Impacts of changes in nitrogen deposition,
ozone exposure and climate on carbon
sequestration of forest ecosystems in Europe
Wim de Vries
Max Posch, Gert Jan Reinds, Luc Bonten and Dave Simpson
Contents
 Impacts and interactions of air quality and climate
change in forest carbon sequestration
 Model approach: EUgrow coupled with VSD+
 Scenarios and results for the period 1900-2050
 Conclusions
NP
P
= C Flux
Tree
C
= C Pool
ALP
= C Loss
C
ANPP
Ra
GPP
Harvest +
Fire
AWP
Tree
C
NPP
C
Rs
BWP
Soil
C
BNPP
RLP
C
C
Impacts of air quality and climate change
Carbon sequestration in forests is affected by interactions:
 Climate change
● Temperature
● Rainfall, radiation
 Air quality
● CO2 exposure
● Ozone exposure
● N deposition (N availability)
 Soil quality: Availability of water and other nutrients (P,
S, Ca, Mg, K)
Impacts CO2, N, O3 and climate on
productivity (NPP) and soil respiration (Rs)
Source: Kongoi, Bonten and De Vries (2012)
Interactions of air quality and climate
change
Evidence for interaction between those drivers of
carbon sequestration, such as:
 Increased water stress lead to stomatal closure, limiting
effects of CO2 and O3.
 CO2 increases N uptake by increased fine root biomass.
 N limitation inhibits the CO2 fertilization effect
 Elevated temperature enhances N effect by increased N
mineralisation.
Soil warming enhances N availability
Soil warming, Harvard
Forest
Melillo et al. (2002)
N availability limits CO2 effects
CO2 enrichment, Duke
Forest, Ambient CO2,
376 ppm
Elevated CO2, 550 ppm
Norby et al. (2010)
Impacts of interacting drivers

Interacting impacts of CO2 x N fertilization on Rs
Multiplicative model
Additive model
Source: Kongoi, Bonten and De Vries (2012)
EUgrow/VSD+/PROPS model chain
Climate
CO2
Ozone
Nitrogen
EUgrow
Clitterfall
Csequestration
tree
Nlitterfall
VSD+
pH
Csequestration
soil
PROPS
Plant species
occurrence
C/N
Modelling approach EUgrow model
 Environmental effects on tree growth, G, is calculated for the
period 1900- 2050 as a function of a reference growth, Gref,
and modifying factors:
G =Gref * fdrivers/fdrivers,ref
 Reference growth was based on most current data for 250
regions, 20 tree species in EFI data base (year 2005).
 Modifying factors are all empirically based and scaled to a
factor 1 in 2005, being the year at which the reference growth
is assessed; alternative to process based DGVMs.
Modelling approach EUgrow model
 Effects of drivers on tree growth for the period 19002050 are included in two combinations:
 Reference model (interactions CO2 exchange and
nutrients)
fdrivers= min {fCO2 * fTemp * fwater , fNnut } * fNtoxic * fO3 (Ref)
 Fully multiplicative model (no interactions)
fdrivers= fCO2 * fTemp * fwater * fNnut * fNtoxic * fO3
(Mul)
 In this study, we excluded limitation of Ca, Mg, K, P
Modifying factors EUgrow model
 Temperature: influence on CO2 exchange and plant
respiration: from C-Fix model.
 Water stress: ratio actual/potential evapotranspiration.
 N deposition: a trapezoidal growth response function.
 CO2 fertilization: logarithmic scaling factor
 O3 exposure: linear growth response to phytotoxic ozone dose
(POD), calculated by DO3SE model
Examples N deposition impacts on growth

Photosynthesis rates level off at 10-15
kgN ha–1yr–1 with no further change to 35
kgN ha-1yr-1 at 80 plots over globe
(Fleischer et al., 2013)

Switch from positive to negative growth
response to N deposition for 180 oak and
beech plots in Flanders 1901–2008 at
20–30 kg N ha−1 yr−1 (Kint et al., 2012).

Non-linear relation between growth (BAI)
and N deposition at about 300 ICP forest
plots with negative response near 35 kg
N ha−1 yr−1 (Etzold et al., in press).
Ozone modifying factors for forest biomass
Norway Spruce and Scots pine
Beech/Birch
1.2
1.2
y = -0.0101x + 0.9653
R² = 0.6282
0.8
Series1
0.6
min
0.4
max
Linear (Series1)
0.2
0
0
20
40
60
y = -0.0078x + 1.0027
R² = 0.7738
1
Relative NAI
Relative NAI
1
0.8
Relative NAI
0.6
min
0.4
max
0.2
Linear (Relative
NAI)
0
80
0.00
10.00
POD1 treat/yr
30.00
40.00
POD1 treat/yr
Norway Spruce and Scots Pine
Beech/Birch
1.2
y = -0.011x + 0.9963
R² = 0.6321
1
0.8
Series1
0.6
min
0.4
max
Linear (Series1)
0.2
0
0
10
20
30
40
50
60
Relative Total Biomass
1.2
Tota Biomass
20.00
1
y = -0.0061x + 1.013
R² = 0.6518
0.8
MM Relative total
biomass
0.6
min
0.4
max
0.2
0
0
10
POD1 treat/yr
20
POD1 treat/yr
Source: Emberson et al. (2015)
30
40
Linear (MM
Relative total
biomass)
Model application: forcing data for 1900-2050

