Acidification constraints on carbon and nitrogen (mainly soil) dynamics Filip Oulehle, Chris Evans,...

Acidification constraints on carbon and nitrogen (mainly soil)

dynamics

Filip Oulehle, Chris Evans, Henning Meesenburg, Jakub Hruška, Pavel Krám, Oldřich Myška, Jiří Kopáček, Jack Cosby, Dick Wright

Six things that I am going to talk about:

• Global extent of acid deposition (S and N)

• Effects of acid deposition on forest soil carbon accumulation

• Effects of acid deposition on DOC leaching from soils

• Linkages between DOC availability and soil respiration

• Effects of acid deposition on forest productivity

• Coupled C and N dynamics in MAGIC model

Total S deposition (mg m-2 yr-1)

2000

Total N deposition (mg m-2 yr-1)

2000

Dentener F. et al., 2006, GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 20, GB4003

Ratio of total N deposition for scenario CLE (2030) compared to base simulation (2000)

Simulation of future (2030) S deposition using CLE (Current Legislation scenario)

Smith S.J. et al., 2011, ATMOSPHERIC CHEMISTRY AND PHYSICS, 11, 1101–1116

Global extent of sulphur and nitrogen deposition

Soil Carbon Cycle

Plants

Soil Organic Matter (SOM)

Decomposer Turnover

CO2

litter C respiration

Dissolved Organic Material (DOM)

DOC DON

12

3

4

5

Effects of acid deposition on soil C accumulation

Experimental evidence:

- Suppression of litter decomposition under simulated acid (S) deposition (e.g. Pennanen et al., 1998; Persson et al., 1989)

- Adverse effect of aluminium on C availability for microorganisms (e.g. Scheel et al., 2007)

- pH effect on microbial enzyme activity (e.g. Sinsabaugh, 2010)

Al addition (as AlCl3):

effects on soil water chemistry

Al addition:

effects on soil respiration

C

A2

0

50

100

150

200

250

um

ol l

-1

Control A0 A1 A2

Treatment

Aluminium

3

3.2

3.4

3.6

3.8

4

4.2

4.4

um

ol l

-1

Control A0 A1 A2

Treatment

pH

3

8

13

18

23

28

33

um

ol l

-1

Control A0 A1 A2

Treatment

DOC

Mulder J. et al., 2001, WATER, AIR AND SOIL POLLUTION 130: 989-994

Long-term evidence:- Across Czech forest catchments (n=14), S bulk deposition explained 32% variability in soil C/N ratio and 50% variability in forest floor depth (Oulehle et al., 2008)

Nacetin spruce forest research plot:

Source www.emep.int

Wet deposition of sulphur (top) and nitrogen (bottom) in Europe based on the EMEP model


0

10

20

30

40

50

60S throughfallN bulk

S an

d N

dep

ositi

on (k

g ha

-1 y

r-1)

1994 1997 2003 20100

5

10

15

20

5.80 5.33 4.18 3.74

Forest floor massForest floor C pool

Fo

rest

flo

or

OM

po

ol

(kg

m-2

)

Oulehle F, Evans C.D., Hofmeister J et al., 2011, GLOBAL CHANGE BIOLOGY 17, 3115-3129

0

10

20

30

40

50

60

f(x) = − 2.60127411635608 x + 48.8546156167492R² = 0.887078505318422

S throughfallLinear (S throughfall)N bulk

S an

d N

dep

ositi

on (k

g ha

-1 y

r-1)

1994 1997 2003 20100

5

10

15

20

5.80 5.33 4.18 3.74

Forest floor massForest floor C pool

Fo

rest

flo

or

OM

po

ol

(kg

m-2

)

y=-0.133x + 269.83R2=0.95

Nacetin spruce forest research plot:

- Forest floor C pool reduced by 47% since 1994

- Total S deposition reduced by 77% since 1994

dC/dS = 509

Oulehle F, Evans C.D., Hofmeister J et al., 2011, GLOBAL CHANGE BIOLOGY 17, 3115-3129


Solling (Germany) spruce forest research plot:

Source www.emep.int

Wet deposition of sulphur (top) and nitrogen (bottom) in Europe based on the EMEP model

0

20

40

60

80

100


S an

d N

dep

ositi

on (k

g ha

-1 y

r-1)

1968 1973 1979 1983 1987 1990 1991 1995 2001 20100

5

10

15

2.45 2.82 3.434.87 5.09 6.13 5.56 5.30 5.19

3.75

Forest floor mass

Forest floor C poolF

ore

st f

loo

r O

M p

oo

l (k

g m

-2)

