Comparison of water fluxfrom Douglas-fir and Oregon

white oak of varying age and stature

Nathan Phillips, Barbara BondNate McDowell, Andrew Schauer,

Mike Ryan, Eric Watrud, Nate Gehres,

Temperate conifer Dry angiosperm Tropical angiosperm

Landsat TM, Wind River Canopy Crane Research Facility

Betts et al. 1997, Nature

Field et al. 1999

Yoder et al. 1994

XX

X

Mountain Ash Forest, AustraliaA

nn

ual

Wat

er F

lux

(cm

)

0

30

60

90

120

0 50 100 150 2000

30

60

90

120

Forest Age (y)

Stream flow

Evapo-transpiration

Watson et al. 1999

Objectives•Determine whether tall trees show reduced transpiration compared to smaller trees

•Scale whole-tree water use estimates to the ecosystem and compare age classes

•Compare transpiration estimates to ecosystem latent heat fluxes estimated using eddy covariance (Doug-fir only) [thanks KT Paw U, Jiquan Chen, Mattias Falk, Tom King]

Suite of tests:

Parameter Predicted change w/ size

sap flow decrease

stomatal conductance decrease

latent heat flux decrease (?)

Methods

•sap flux measurements: constant thermal dissipation technique (Granier-Type).

•Sampling: 6-9 trees in 20, 40, and 500 y old doug-fir stands; 8 trees each in old/young oak

•Sub-sampling: 2-5 points within trees •Study period: 1998,99 summer months for Doug-fir; 1999 summer for oak

•eddy covariance: 20 and 500 y old Doug-fir stands

Douglas-fir Study Area

Southern Washington

•Douglas fir dominated•3 age class sites within 10 km •2.5 m annual precipitation•9 oC mean annual temperature•350 - 500 m elevation

500 y, 65 m tall 40 y, 35 m tall 20 y, 15 m tall

Wind River, WA

180 210 240 270

Vo

l. s

oil

mo

istu

re (

m3 m

-3)

0.25

0.30

0.35

0.40

0.45

Day of year

0.25

0.30

0.35

0.40

0.45 20 y40 y500 y

1998

1999

Wind River, WA

180 210 240 270

0

1

2

3

420 y40 y500 y

Tra

ns

pir

ati

on

(m

m d

-1)

0

1

2

3

4

1998

1999

Wind River, WA 1998-1999

500 y transpiration (mm d-1)0 1 2 3 4

20

y t

ran

sp

ira

tio

n

(

mm

d-1

)

0

1

2

3

4Y = 0.3 + 2.1Xr2 = 0.61

Sa

pfl

ow

(mm

h-1

)

0.0

0.1

0.2

0.3 20 y500 y

VP

D (

kP

a)

0

1

2

3

4

P

AR

(mm

ol

m-2

s-1

)

0.0

0.5

1.0

1.5

2.0 PAR20 y VPD500 y VPD

August 2 (moist soil) Sept. 14 (dry soil)

Time (h)6 12 18 24 6 12 18 24

Wind River, WA 1998

Phillips et al., AGU 1999

Wind River, WA July 27-29, 1999

0.0

0.2

0.4

0.620 y40 y500 y

(mm

h-1

)

0.0

0.2

0.4

0 12 24 36 48 60 720.0

0.2

0.420 y500 y

Eddy covariance ecosystem flux

Sapflow per ground area

Sapflow per leaf area

(mm

ol

m-2

s-1

)

Time (h)

Wind River, WA July 27-29, 1999

0.0 0.1 0.2 0.3 0.4 0.5

20

y E

dd

y C

ov

. (m

m h

-1)

0.0

0.1

0.2

0.3

0.4

0.5Y= 0.01 + 0.65Xr2 = 0.86

500 y sapflow (mm h-1) 500 y Eddy Cov. (mm h-1)0.0 0.1 0.2 0.3 0.4

20

y S

apfl

ow

(m

m h

-1)

0.0

0.1

0.2

0.3

0.4

0.5Y= -0.02 + 3.4Xr2 = 0.96

Wind River, WA 1999

Aug 2 Sept 14(moist soil) (dry soil)

GC

,D (

mm

s-1

)

0

2

420 y500 y

Oregon white oak

-600

-400

-200

0

TD

R n

3.5

4.0

4.5YoungOLD

A,B: Corvallis met data - Hyslop Experimental Station, Oregon Climate Service

Day of year (May 1, 1999 - Oct 15, 1999)

Rai

n, E

vap

ora

tio

n (

mm

)

02468

1012

Cumulative Evaporation - Rain

Rain EvaporationA.

B.TDR

Quercus garryana 1999, Corvallis OR

LA

I (m

2 m-2

)0

1

2

3

4p = 0.48 n = 25 traps n = 14 traps

25 m 10 m

LA

/SW

A (

m2 c

m-2

)

0.0

0.1

0.2

0.3

0.4p < 0.00001 (assuming no error in SWA)

SW

A (

m2 h

a-1)

0

5

10

Sa

p F

lux

(g

m-2

s-1

)

0

10

20

30

40

50

0

10

20

30

40

E (

mm

h-1

)

0.00

0.03

0.06

0.09

0.12

OldYoung

May 22 - 28 June 19-23 Sept 28 - Oct 4

Time (d)

Quercus garryana Corvallis, OR , 1999

Quercus garryana Corvallis, ORMay 22 - Oct 4, 1998

Young E (mm h-1)

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

Old

E (

mm

h-1

)

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

Old = 0.001 + 0.40 Youngr2 = 0.95

Quercus garryana Corvallis, OR 1999

25 m 10 m

Tra

nsp

irat

ion

(m

m d

-1)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Future Directions

3PG Model Structure

Bogh et al. 1999 Remote Sens. Environ.

2 cm

Phillips et al. (NSF in review) adapted from Liu 1985

Nate M.

Nate G.

Heather M, Megan V.H.

Hyun K.

Eric W.

Acknowledgements

Andy S.

Seth M.