Above- and Below-ground Biomass and Soil
Organic Carbon Inventories of Willow Biomass
Crops Across a 19-year Chronosequence
Renato S. Pacaldo*, Timothy A. Volk, Lawrence P. Abrahamson, and
Russell D. Briggs
Department of Forest and Natural Resource Management, SUNY College of
Environmental Science and Forestry,
1 Forestry Drive, Syracuse, NY 13210
8TH BIENNIAL SRWC OPERATIONS WORKING GROUP CONFERENCE
SHORT ROTATION WOODY CROPS IN A RENEWABLE ENERGY FUTURE:
CHALLENGES AND OPPORTUNITIES
Overview
Introduction
Methods
 site selection and laylay-out of sampling plots
 belowground biomass
 aboveground biomass
 soil organic carbon
Results and Discussion
 biomass accumulation pattern across a 1919-yr chronosequence
on belowbelow- and aboveabove-ground biomass
 above
above-- and belowbelow-ground biomass ratio
 soil organic carbon
Conclusion
Introduction
Short Rotation Willow Biomass Crops:
Carbon Neutral (Keoleian
(Keoleian and Volk, 2005)
OR
Low Carbon Fuel?
Introduction
Previous Life Cycle Analysis (LCA) (Heller et al. 2003):
Willow biomass crops: low carbon fuel source
3.7 Mg CO2eqv ha-1 emissions over the 22 year lifespan
499 Mg CO2eqv ha-1 accumulated in above ground woody biomass
over 22 years
Introduction
Most studies focused on aboveground biomass
production
Limited data available on below ground biomass
Previous LCA estimate assumed belowground
biomass accumulation occurred over 3 rotations based
on harvested yield and shoot:root ratio of 1.75.
Why Important?
Belowground biomass is essential for determining
GHG balances and C allocation dynamics
Introduction
On soil organic carbon (SOC)
Ulzen-Appiah (2002) reported no measurable
changes in soil C in willow coppice systems
production for 12 years.
SOC in hybrid poplar declined at early stage
(Hansen, 1993) and then increased after 5
years (Grigal and Berguson, 1998; Coleman et.
al., 2004).
Same pattern across a 19-yr chronosequence?
Objectives
To inventory aboveabove- and belowbelow-ground biomass and soil
organic matter (SOM) across a 55-, 1212-, 1414-, and 1919- year
old willow (SV1 - Salix dasyclados
dasyclados)) chronosequence
chronosequence..
Variables measured
 Biomass:
 leaves, stems, and aboveground stool
 fine root, coarse root, and belowground stool
 total aboveground and total belowground
 Root
Root--shoot ratio
 SOM in 15 cm increments to 45 cm soil depth
H0: there is no significant difference in aboveabove- and
below-- ground biomass and soil organic carbon by age.
below
Study Sites
3 sites at Tully and 1 site at Lafayette, NY
Planted
1995
Planted
1997
Planted
1990
Planted
2004
Study Sites
6 plots/ site
Site characteristics
 Tully:
 Soil: gravelly silt loam, well-drained
 High Meadows, Lafayette Road
 Soil: gravelly silt loam, well-drained to somewhat
poorly drained

shallow bedrock and fragipan in some locations
 MAP ≈ 960 mm
 MAT ≈ 8 C
Species
Salix dasyclados (SV1)
5-year old willow crop
19-year old willow crop
During inventory period, the stems had been
growing for two years since the last cutting
Sampling Procedure
Taking samples for stem biomass
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Sampling Procedure
Leaf biomass, above- and below-ground stools biomasses
aboveground
stool
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belowground
stool
Cut the
stool
Take representative
plant within sampling
plot
Harvest leaves and stems
Sampling Procedure
Fine roots
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pit
Fine roots
Sampling depth: 45 cm in 15
cm interval
composite soil samples
for fine root biomass
hand pick the fine roots and
oven-dry at 65 C for 15 days
Sampling Procedure
Coarse roots (> 2 mm diameter)
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Sampling Procedure
Soil organic matter (SOM) in 15cm increments
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xsoil sample
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xSOMxdetermination
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x xon ignition
(LOI)
measure coarse
fragment volume
2 mm sieve
Statistical Analysis
ANOVA to find out significant difference of
biomass and SOC by age classes
if the results are significantly different,
treatment means are compared by Least
Significant Difference (LSD) test.
