LPJ-GUESS • Vegetation state representation • Plant functional types • Processes • Application examples • Trends and outlook in large-scale ecosystem modelling a large-scale ecosystem model NGEN02 Ecosystem Modelling 2019
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LPJ-GUESS
• Vegetation state representation
• Plant functional types
• Processes
• Application examples
• Trends and outlook in large-scale ecosystem
modelling
a large-scale ecosystem model
NGEN02 Ecosystem Modelling 2019
LPJ-GUESS population mode – typical representation of vegetation
in a DGVM of intermediate complexity*
Modelled area (grid cell) c. 100-2500 km2
Average individual
for PFT population
PFT 1 PFT 2 PFT 3 uncolonised
fractional cover (FPC) PFT
Average individual for PFT population
tree grass
crown area
height
fine roots
leaves
LAI
sapwood
heartwood
0-50 cm
50-100 cm
leaves / LAI
fine
roots
stem
diameter
*Sitch et al. 2003 Global Change Biology 9: 161-185
Average individual for PFT or species cohort
in patch
Modelled area (stand) c. 10 ha - 2500 km2
replicate patches in various
stages of development
Patch
0.1 ha
tree grass
crown area
height
fine roots
leaves
LAI
sapwood
heartwood
0 - 50 cm 50 - 100 cm
leaves / LAI
fine roots
stem diameter
crown area
height
fine roots
leaves
LAI
sapwood
heartwood
sapwood
heartwood
0 - 50 cm 50 - 100 cm
leaves / LAI
fine roots
stem diameter
Cohort mode – detailed representation distinguished
individual trees and patches with different disturbance histories*
*Smith et al. 2001 Global Ecology and Biogeography 10: 621
Parameter
max establishment
rate (ha1 yr1)
max longevity (yr)
survival in shade
optimal temp for
photosynthesis (°C)
bioclimatic
distribution
allocation to stem
growth
leaf:sapwood area
ratio (m2 cm2)
leaf phenology
crown spreading
boreal
10-25
evergreen
0.3
150
0.05
high
900
1250
temperate
15-25
summergreen
0.4
250
0.05
high
900
1250
boreal-temperate
10-25
summergreen
0.4
250
0.1
low
300
2500
no limits
10-30
summergreen-
raingreen
-
-
-
low
-
-
Trait differences influence functioning and interactions
among plant functional types / species
• Colonisation of unvegetated areas (primary succession)
• Inter- and intraspecific competition for light, space and soil resources
• Landscape as aggregate of stands / patches with differential history of disturbance, colonisation and succession
• Disturbances leading to complete or partial destruction of individual stands
• differential establishment, growth and mortality of species with alternative trade-offs between productivity and survivorship under stress
Elements of structural and compositional dynamics of vegetation
simulated by LPJ-GUESS b
iom
ass (kg
C m
2)
year
Hickler et al. 2004.
Ecology 85: 519-530
Coupled plant carbon and water balance
)(),,APAR(
),,(min max
maxVfR
TcfJ
TcVfJA leaf
iE
iC
n
leafNkV max
),( cai gcfc
soil water supply
PAR
APAR =
PAR · [1 exp( k · LAI )]
AET
Ci
AET
Ci
stomatal conductance, gc
gc
AET Monteith 1995 D
S
CO2
• physiological representation at leaf-level (modified Farquhar-model)
• light extinction in vegetation canopy (Beer’s law)
• humid boundary-layer increases stomatal conductance (Monteith 1995)
(Beer’s law)
Autotrophic (plant) respiration
RA = Rm + Rg
Temperature response of maintenance respiration Rm
Living tissue maintenance respiration
Growth respiration Rg = 1/3 of NPP
NPP = GPP Rm Rg
46
1
56
1309exp)(
TTg
)(N:C
TgC
rRm
Rg = 0.25 (GPP Rm)
Net primary production
T
Rm
T
Rm
SurfMetab (9) SurfStruct (4) SurfFWD (10) SurfCWD (11) SoilMetab (12) SoilStruct (5)
SurfaceMicrobial (8)
SurfaceHumus (7)
PassiveSOM (14)
SlowSOM (13)
SoilMicrobial (6)
C flow among soil C pools
Respiration flux to atmosphere when transfer carbon
Carbon flux to atmosphere due to fire (potentially lose, or wild fire)
Fire
CO2
CO2
CO2
CO2
CO2
Root (3)
NPP
Fire
Carbon flux to atmosphere due to fire (plant really burned)