Unpublished data kindly provided by Henning Meesenburg


0

20

40

60

80

100


S an

d N

dep

ositi

on (k

g ha

-1 y

r-1)

1968 1973 1979 1983 1987 1990 1991 1995 2001 20100

5

10

15

2.45 2.82 3.434.87 5.09 6.13 5.56 5.30 5.19

3.75

Forest floor mass

Forest floor C poolF

ore

st f

loo

r O

M p

oo

l (k

g m

-2)

y=-0.102x + 208.45R2=0.91

y=-1.82x + 3659R2=0.85

Unpublished data kindly provided by Henning Meesenburg


- Forest floor C pool reduced by 39% since 1990

- Total S deposition reduced by 75% since 1990

Solling (Germany) spruce forest research plot:

dC/dS = 560

• It appears that past acidification caused the suppression of decomposition leading to the accumulation of a large pool of organic matter on the forest floor. The alleviation of this acidification pressure over the last two decades appears to have triggered the remobilisation of the soil C pool.

Conclusions

Why is dissolved organic carbon (DOC) important ?

• Important feature of many aquatic ecosystems with wide-ranging ecological impacts

– Effects on aquatic metabolism as a substrate for heterotrophic production

– Influence on primary production through light availability

– Resposible for transport of many organic pollutants and heavy metals

– Effects on water chemistry, e.g. pH

Vinnetou and Plitvice Lakes National Park in Croatia

Effects of acid deposition on DOC


• Most important form of organic carbon transport from terrestrial to aquatic ecosystems

– Global estimates of both annual riverine organic C transport and soil C sequestration rates are comparable, suggesting that riverine losses of organic C may regulate future changes in soil C storage

• Stream DOC flux may represent around 10% of the net ecosystem exchange (NEE) for boreal forests (Schelker et al., 2012) and 25% of the NEE for boreal bogs (Nilsson et al., 2008)

– Stream DOC may reflect changes in catchment C cycling

Estimated annual carbon budget for the Auchencorth catchment in Scotland Billett et al., (2004)

Lysina - temperate forest ecosystem in the Czech Republic

Annual C increment in tree biomass ¬ 1745 kg C ha-1 yr-1

Annual DOC flux – 97 kg C ha-1 yr-1 (6%)

Pg C yr-1

In-land aquatic component in the global C balance (Cole et al., 2007)


DOC has increased:

• In much of Europe and North America

• In lakes and streams

• In forests and moorlands

• In waterlogged and aerated soils

• At high and low flows

1988 1993 1998 2003 2008-2.0

-1.0

0.0

1.0

2.0

3.0

4.0Acid Water Monitoring Network (UK)

DO

C (

stan

dar

dis

ed c

on

cen

tra-

tio

ns)

1988 1993 1998 2003 2008-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0Drinking Water Reservoirs (CZ)

CO

D (

stan

dar

dis

ed

con

cen

trat

ion

s)

Prague 2002

Strong evidence of a relationship between acid deposition and organic matter solubility

Solubility of DOC is dependent on:

• Acidity• Ionic strength• Aluminium concentration

Decomposition of organic matter (which produces DOC) also affected by pH, …and N

Effects of acid deposition on DOC

Results from acidity manipulation experiment in UK

Acid treatment – H2SO4

Alkaline treatment - NaOH + MgCl2

Consistent, positive DOC response to pH change at all sites, which can be described by a simple, general relationship, such that a 1 unit increase in soil solution pH is sufficient to more than double DOC concentrations.

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2

Trea

tmen

t/co

ntro

l sta

ndar

dise

d D

OC

Treatment/control standardised H

Temporal coherence between SO4 declines and DOC increases in Central European catchments

Oulehle F. and Hruska J., 2009, ENVIRONMENTAL POLLUTION 157: 3433-3439

Evans C.D. ,2012, GLOBAL CHANGE BIOLOGY 18: 3317-3331


•Declining S deposition appears able to explain a large part of observed DOC trends.

• Therefore, rising DOC in well studied areas (Europe, USA) should not be misconstrued as evidence of rising DOC in unmonitored waters globally.

- threats of widespread destabilization of terrestrial carbon reserves by gradual rises in air temperature or CO2 concentration may have been overstated in

those areas.

• Past acid conditions may have reduced decomposition rates, allowing a pool of relatively labile organic matter to accumulate, from which DOC is generated as acidity decreases.