univariate procedure – for testing normal data
distribution
Leven’s test – for testing homogeneity of
variance
Results and Discussion
Salix dasyclados belowground biomass
16.0
14.0
12.0
Mg ha-1
10.0
Belowground Stool
8.0
Coarse Roots
Fine Roots
6.0
4.0
2.0
0.0
5-yr old
12-yr old
14-yr old
19-yr old
Salix dasyclados stem & leaf biomass
(annual yield)
25
leaf biomass
stem biomass
20
Mg ha-1 yr-1
17.6
15
10
5
7.2
3.3
2.6
0
5-yr old
12-yr old
14-yr old
19-yr old
Salix dasyclados aboveground stool
biomass (total yield)
14.0
12.0
10.2
Mg ha-1
10.0
8.0
6.0
4.8
4.0
2.0
0.0
5-yr old
12-yr old
14-yr old
19-yr old
Salix dasyclados above- and below- ground
biomass (total yield at time of inventory)
60
48 Mg ha-1
50
aboveground
biomass
Mg ha-1
40
30
22 Mg ha-1
21 Mg ha-1
20
10
belowground
biomass
13 Mg ha-1
0
5-yr old
12-yr old
14-yr old
19-yr old
Below- and above- ground biomass ratio
(kg/plant)
(kg/plant)
Below:Aboveground Ratio
(R:S Ratio)
19
2.33a (0.37)
4.24a (0.24)
1:1.82
14
2.39a (0.10)
4.39a (0.49)
1:1.83
12
2.88a (0.28)
2.93b (1.06)
1:1.02
5
1.48b (0.11)
2.16 b (0.46)
1:1.46
P values
n=24
<0.0001
<0.0001
Age (yr)
Total Belowground Total Aboveground
Biomass
Biomass
Consistent with other studies on SR ratio:
1.75 (Heller et al 2003)
1.40 (Volk, 2002) – for young Salix
dasyclados (SV1) clone
The higher SR ratio (i.e 1.8) in Tully compared to Lafayette
site (1.0) could be attributed to the differences in site quality
Tully Study Sites (Age 5, 14, 19)
Lafayette Study Site
(Age: 12)
Age
Bulk density in
30-45 cm depth
(g/cm3)
5
1.3 -1.6
12
1.5 - 1.7
14
1.3 - 1.4
19
1.0 - 1.2
In poor site, about
60% of NPP is used
to develop short-live
roots (Reyes et al.,
1981)
Salix dasyclados Soil Organic Carbon (SOC)
200
182 Mg ha-1
Mg ha-1
180
175 Mg ha-1
160
140
120
100
0-yr old
5-yr old
12-yr old
14-yr old
19-yr old
Salix dasyclados Soil Organic Carbon (SOC) by Depth
120
SOC (Mg ha-1)
100
0-15 cm
15-30 cm
30-45 cm
80
60
40
20
0
5-yr old
14-yr old
19-yr old
Age
12-yr old
SOC in this study is consistent with some
previous reports:
No detectable changes in microbial biomass
carbon (labile carbon) in SRWC across a 12-yr
chronosequence (Ulzen-Appiah, 2002)
SOC declined at early stage (Hansen, 1993)
and then increased after 5 years (Grigal and
Berguson, 1998; Coleman et. al., 2004).
SOC in SRWC poplar ranged from 20 to more
than 160 Mg ha-1 (Coleman et al., 2004).
Estimates of GHGs gas flows per hectare of willow plantation,
accumulated over 7 rotations
LCA Results from Heller et al. (2003)
Current Study
CO2
(Mg CO2 eq
ha-1)
CO2
(Mg CO2
ha-1)
Other GHG Total
(Mg CO2
(Mg CO2
eq ha-1)
eq ha-1)
Diesel fuel
3.1
0.1
3.2
3.2
Agr Inputs
2.9
0.4
3.4
3.4
N2O from N fertilizer
3.9
3.9
3.9
N2O from foliage
7.3
7.2
7.2
Emissions
C Sequestration
Below ground
-14.1
-14.1
Soil C
0
0
Net Total
-8.0
Harvested Biomass
-499.2
11.7
3.7
-499.2
-38.5
0
-20.8
Conclusions
There is significant difference in total belowground biomass
across a 1919-year chronosequence
increases until about age 12, and stabilize onward with slight
variations.
No significant difference in belowground stool biomass between
ages 55- and 1212- year old and between ages 1414- and 1919-year old
SRWC plantation.
Aboveground biomass is significantly different across the
chronosequence and increases with age.
No significant difference in SOC across a19a19-year
chronosequence .
Limitation of this study: site quality confounded the effects of
age as shown in Lafayette site. Variation of site quality is one of
the major sources of error in chronosequence studies (Yanai
(Yanai et
al., 2000).
Acknowledgment
This study was carried out with the funding support
from USDA Rural Development through Timothy A.
Volk and Lawrence P. Abrahamson.
We wish to thank the following people for their help during the
data collection
Project Staff:
Rebecca Allmond, Eric Fabio, Philip Castellano, and Ken Burns
Student Assistants:
Jacob Bakowski, Tyler Harvey, Gabe Kellman, Jason Maurer,
Ryan Newby, and Devin Mc Bride
Thank
You!