f_1_metab(L/N) 1-f_1_metab(L/N) f_2_metab(L/N) 1-f_2_metab(L/N)
reprLeaf (1)Wood (2)
sapwood heartwood
Carbon allocation
Tree allometry and carbon allocation
Leaf-sapwood area ratio (Shinozaki et al. 1964)
Leaf-root mass ratio (functional balance)
Height-stem diameter relationship (forestry literature)
Diameter-population density relationship
(Reineke 1933)
rootlrleaf CkC
3/2
2 DkH
SAkLA lasa
D
H
D
CA
average individual
structure accrued C
(annual NPP)
allometric constraints
’old’
structure
new
structure
3 / 5 1
−5/3
1
D k CA
N CA
D N
×
age
proportion of
cohort surviving to age
max sapling
establishment rate
juvenile
phase
adult
phase
recruitment-
juvenile growth rate relationship
maximum
non-stressed longevity
Cohort mode population dynamics
resource-stress
mortality
constant parameter
dynamic process
Cover crop
Irrigation
Yearly cutting
Succession of abandoned farmland
PASTURE CROPLAND
NATURAL MGD. FOREST
Crop rotations
N limitation Land cover/land use
change (gross vs. net)
Continuous forestry
Daily grazing
Detailed forest management
Managed land version accounts for land use*
*Lindeskog et al. 2013. Earth System Dynamics 4: 385-407
Olin et al. 2015. Biogeosciences 12: 2489-2515
*Olin et al. 2015. Earth System
Dynamics 6: 745-768
Agricultural crop yields*
Sample applications of LPJ-GUESS
• Quantify and attribute uncertainty
GCM-derived uncertainty in future terrestrial ecosystem C balance
• Predict complex system dynamics
→ C-N interactions under future climate and CO2
• Account for biosphere-atmosphere feedback
evapotranspiration and albedo feedback in RCM-simulated future
climate
• Assess land use and management impacts
productivity and damage risk in Swedish forestry
N export to the Baltic Sea
=2300 Pg C
HI
LO
Simulating the land carbon cycle
GCP residual land flux 0.8 PgC
LPJ-GUESS
other DGVMs
Interannual variation in net ecosystem C balance
Ahlström et al 2015
Science
uptake
release
drought-induced anomaly 2005
Re
sid
ual l
and
C s
ink (
Pg
C y
r1)
LPJ-GUESS
Historical climate,
land use,
and CO2 data
Global terrestrial ecosystem C balance
under a ”business-as-usual” future climate scenario
from different climate models (GCMs)
Te
rre
str
ial e
co
syste
m C
po
ol (G
tC)
sink
source
neutral
Ahlström et al. 2012
Environmental Research Letters 7
LPJ-GUESS
RCP8.5
radiative
forcing
AR5 GCM
increased sink / reduced source
reduced sink / increased source
Robust patterns for some global regions
kgC m2 yr1
0.150
0.150
0
∆ Net ecosystem C balance
(2071-2100)(1961-1990)
Climate models ( GCMs )
Changes between 1971-1990 and 2071-2100
Ahlström et al 2012, Environmental research letters
latitude
earlier leaf-out → photosynthesis
milder autumn → respiration
increased productivity in parts of tropics
Some robust seasonal and regional trends
month
increased sink / reduced source
reduced sink / increased source
J F M A M J J A S O N D
increased sink / reduced source
reduced sink / increased source
Ahlström et al. 2012
Environmental Research Letters 7
total
uncertainty total
uncertainty
Te
rre
str
ial e
co
syste
m C
po
ol (G
tC)
sink
source
neutral uncertainty
due to factor A (e.g. NPP)
uncertainty
due to factor B (e.g. biomass
turnover)
remaining
uncertainty
LPJ-GUESS
RCP8.5
radiative
forcing
AR5 GCM
Contributions of individual model factors
to simulation spread
Factor Contribution to
uncertainty (%)
NPP 57
biomass turnover biome shifts 6
stand dynamics 2
wildfires 11
non-fire disturbance 3
environmental sensitivity of
soil respiration
21
Total 100
Anders Ahlström
unpublished data
Contributions of individual model factors
to simulation spread
Hungate et al. 2003
Science 302: 1512
Will the biosphere store more or less carbon under
future climate and CO2?
Smith et al. 2014
Biogeosciences 11: 2027-2054
LPJ-GUESS
model
nitrogen feedback reduces CO2 effect on C storage ...