Conclusions

Linkages between DOC availability and soil heterotrophic respiration

Three mechanisms could lead to lower amount of bioavailable dissolved organic C (DOC) for the microbial community (Kopáček et al., 2013)

(1) Increased abundance of N for plant uptake, causing lower C allocation to plant roots(2) Chemical suppression of DOC solubility by soil acidification(3) Enhanced mineralisation of DOC due to increased abundance of electron acceptors in the form of sulphate and nitrate - in anoxic soil micro-sites.

Week 1 Week 2 Week 3 Week 4

Soil analysis Soil analysis

Leachate analysis Leachate analysis Leachate analysis

Treatment addition Treatment addition Treatment addition

CO2 measurements

Control H2SO4 HCl NaOH NaCl

800 ueq L-1



Solution applications had immediate effect on DOC concentration in soil water.

Ctrl H2SO4 HCl NaOH NaCl0

20

40

60

80

100

120

140

160

180

200soilwater DOC 1st treat

2nd treat3rd treat

mg/

L


1 27 53 79 1051311571832092352612873133390.7

0.8

0.9

1.0

1.1

1.2

1.3

NaOH

NaCl

H2SO4

Hour

Stan

dard

ized

soi

l res

pira

tion

(CO

2

flux)

1st treatment 2nd treatment 3rd treatment

Solution applications had immediate effect on DOC concentration in soil water and on soil respiration. In the end of the experiment, alkaline solution enhanced soil respiration by 20% compared to control, whereas acid treatment suppressed soil respiration by 15% compared to control. Neutral treatment has only short-term effect (suppression) on soil respiration.





those areas.


• Altered soil respiration is probably a direct result of DOC bioavailability for microbes under different treatments, rather then direct pH effect on soil microbial communities.

Conclusions

Effects of acid deposition on forest productivity

Growth depression under high acid deposition, and subsequent recovery following deposition reductions

Oulehle et al., 2011, GLOBAL CHANGE BIOLOGY 17, 3115-3129

Elling et al., 2009, FOREST ECOLOGY AND MANAGEMENT 257: 1175-1187

Results from Czech national forest inventories

18801890

19001910

19201930

19401950

19601970

19801990

20002009

1.0

1.5

2.0

2.5

3.0

tota

l ann

ual i

ncre

men

t (tC

ha-

1yr-1

)

• Annual above-ground carbon increment increased by 30% since 1950s

18801890

19001910

19201930

19401950

19601970

19801990

20002009

1.0

1.5

2.0

2.5

3.0

0

2

4

6

8

10

12

14

16

18

20

N deposition

tota

l ann

ual i

ncre

men

t (tC

ha-

1yr-1

)

N a

nd S

dep

ositi

on (k

g ha

-2 y

r-1)

dC/dN(1960-2010)=34

20-40 – de Vries et al., 200825 – Nadelhoffer et al., 199925-37 – Högberg et al., 200619 – Solberg et al., 20091880

18901900

19101920

19301940

19501960

19701980

19902000

20091.0

1.5

2.0

2.5

3.0

0

2

4

6

8

10

12

14

16

18

20

N depositionS deposition

tota

l ann

ual i

ncre

men

t (tC

ha-

1yr-1

)

N a

nd S

dep

ositi

on(k

g h

a-2

yr-1

)• In the European NITREX series of experiments, a 50% increase in tree growth was observed following experimental reduction of N and S inputs in N-saturated site (Emmett et al., 1998).

Effects of acid deposition on forest productivity

BUT

dC/dN(1960-1990)=10dC/dN(2000-2010)=154





those areas.



• Growth reduction of conifer forests in Central Europe has been observed between the 1960s and 1980s.

• During recent decades a distinct increasing growth trends were observed. This trend might only be explained if climate, fertilization by N-deposition, and the strong reduction of SO2 pollution are taken into account.

