The influence of char on forest seedlings, soils and trees

Mark ColemanAssoc Professor & IFTNC Director

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Collaborators

Deborah Page-DumroeseRocky Mountain Research Station

Jim ArchuletaUmpqua NFCole MaynBitterroot NF

Margo WelchDeary District

• US FS R&D program on Woody Biomass• McIntire-Stennis• American Recovery and Reinvestment Act• AFRI Sustainable Bioenergy

Terry ShawMark KimseyKristin McElligottDan SmithShan ShanBhanu BhattaraiBrian Bell

Funding Bio-charCharKing

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

Background

Utilizing Forest BiomassProvides 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-char

Bio-oil

Syngas

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 charcoalpurports 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

Questions1. 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

OM (g g-1)

So

il m

ois

ture

(w

/w)

0.0 0.1 0.2 0.3 0.4 0.50.0

0.2

0.4

0.6AndisolMollisol

012

25

50% char (v/v)

OM (g g-1)

pH

0.0 0.1 0.2 0.3 0.4 0.56.0

6.5

7.0

7.5

8.0AndisolMollisol

Char & soil propertiesIncubation studies

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

Increased sorption and ion exchange capacity retains nutrients from leaching

…. in some soils

McElligott 2011

Char has long residence time in soilCarbon sequestration potential

• Stable aromatic ring structure• Decay resistant

• 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

Yea

r A

D

Yea

r A

D

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

Cellulase

OM (g g-1)

En

zym

e ac

tivi

ty

( m

ol h

-1 g

-1)

0.0 0.1 0.2 0.3 0.4 0.50

50

100

150

200

250AndisolMollisol

0

12

25

50

% char (v/v)

Chitinase

OM (g g-1)E

nzy

me

acti

vity

( m

ol h

-1 g

-1)

0.0 0.1 0.2 0.3 0.4 0.50

50

100

150AndisolMollisol

Phosphatase

OM (g g-1)

En

zym

e ac

tivi

ty

( m

ol h

-1 g

-1)

0.0 0.1 0.2 0.3 0.4 0.50

100

200

300AndisolMollisol

Peroxidase

OM (g g-1)

En

zym

e ac

tivi

ty

( m

ol h

-1 g

-1)

0.0 0.1 0.2 0.3 0.4 0.50

2

4

6

8AndisolMollisol

Soil Respiration

C (g g-1)

So

il R

esp

irat

ion

(m

ol m

-2 s

-1)

0.0 0.1 0.2 0.32.5

3.0

3.5

4.0

4.5

5.0AndisolMollisol

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 NField-collected soils

• Amino acid solution concentration increases along an elevation gradient

• Also related to the quality (N%) of the litter layer

0 500 1000 1500 20000

1

2

3

4AMECMERM

Elevation (m)

Am

ino

acid

-N (

mg/

kg)

Shan, Kimsey & Coleman unpublished

500 1000 1500 20000.0

0.5

1.0

1.5

2.0AMECMERM

Elevation(m)O

rgan

ic L

ayer

N (

%)

Char increases Organic N cyclingvaries with elevation of soil origin

Shan, & Coleman unpublished

Low Middle High0.0

0.5

1.0

1.5

2.0

2.5

Elevaton

Am

ino

acid

-N(m

g/k

g)

Low Middle High0

10

20

30

40

50

Elevaton

Am

ino

pep

tid

ase

acti

vity

(nm

ol/g

*h)

Low Middle High0.0

0.5

1.0

68

10

0%10%20%

Elevaton

AA

Tur

nove

r In

dex

(h-1

)

Char causes:• Decreased Amino-N pools• Increased amino acid production

(Amino peptidase activity)• Increased amino acid turnover

– five-fold in low elevation soil– 30% increase in high elevation soil

Field work confirms char increases AA productionindicates 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 Hypotheses1. 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

100%67%33%0%

aa a

a

Char:VP Mix

Char mixed in soilunfertilized

0% char 25% char 50% char0

1

2

3

4

5 a

bc

bb

c

ab

Abo

ve-g

roun

d B

iom

ass

(g)

0% sand 25% sand 50% sand0

1

2

3

4

5

CA

FA

a

abb b

cc

McElligott 2011

Need assurance that biochar application will not harm forest systems

• Tree growth may actually decrease depending on soil type• Similar response pattern with char and sand suggests the response is

not unique to char

Tree growth response

• Neutral to positive effects of char• Fertilizer enhances growth, but no added benefit with char• Slash effect rivals that of fertilizer• Short-term responses

Purdue Creek

Dia

met

er In

crem

ent

(in

/ y

r)

Control

Bioch

ar0.0

0.2

0.4

0.6

0.8

Swift Creek

Dia

me

ter

gro

wth

(in

2y

r-1)

Control

Char 1

.25

Char 1

0

Char 1

.25

+ Fer

tilize

r0.0

0.2

0.4

0.6

Purdue Creek

Dia

met

er In

crem

ent

(in

/ y

r)

Control

Bioch

arFer

t

Bioch

ar &

Fer

t0.0

0.2

0.4

0.6

0.8

Swift Creek

Dia

me

ter

gro

wth

(in

2y

r-1)

Control

Char 1

.25

Char 1

0

Fertil

izer

Char 1

.25

+ Fer

tilize

r

Char 1

0 +

Fertil

izer

0.0

0.2

0.4

0.6

Purdue Creek

Dia

met

er In

crem

ent

(in

/ y

r)

Control

Keep B

iom

ass

Bioch

arFer

t

Bioch

ar &

Fer

t0.0

0.2

0.4

0.6

0.8

Swift Creek

Dia

me

ter

gro

wth

(in

2y

r-1)

Control

Keep B

iom

ass

Char 1

.25

Char 1

0

Fertil

izer

Char 1

.25

+ Fer

tilize

r

Char 1

0 +

Fertil

izer

0.0

0.2

0.4

0.6

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

untreated fertilizer untreated fertilizer

biochar fertilizer & biochar biochar fertilizer & biochar

untreated fertilizer untreated fertilizer

biochar fertilizer & biochar biochar fertilizer & biochar

Thinned and No slash retention (0)

Thinned and All slash retained (1x) Thinned and Double Slash retained (2x)

Unthinned control

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