Predicting current and future tree diversity in the Pacific

Northwest

Predicting current and future tree diversity in the Pacific

Northwest

I R S S

Richard Waring1

& Nicholas Coops2

1 Oregon State University 2 University of British Columbia

Richard Waring1

& Nicholas Coops2

1 Oregon State University 2 University of British Columbia

Process-based Model of GPP & NPP

Environmental Modifiers

VPD

Soil Water

Tmin

Frost

Quantum / Radiation Use Efficiency

x

PAR

x PAR

Rainfall

GPP & NPP

Additional 3-PGS Modifiers

Environmental constraints on photosynthesis for

Douglas-fir in the Pacific NW, U.S.A.

soil water

evaporative demand suboptimal

temperature

Frost limitations

Current environmental constraints on photosynthesis for Douglas-fir in British Columbia, Canada

Soil drought Evaporative demand (D)

Suboptimal temperature

Frost frequency

Species differences in sensitivity to environment

soil drought evaporative demand

Suboptimal temperature frost sensitivity

Different adaptations sort environmental distributions of NW tree species

Common name scientific name environmental adaptations

Sitka spruce Picea sitchensis (Bong.) Carr most sensitive to humidity deficits & temperature extremes

ponderosa pine Pinus ponderosa Dougl. ex Loud. more adapted to drought, frost, and humidity deficits than Douglas-fir

western juniper Juniperus occidentalis Hook. most adapted to drought and high VPD

lodgepole pine Pinus cortorta Dougl. ex Loud. most tolerance of frost

Douglas -fir Pseudotsuga menziesii (Mirb.) Franco

adapted to intermediate environmental conditions

western hemlock Tsuga heterorphylla (Raf.) Sarg. more sensitive to humidity deficits and to drought than Douglas-fir

Defining different species environmental

tolerances in reference to Douglas-fir

Sitka sprucelodgepole pine

Ponderosa pine

Frosttolerant

Droughttolerant

Drought adverse

3737 USDA Forest Service Forest Inventory & Analysis Plots

Current range predictions (left) vs. FIA plots data(right)

of western hemlock(upper) and Sitka spruce (lower)

Current Range Predictions (left) and FIA plot locations (right) for ponderosa pine (upper) and

lodgepole pine (lower)

Reported range of lodgepole pine in B.C.

Little’s range map

Present on field plots

Model predicts progressive reduction in range of lodgepole pine with environment

favoring other species in BC

2020 2050 2080

Summary

• Process-based models weight environment limitations as they affect photosynthesis and growth

• Approach simplified by relating to most widely distributed species

• Decision trees analysis automatically defines environmental thresholds for different species

• Predictions of present range good, and potential to predict future ranges, taking into account competition with other species.