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A dendrochronological assessment of climate on the Fraser Plateau, British Columbia

A dendrochronological assessment of climate on the Fraser Plateau, British Columbia. Ze’ev Gedalof, Robert Au, Brett Blundon, Gunnar Carnwath, Pete Clark, Jeffrey Kane, Suzan Lapp, Stockton Maxwell, Mauricio Morena, Mike Tjoelker, Jessica Vanstone. Hypotheses.

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A dendrochronological assessment of climate on the Fraser Plateau, British Columbia

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  1. A dendrochronological assessment of climate on the Fraser Plateau, British Columbia Ze’ev Gedalof, Robert Au, Brett Blundon, Gunnar Carnwath, Pete Clark, Jeffrey Kane, Suzan Lapp, Stockton Maxwell, Mauricio Morena, Mike Tjoelker, Jessica Vanstone

  2. Hypotheses 1) Is tree ring growth limited by moisture availability? 2) Are earlywood and latewood ring widths effected by different climatic signals? 3) Are the relationships between tree ring growth and climate stable over time? 4) Do tree ring widths predict large-scale climate anomalies (eg. ENSO, PDO)? 5) Do large-scale circulations influence tree ring growth?

  3. Study Site • Dominant overstory • Douglas-fir (PSME) • Ponderosa pine (PIPO) • Olalla Creek • South facing slope • Elevation 750 m

  4. Methods Field Sampling • 20 trees for each species -- PSME, PIPO • 2 cores per tree • Target sampled mature trees Core Processing • Mounted all samples • Sanded samples to 400 grit

  5. Methods Core Analysis • Scanned all cores (800+ dpi) • Dated and measured cores using WinDendro • Verified crossdating using COFECHA Black lines represent ring boundaries Green lines represent earlywood to late wood boundaries

  6. Methods Detrending • Removed age-related growth patterns using a negative exponential function (ARSTAN) Detrending Single Sample Residual ARSTAN Sample Depth

  7. Climate Information • Climate data from Summerland, BC Weather Station

  8. Results... Take it and like it! Chronology Statistics Ponderosa pine chronology • 17 series, 12 trees • Mean Sensitivity: 0.32 • Chronology Length: 1750-2007 • Inter-series correlation: 0.64 Douglas-fir chronology • 38 series, 21 trees • Mean Sensitivity: 0.38 • Chronology Length: 1833-2007 • Inter-series correlation: 0.73 All EPS >0.85 Pinus ponderosa

  9. Results… Take it and like it! Relationship between tree ring index and precipitation (Summerland, BC) Pseudotsuga menziesii • Observations • Latewood is best correlated to precipitation (r = 0.57) • Dormant season precipitation was highly correlated with earlywood ring width (r = 0.39). • Summer precipitation was highly correlated with latewood ring width (r = 0.42)

  10. Results… Take it and like it! Relationship between tree ring index and precipitation (Summerland, BC) Pinus ponderosa

  11. Results… Take it and like it! Data Analysis Precipitation Correlation Values Psuedotsuga menziesii Precipitation Correlation Values Pinus ponderosa

  12. Results… Take it and like it! • Tree ring growth was not significantly related to large scale climatic anomalies (e.g. PDO, ENSO, AMO)

  13. Results… Take it and like it! Correlations between 500 hPa heights and tree ring index (Pseudotsuga menziesii)

  14. Results… Take it and like it!

  15. Results… Take it and like it! Correlations between sea surface temperature and tree ring index (Pseudotsuga menziesii)

  16. Discussion 1) Precipitation was the most limiting climatic factor in tree ring growth. 2) Latewood had a stronger response to precipitation than earlywood or total ring width measurement. 3) Tree ring index were correlated through time with May-July and previous Oct (PSME) and July only (PIPO). 4) No strong correlation with climate anomalies (e.g. ENSO, PDO). 5) SST and 500 hPa are correlated with tree ring index.

  17. Conclusions 1) Large tree ring networks provide stronger climate predictors. 2) Strong local climate signal demonstrate variability. 3) Earlywood, latewood, vs. ring width index. 4) Tree growth limited by more than ppt. 5) Large-scale circulation relationship, but not with ENSO, PDO.

  18. Thanks • Jim • Ze’ev • Henri • NSF & other funders • Hostel Steve, Gunbarrel, Apex Mtn

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