Climate data (hourly or daily resolution)
● 1960-2050 ECHAM5 A1B-r3 RCA3 simulation. Includes bias correction
for daily temperature and precipitation
● 1901- 1960: random draws out of 1961-1970 ECHAM5 data

CO2 concentrations
● 1900-2005: measured (Antarctic ice and Mount Loa)
● 2005-2050: predictions based on IPCC SRES A1B scenario

EMEP model N deposition and O3 exposure (hourly or daily resolution):
● 1900-2000: Lamarque dataset
● 2000-2050L new GAINS emission scenarios http://www.iiasa.ac.at/
web/home/research/researchPrograms/Overview2.en.html.
Model experiments with variations in Climate,
CO2, N deposition and O3: 14 and 4 mandatory
Name
Climate
CO2
N deposition O3
1901-2050
1901-2050 at 1901-2050
S0Results of 1901-2050
intercomparison
to be presented
Zagreb
meeting
S1
1901-2050 1901-2050 1901-2050
1901
S2
1901-2050 1901-2050 1901
1901-2050
S3
1901-2050 1901
1901-2050
1901-2050
S4
1901
1901-2050 1901-2050
1901-2050
Changes CO2 concentration and annual
temperature in A1B scenario
Temporal development of CO2 (Etheridge et al 1996; Keeling and
Whorf, 2006) and annual average temperature (from Magnuz et
al, pers. comm). Overall average (red line) and averages in
three European regions (▼: North; ■: Central, ▲: South).
Changes N deposition and POD for A1B
scenario
Temporal development of average N deposition and average
POD1 in Europe (red line) and in three European regions (▼:
North; ■: Central, ▲: South). Area-weighted average over ca.
800,00 forest sites (mapping units)
Impacts of drivers on tree C sequestration:
effect of including interactions in model
Impacts of removing individual drivers on tree
C sequestration as calculated by EUgrow
Impacts of removing individual drivers on soil
C pools as calculated by VSD+
Cpool (g/m²)
So = reference
50000
s0
48000
s1
46000
s2
44000
s4
42000
40000
38000
36000
34000
32000
30000
1900
1920
1940
1960
1980
year
2000
2020
2040
S1 = O3 constant
S2 = N constant
S4 = Climate
constant
Contribution of individual drivers to tree and
soil C sequestration in reference model
2005/1900
2050/1900
Reference
Reference
Interactions
Interactions
Soil
Climate
Tree
Soil
Climate
O3
O3
CO2
CO2
N
-10%
Tree
N
0%
10%
Contribution drivers to C sequestration
increase (%)
20%
-10%
0%
10%
Contribution drivers to C sequestration
increase (%)
20%
Conclusions
 A multiplicative drivers impact model shows a 30% growth
increase in the period 1900-2005 and 2005-2050. In a model
including interactions, this is near 10 and 8% in both periods.
 The lower contribution of drivers in the approach including
interactions is mainly due to N limitation effects!. There is still
large uncertainty in the effect of interactions
 Nitrogen had the largest contribution in the past and climate
will have it in the future, compared to 2005 but compared to
1900 N remains most important.
Questions?
Impacts of individual drivers on tree C
sequestration in reference model
Contribution of individual drivers to tree and
soil C sequestration in reference model
Driver
% Change 1900-2005
% Change 1900-2050
Tree
Soil
Tree
Soil
11
13
14
17
CO2
8
-
9
-
O3
-9
-8
-8
-7
Climate
1
-1.5
5
-3
Interactions
Reference
-2
9
3.5
7
-2
18
0
7
N
Interactions tree is reference –N-CO2-O3-climate.
For soil it is CO2 + interactions
Interacting impacts of changes in air quality
and climate on plant species occurrence
Climate ↑
CO2 ↑
POD ↑
Ndep ↑
+/-
+/-
+
-
Clf
+/-
Growth
ΔCtree
+
+/-
Nlf
+/0
+
+
+/ΔCsoil
+/+/-
Respiration
+/-
+/+/-
+
C/N
NO3
+/pH
+/+/-
Plant species
occurrence
+/-
+/-
EUgrow/VSD+/PROPS model chain
Climate
CO2
Ozone
Nitrogen
EUgrow
Clitterfall
Csequestration
tree
Nlitterfall
VSD+
pH
Csequestration
soil
PROPS
Plant species
occurrence
C/N