CARBON SEQUESTRATION BY CARBON SEQUESTRATION BY HYBRID POPLARS IN THE PACIFIC HYBRID POPLARS IN THE PACIFIC NORTHWESTNORTHWEST

Dr. Jon D. JohnsonDr. Jon D. Johnson

Hybrid Poplar Research ProgramHybrid Poplar Research Program

Washington State University - Puyallup Washington State University - Puyallup

Research & Extension Center, Research & Extension Center, Puyallup, WashingtonPuyallup, Washington

poplar@wsu.edupoplar@wsu.edu

www.puyallup.wsu.edu/poplarwww.puyallup.wsu.edu/poplar

Overview• Funded by DOE SBIR through Broadacres

Nursery, Hubbard, OR

• Objectives1. Determine above- and below-ground carbon

sequestration rates for commercial hybrids during an 8 year plantation cycle.

2. Quantify changes in soil carbon as related to plantation development and vegetation.

3. With carbon sequestration, biomass and morphometric data from 1. develop and validate a field method for estimating carbon sequestration rates for hybrid poplar.

Why Hybrid Poplar?

• Fast growingFast growing

• Straight stemsStraight stems

• Dioecious (male and female Dioecious (male and female trees)trees)

• Easily propagatedEasily propagated

18 month old tree in Central Valley of California

Methods

• 3 clones growing in eastern Oregon: 184-411, 52-225, OP-367

• 4 ages: 2, 4, (5), 6 and 8 years old •2 clones growing in western Oregon: 184-411, 52-225

• 3 ages: 5, 6, and years old • 5 trees per clone-age class• Above ground biomass & carbon• Below ground biomass & carbon• Soil carbon at 0-30 and 30-100 cm

•Fractionated soil C

Site Locations

++

Dallas

Hermiston

West East

Silty clay loam

Sand

Above-ground SamplingAbove-ground Sampling

Standing trees were measured for height and Standing trees were measured for height and diameter; After felling, stems and branches were diameter; After felling, stems and branches were processed by whorlprocessed by whorl

All tree parts were weighed in the field andAll tree parts were weighed in the field andsubsamples taken for dry weight conversionsubsamples taken for dry weight conversionand carbon contentand carbon content

Stumps were excavated and then roots Stumps were excavated and then roots were separated from stump;were separated from stump;each weighed separately and each weighed separately and subsamples were taken for dry weight subsamples were taken for dry weight conversion and carbon contentconversion and carbon content

Below-ground SamplingBelow-ground Sampling

Tree Carbon Distribution

0

20

40

60

80

100

120

Co

mp

on

en

t T

ota

l Car

bo

n (

Kg

)

2 4 8 2 4 5 8 2 4 6 8

52-225 52-225 52-225 184-411 184-411 184-411 184-411 OP-367 OP-367 OP-367 OP-367

Clone and Age

Branches

Stem

Stump

Roots

6.4

28.1

95.4

7.4

24.333.9

77.9

6.4

24

53.3

103.7

Carbon Sequestration Rates

y = 2.9934e0.4609x

R2 = 0.9769

y = 3.4911e0.4289x

R2 = 0.9412

y = 4.2945e0.381x

R2 = 0.9509 y = 1.2221e0.4957x

R2 = 0.9469

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6 7 8 9

tree age

Tota

l Tre

e C

arbo

n (K

g)

52-225

184-411

OP -367

15-29W

52-225W

Expon. (OP -367)

Expon. (52-225)

Expon. (184-411)

Expon. (15-29W)

Total C

Summary – Mean Annual Sequestration Rate Total C

(Mg/ha/y)

Total tree C

(Kg/y)

11.2

11.5

20.0

14.9

18.3

7.3

7.5

13.0

9.7

11.9

89.6

92.0

160.0

119.2

146.4

Total C @ 8 y

(Mg/ha)

52-225 W

15-29 W

OP-367 E

184-411 E

52-225 E

Clone/Location

•6 samples/tree (pooled); 6 samples/tree (pooled); 5 trees /clone5 trees /clone

•2 depths: 0-30 and 30-100 cm2 depths: 0-30 and 30-100 cm

•Adjacent fields sampled: Adjacent fields sampled: crop and native vegetation (E)crop and native vegetation (E)

•Fine roots removed, dried Fine roots removed, dried andand weighedweighed

•Boiling water extraction to Boiling water extraction to estimate labile soil C (E)estimate labile soil C (E)

Soil SamplingSoil Sampling

Soil Carbon

Clone-site C% 0-30 cm C% 30-100 cm52-225 E 0.41 0.22

184-411 E 0.41 0.3

OP-367 E 0.35 0.25

crop E 0.33 0.12

native E 0.29 0.14

Mg ha-14.29

5.16

4.34

2.84

2.87

52-225 W 2.5 0.8

15-29 W 2.44 0.9

grass W 2.04 0.87

14.41

14.98

13.43

7.3

11.5

% increase over crop51.4

82.0

53.0

Labile Soil Carbon (E)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

La

bile

C/T

ota

l C

184-41152-225OP-367CropNative

R2

= 0.9763

R2

= 0.9768

Volume

Tre

e C

arb

on

Predicting Tree Carbon

Total C

Aboveground C

ConclusionsConclusions

• Hybrid poplars are capable of sequestering high Hybrid poplars are capable of sequestering high amounts of Camounts of C

• Soil C increased significantly in hybrid poplar Soil C increased significantly in hybrid poplar plantations when compared to adjacent crop plantations when compared to adjacent crop land (7-82% depending on soil texture)land (7-82% depending on soil texture)

• Over time, the proportion of labile soil C Over time, the proportion of labile soil C decreaseddecreased

• Standing tree C can be predicted with easy to Standing tree C can be predicted with easy to measure parameters allowing for third party measure parameters allowing for third party verification of C storage verification of C storage