo: Greg Pederson
- Slide 16: Richard I of England 16 Photo: julie & fanu
- Slide 17: Length of regional records S. Alberta 480 N. Saskatchewan 169 S. Manitoba 485 NW Ontario 225 0 125 250 375 500 Years
- Slide 18: Seasonality
- Slide 19: “ The trees composing the forest rejoice and lament with its successes and failures and carry year by year something of its story in their annual rings. ”Douglass A.E.
- Slide 20: Dominant seasonal signals 90 82 80 70 60 50 Sites 40 30 24 20 10 7 3 0 20 Autumn Winter Spring Summer Autumn
- Slide 21: 21
- Slide 22: 22
- Slide 23: Medicine Hat, Alberta Source: Environment Canada, Adjusted Historical Canadian Climate Data, 1895 – 2006
- Slide 24: 24
- Slide 25: Effectiveness
- Slide 26: Dendrohydrology works best where it’s dry ...
- Slide 27: and not so well where it’s wet
- Slide 28: Ringwidth as a proxy for ‘Lethbridge’ PDSI
- Slide 29: Ringwidth as a proxy for ‘Dryden’ PDSI
- Slide 30: Uncertainty
- Slide 31: 755 m3/s 847 m3/s 809 m3/s 770 m3/s 823 m3/s 787 m3/s 901 m3/s 3
- Slide 32: “Trees are not thermometers or raingauges.” Keith Briffa and colleagues
- Slide 33: Quantitative drought estimates
- Slide 34: Quantitative drought estimates
- Slide 35: Can we Absolutely! do better?
- Slide 36: Photo: Emma Watson
- Slide 38: Photo: New York Times 38
- Slide 39: Focus on long-term drought 100% 60% 43% Explained variance 75% 50% 57% 40% 25% 0% Single Year 5-Year Average
- Slide 40: Courtesy Keith Lombardo Measure other stuff Wood chemistry Wood density Stable isotopes Wood anatomy
- Slide 41: Prairie tree rings & drought 41
- Slide 42: Photo: Monceau web.mac.com/scottstgeorge