Conclusions

Modelling C and N dynamics using new version of MAGIC model

MAGIC (Model for Acidification of Groundwater In Catchments)

-Developed to predict the long-term effects of acidic deposition on surface water chemistry

-Model simulates soil and surface water chemistry in response to changes in drivers such as deposition of S and N, land use practices, climate…

- As sulphate concentrations have decreased, in response to the decreased S deposition, nitrate (NO3) has become increasingly important. In acid soils much of the NO3 leached from soil is accompanied by the acid cations H+ and inorganic aluminium (Ali)

-In the early versions of MAGIC retention of N was calculated empirically as a fraction of N deposited from input-output budgets

-Later on fraction N retained was described as a function of the N richness of the ecosystem (soil C/N ratio in this case)

-Alternative formulation of N retention in new version of MAGIC is based directly on the microbial processes which determine the balance of N mineralization and immobilization

Soil Organic Matter Carbon fluxes

FC0 = organic C f rom N-f ixersFC1 = organic C f rom plant litterFC2 = organic C processed in SOM turnoverFC3 = C in new microbial biomass (new SOM)FC4 = SOM C respired (CO2 in soil solution)FC5 = SOM C solubilized (DOC in soil solution)

Soil Organic Matter Nitrogen fluxes

FN0 = organic N f rom N-f ixersFN1 = organic N f rom plant litterFN2 = organic N processed in SOM turnoverFN3 = N in new microbial biomass (new SOM)FN4 = SOM N mineralized (NH4 in soil solution) FN5 = SOM N solubilized (DON in soil solution)FN6 = organic N f rom SOM used by microbesFN7 = inorganic N immobilization by microbes

Soil Solution Carbon & Nitrogen Fluxes

fC1 = organic and inorganic C in runof f fC2 = inorganic C exchange with the atmosphere

fN1 = organic and inorganic N in runof ffN2 = inorganic N uptake by plantsfN3 = denitrif ication of inorganic N fN4 = atmospheric deposition of inorganic N

PlantsN2

CO2

fN2

FN7

FC4

FN4

Soil Organic Matter

(SOM)

SOC, SON

Microbial Turnover FN5

FC5

FC1 FN1

litter

NO3, NH4

NO3 NH4

FN2

FC2

FN3

FC3

uptake denitrification

nitrification

immobilization

mineralization

runoff

deposition

fN3 fN4

CO2

gas exchange

respiration

fC2

FN6

N- Fixers

FC0 FN0

fC1 fN1

Dissolved Organic Material

(DOM)

DOC DON

-Inorganic N enters the model as deposition (wet and dry)- Time series of plant litter and N fixation (FC1 and FC2) are external inputs to SOM. At each time step, decomposers process some of the C and N content of SOM (FC2 and FN2). A portion of this C and N turnover returns to the SOM as decomposer biomass (FC3 and FN3), while the remainder is lost from SOM as CO2 and NH4 (FC4 and FN4) or as DOC and DON (FC5 and FN5).

1940 1960 1980 2000 20200

100

200

300

400

1940 1960 1980 2000 20200

10

20

30

40

50

1940 1960 1980 2000 20200

20406080

100120

NO

3- (µ

eq l-

1)

- Lake, stream and soil water chemistry (nitrate) from different catchments in the Czech Republic

MAGIC application on three long-term monitoring sites in the Czech Republic

1940 1960 1980 2000 20200

100

200

300

400

1940 1960 1980 2000 20200

10

20

30

40

50

1940 1960 1980 2000 20200

20406080

100120

NO

3- (µ

eq l-

1)

- Constant carbon turnover

1940 1960 1980 2000 202005

1015202530

0

20

40

60

80

100

Carb

on fr

actio

n pr

oces

sed

(%)

Ali

conc

entr

ation

(um

ol+/

L)

1940 1960 1980 2000 202005

1015202530

020406080100120140

1940 1960 1980 2000 202005

1015202530

0

200

400

600

800

1000

- Adjusted carbon turnover based on Ali concentration

1940 1960 1980 2000 20200

100

200

300

400

1940 1960 1980 2000 20200

10

20

30

40

50

1940 1960 1980 2000 20200

20406080

100120

NO

3- (µ

eq l-

1)

Oulehle F., Cosby B.J., Wright R.F. et al., 2011, ENVIRONMENTALL POLLUTION 165, 158-166

Modelling C and N dynamics using new version of MAGIC model





those areas.





• Acidity changes in forest ecosystems might have a strong confounding influence on ecosystem sensitivity to eutrophication, with acidification accelerating N saturation (nitrate leaching), and recovery potentially resulting in reversion to N limitation (nitrate retention).

Conclusions





those areas.





• Acidity changes in forest ecosystems might have a strong confounding influence on ecosystem sensitivity to eutrophication, with acidification accelerating N saturation (nitrate leaching), and recovery potentially resulting in reversion to N limitation (nitrate retention).

Conclusions

THANK YOU FOR YOUR ATTENTION

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Acidification constraints on carbon and nitrogen (mainly soil) dynamics Filip Oulehle, Chris Evans,...

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