... but climate change compensates via increased N mineralisation in warming soils
*Wårlind et al. 2014
Biogeosciences 11: 6131-6146
kgC m2 yr1
Additional C storage 1990-2100
due to C-N interactions
Increased stature, density and distribution of boreal forest
explains increased C sequestration*
latent heat
(evapo-
transpiration) sensible
heat
incoming
shortwave radiation
incoming
shortwave radiation
Vegetation cover and leafiness affect
partitioning of return heat flux from surface
– more latent heat reduces near-surface warming
sensible
heat latent heat
(evapotranspiration)
15
10
5
2.5
–2.5
–5
–10
–15
15
10
5
2.5
–2.5
–5
–10
–15
Feedback contribution
LEdynLEstat
Temperature change JJA °C
(2071-2100)(1961-1990) Tdyn
Latent heat flux change LEdyn
Feedback contribution TdynTstat
2000 2100 2020 2040 2060 2080
0
5
4
3
2
1
2000 2100 2020 2040 2060 2080
0
8
6
4
2
Leaf area index
LPJ-GUESS
RCA3
A1B
emissions
ECHAM5
Changed latent heat flux enhances summer warming in
southern Europe, dampens warming i central Europe*
*Wramneby et al. 2010. J. Geophys. Res. 115
Arctic vegetation feedbacks*
LPJ-GUESS
RCA4
RCP
forcing
EC-EARTH
Additional temperature change due to vegetation feedback
(2071-2100)(1961-1990)
*Zhang et al. 2014
Biogeosciences 11: 5503-5519.
• Seasonality shift – longer growing season, earlier temperature peak
• Evaporative cooling evens out growing season temperature profile
• Ecological implications?
Additional temperature change due to biogeophysical feedback
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
2000 2020 2040 2060 2080 2100
RCP26RCP45RCP85
(a)
Te
mp
era
ture
( C
)
-3
-2
-1
0
1
2
3
J F M A M J J A S O N D
(b)
Te
mp
era
ture
( C
)
∆T (
°C)
albedo feedback
evapotranspiration feedback
(2071-2100)(1961-1990)
*Zhang et al. 2014
Biogeosciences 11: 5503-5519.
Arctic vegetation feedbacks
latitu
de
( N
) la
titu
de
( N
)
Damage risk (m3 ha1)
Production (m3 ha1 yr1)
1961-1990 2071-2100
1961-1990 2071-2100
Effects of management choices
on forest productivity and damage risk*
*Jönsson et al. 2015
Mitigation & Adaptation Strategies for Global Change 20: 201-220
Management:
continuous cover forestry
+5-10% broadleaved trees
successively shortened rotation length
current forest management
Climate:
A1B scenario
Integrated assessment modelling framework
— from global scenarios to regional impacts
K. Engström
in prep.
*Engström et al. 2016
Biogeosciences Discussions
Socio
-econ
om
ic c
hallen
ges
for
mitig
ation
Socio-economic challenges
for adaptation
SSP5 – Fossil-fuelled
development
- Low population
- High economy - Material intensive
- Free markets, global trade - Rapid technological growth
SSP3: Fragmented world
- High population - Slow economy
- Material intensive - Regional security, trade barriers - Slow technological growth
SSP1 – Sustainability
- Low population
- Medium-high economy - Low material consumption - Sustainable development
- Rapid technologial change
SSP4 – Inequality
- Relatively high population - Low to medium economy
- High and low material intensive - Benefits the elite - Rapid to slow technological change
SSP2 – Current trends continue
- Medium population - Medium economy
- Material intensive - Weak sustainability - Medium technological growth
Scenarios of the future world
Shared socio-economic pathways (SSPs)*
*O’Neill et al. 2015
Global Environmental Change
Scenario assumptions lead to contrasting patterns of
future land use change
SSP1M
SSP2R SSP2M
SSP3M
Change in cropland cover
(2071-2100)(1971-2000) (fraction)
Mitigation forest conversion to bioenergy production
better technology and less people to feed reforestation
poor technology, low trade, high population expansion of agricultural land
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0
0.1
0.2
0.3
0.4
0.5
Increased N export in many scenarios
— climate mitigation ”helps” E
co
syste
m N
expo
rt (
TgN
yr
1)
sustainability
current trends continue
fragmented world
fossil-fuelled development
inequality
radiative forcing-climate uncertainty
c.f. 0.64 Tg total N load to the Baltic Sea in 2006 (HELCOM)
Note high sensitivity to scenario, radiative forcing and climate response
Trends in large-scale ecosystem modelling
• Nutrient (N, P) cycles, long-term response to elevated CO2
• Trace gases – methane, N2O, biogenic volatile organic compounds
(BVOCs)
• Crops, forest management, land use change
• Coupled component in global and regional Earth system models
(ESMs)
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