Predicting Current and Future Tree Diversity in the Pacific Northwest I R S S Richard Waring 1 Nicholas Coops 2 1 Oregon State University 2 University of British Columbia Richard Waring 1 Nicholas Coops 2 1 Oregon State University 2 University of British Columbia

Pinyon pine in New Mexico stressed by multi-year drought & killed by bark beetles

Drought-induced mortality in southern California except along ephemeral streams

Lodgepole pine killed by mt. pine beetle in British Columbia not related to drought

Extensive bark beetle outbreaks over the last few decades Raffa et al. 2008, BioSci. 58:

Questions: I. Has climatic variation increased tree mortality? II. If so, where do we expect changes in a species’ distribution and why?

Approach: Compare recent changes in temperature and precipitation patterns Translate climatic variables as they affect tree growth Determine where conditions cause stress on different species Predict future (potential) distributions of major tree species

Pacific Decadal Oscillation Pacific Decadal Oscillations warm and cool phases calibration assessment SEA TEMPERATURE AFFECTS LAND CLIMATE

Winter Precip. Spring Precip. Summer Precip. Fall Precip. Seasonal Changes in Precipitation ( )- ( )

Winter Temp. Spring Temp. Summer Temp. Fall Temp. Seasonal Changes in Temperature ( )- ( )

Use a physiologically- based model to define how seasonal variations in climate affect Douglas-fir NPP A Soil Water GPP Stomatal Conductance VPD Temp NPP B Canopy Quantum Efficiency Light absorbed canopy (APAR) Canopy Interception Growth Partitioning Precipitatio n Solar Radiation (50% PAR) Transpiration Soil Fertility LAI

Predicted Mean Leaf Area Index (Range: 1 to 9) Predicted Mean Leaf Area Index (Range: 1 to 9)

Predicted Change in Leaf Area Index ( )-( ) (Range:  3.0)

Comparison of predicted changes in Leaf Area Index for Level 1 Ecoregion

Relative change in environmental constraints on Douglas-fir growth (1976 to 2006) – ( ) Spring Frost Fall Soil H 2 0Winter Temperature More optimum conditions Less optimum conditions

Principal Drivers for change in LAI (1976 to 2006) – ( )

Tree species differ in their abilities to compete, based on seasonal variation in frost (FRT), available soil water (SW), humidity deficits (vpd), and temperature Size of slice = rel. importance

Decision tree analysis After Coops & Waring Climatic Change (in press)

Distribution of Douglas-fir General map (Little) Recorded field records (red) Predicted range with Decision Tree Model & Mean climate %  3% accuracy

Predicted stressed (red) and improved areas (green) since period Douglas-fir lodgepole pine ponderosa pine

Predicted lodgepole pine distributions Current Coops, N.C. & R.H. Waring Climatic Change (in press)

Conclusions We are in a period where sea temperatures are as warm as they have been in the last 100 years, and likely to increase. Where our model predicts a reduction in leaf area index for Douglas- fir, an increase in tree mortality can be expected with more drought- prone species favored (e.g.,ponderosa pine). Where an increase in leaf area index for Douglas-fir is predicted, lodgepole pine and other subalpine species are likely to be replaced in time. Trends are predicted to continue, and to accelerate

Additional Information R.H. Waring N.C. Coops Project