The influence of char on forest seedlings, soils and trees
Mark Coleman
Ladd Livingston, Idaho Department of Lands, Bugwood.org
Assoc Professor & IFTNC Director
Collaborators
Deborah Page-Dumroese
Rocky Mountain Research
Station
Jim Archuleta
Umpqua NF
Cole Mayn
Bitterroot NF
Terry Shaw
Mark Kimsey
Kristin McElligott
Dan Smith
Shan Shan
Bhanu Bhattarai
Brian Bell
Margo Welch
Deary District
Funding
•
•
•
•
US FS R&D program on Woody Biomass
McIntire-Stennis
American Recovery and Reinvestment Act
AFRI Sustainable Bioenergy
Bio-char
CharKing
B
a
c
k
g
r
o
u
n
d
High interest in thinning small diameter stands
•
•
•
•
Private investment returns
Public lands are over stocked
Protection: wildfire, pests infestation, drought
Policy: Healthy Forests Initiative, National Fire Plan, etc., Energy
Independence and Security Act
• Adaptation to Climate Change
• Cost prohibitive
Utilizing Forest Biomass
Provides management opportunities
• Interest in utilizing woody
biomass for energy
• What are the ecological
consequences of forest
biomass removal?
• Can any negative impacts
be mitigated?
Fast Pyrolysis
Small scale units
• In woods processing
• Avoid biomass transport costs
• High value oil product
• Research required
• Funding scarce
Bio-oil
Syngas
Bio-char
Biochar is equivalent to native charcoal in forest
ecosystems
• Char is common in fire-adapted
ecosystems
• Fire suppression decreases charcoal
inputs
• Biomass removal decreases the likelihood
of fire occurring
• Applying char as a co-product of pyrolysis
removes wildfire hazard and retains soil
ecosystem function
Site amendment with charcoal
purports to:
• Return nutrients back tot the site of biomass removal
• Improve soil characteristics
• Enhance site quality
Objective
• Evaluate impacts of biomass removal and char
amendments on forest soil productivity
Questions
1. What soil properties are affected by char?
2. Do char amendments alter tree growth; if so in
which direction?
Char porosity alters physical soil properties
• Porosity
– 80% void space
• Increased surface area
– 200-400 m2 / g
• Decreased bulk density
– Char BD is 0.2 – 0.4 g/cc
– Soil BD ranges from 1.0
to 1.7 g/cc
Char & soil properties
Incubation studies
(v /v
har
c
%
25
8 .0
)
A n d is o l
50
A n d is o l
M o llis o l
M o llis o l
7 .5
12
0 .4
0
pH
S o il m o is t u r e ( w /w )
0 .6
7 .0
0 .2
6 .5
0 .0
0 .0
6 .0
0 .1
0 .2
0 .3
O M (g g
-1
0 .4
0 .5
)
Char responses to char are consistent,
but often depend on soil type
• Increased organic matter
• Increased water holding capacity
• Increased pH
Coleman, Shan & Smith unpublished
0 .0
0 .1
0 .2
0 .3
O M (g g
-1
)
0 .4
0 .5
Increased sorption and ion exchange capacity
retains nutrients from leaching
…. in some soils
McElligott 2011
Char has long residence time in soil
• But, char may speed decomposition of
native soil organic matter
• Char enhances microbial activity
• Sequestration may not equal the amount
applied if active microbes consume more
Year AD
• Stable aromatic ring structure
• Decay resistant
Year AD
Carbon sequestration potential
Whitlock & Larsen. 2001
Charcoal is used to
date ancient fires
Does char speed the loss of soil organic matter ?
Wardle et al 2008
• Litter bags containing:
• humus
• char
• humus + char
• Mixing humus with
char causes greater
mass loss than
expected
Does char increases organic matter decomposition?
• Activity of decomposition enzymes decreases with greater char
• No effect found on soil respiration
• Conclude OM consumption does not increase with char
C h i t in a s e
C e l lu la s e
150
A n d is o l
150
50
100
50
)
M o llis o l
-1
/v )
g
(v
25
M o llis o l
100
-1
ar
( m o l h
-1
ch
A n d is o l
E n z y m e a c tiv ity
12
200
g
-1
)
%
( m o l h
E n z y m e a c tiv ity
250
0
50
0
0
0 .0
0 .1
0 .2
0 .3
-1
O M (g g
0 .4
0 .0
0 .5
0 .1
)
0 .2
0 .3
O M (g g
P h o s p h a ta s e
-1
0 .4
0 .5
)
d ir
as
S oPile rRoexsi p
ae
t io n
300
58.0
( m o l h
100
0
0 .0
0 .1
0 .2
0 .3
O M (g g
-1
)
0 .4
0 .5
-1
4 .5
6
-2
-1
-1
(m
mo
h gs ))
o ll m
(
200
A
A nn d is o l
n
tioity
S
c tiv
z yRmees paira
n il
Eo
g
-1
)
M o llis o l
-1
E n z y m e a c tiv ity
A n d is o l
4 .0
M
M oo llis o l
4
3 .5
2
3 .0
20.5
0 0.0.0
0 .1
0 .10 .2
0 .3 0 .2
0 .4
.3
00.5
-1
-1
OC
M ((gg gg ))
Coleman, Shan & Smith unpublished
Does char alter organic nitrogen cycling?
• Importance of organic N in
forests now accepted
• Litter organic matter, N
mineralization are correlated
with productivity
• Amino acids are acquired by
roots
• Amino acid pools and fluxes
are is easily measured
{Nasholm, 2009 #5834}
Soluble organic N
Field-collected soils
2 .0
AM
ECM
O r g a n ic L a y e r N ( % )
A m i n o a c id - N ( m g /k g )
4
ERM
3
2
1
0
AM
ECM
1 .5
ERM
1 .0
0 .5
0 .0
0
500
1000
E le v a t i o n ( m )
1500
2000
500
1000
1500
2000
E le v a tio n (m )
• Amino acid solution concentration increases along an
elevation gradient
• Also related to the quality (N%) of the litter layer
Shan, Kimsey & Coleman unpublished
Char increases Organic N cycling
varies with elevation of soil origin
1 .0
0 .5
0 .0
M id d le
H ig h
E le v a to n
L ow
M id d le
H ig h
E le v a to n
Char causes:
• Decreased Amino-N pools
• Increased amino acid production
(Amino peptidase activity)
• Increased amino acid turnover
50
40
(n m o l/g * h )
0 .5
0 .0
L ow
A m in o p e p t id a s e a c t i v i t y
1 .0
)
1 .5
20%
10%
0%
-1
(m g /k g )
A m in o a c id - N
2 .0
10
8
6
(h
A A T u rn o v e r In d ex
2 .5
30
20
10
0
L ow
M id d le
E le v a to n
Shan, & Coleman unpublished
H ig h
– five-fold in low elevation soil
– 30% increase in high elevation soil
Field work confirms char increases AA production
indicates greater N cycling
• Amino Acid production
– Char rates are twice the control in early
season
– equal in late season
Smith 2013
Potential forestry applications
Does amino acid turnover indicate differences in
site quality?
Testable Hypotheses
1. Site quality is directly correlated with amino acid
production rate.
2. Forest productivity correlates with soil organic
matter and organic N cycling rates.
3. Assays of amino acid production in forests are
analogous to N mineralization measurement in
agronomic soils.
4. Amino acid production rate is consistently high
during wet season.
How does char affect tree growth?
Poplar grown with various proportions
of char and vermiculite-peat potting
mix; fertilized
• There is no growth stimulation
a
a
a
a
Char:VP Mix
0%
33%
67%
100%
Char mixed in soil
unfertilized
Above-ground Biomass (g)
• Tree growth may actually decrease depending on soil type
• Similar response pattern with char and sand suggests the response is
not unique to char
5
4
a
5
a
ab
4
b
b
ab
b
b
FA
bc
3
CA
c
3
c
c
2
2
1
1
0
0
0% char
25% char
50% char
0% sand
25% sand
50% sand
Need assurance that biochar application will not harm forest
systems
McElligott 2011
Tree growth response
P u rd u e C re e k
S w ift C re e k
-1
D ia m e t e r g r o w t h ( in 2 y r )
0 .6
( in / y r )
D ia m e t e r In c r e m e n t
0 .8
0 .4
0 .2
0 .2
0 .0
e
e
F
F
&
r
a
o
tr
h
C
n
B
io
c
p
e
e
K
•
•
•
•
0 .4
rt
rt
r
a
h
c
io
B
B
C
io
o
m
n
a
tr
s
o
s
l
0 .0
0 .6
K
e
e
o
p
l
B
io
m
a
s
s
C
h
a
r
1
.2
5
C
h
a
r
1
0
F
C
h
a
r
e
r
1
l
ti
.2
iz
5
e
+
C
r
F
h
e
a
rt
r
i
il
1
ze
0
+
r
F
e
r
l
ti
iz
e
r
Neutral to positive effects of char
Fertilizer enhances growth, but no added benefit with char
Slash effect rivals that of fertilizer
Short-term responses
Coleman, Page-Dumroese et al unpublished
Using PCT stands to evaluate biomass removal impacts
• Established trees have exploited site
• Seedlings need to become established, delayed inter-tree
competition
• Young trees are responsive to treatment
Sustainable Bioenergy
Unthinned control
untreated
fertilizer
biochar
fertilizer & biochar biochar
Thinned and All slash retained (1x)
untreated
fertilizer
biochar
Thinned and No slash retention (0)
untreated
fertilizer
fertilizer & biochar
Thinned and Double Slash retained (2x)
untreated
fertilizer
fertilizer & biochar biochar
fertilizer & biochar
Utilizing Forest Biomass
Conclusions
• Numerous motivations to develop forest bioenergy
• Portable units appealing, but require development
• Char is a novel forest product
– Used to sequester carbon and enhance soil quality
• Incubation studies demonstrate soil properties:
– Water holding capacity, pH, nutrient retention, exchange capacity, etc
• Char doesn’t increases organic matter decomposition
• New tools to measure organic N cycling indicates increases
char; applications to forest nutrient management
• Monitoring PCT responses is sensitive measure of biomass
removal and soil amendments
Bitterroot Bandits 2010