Transcript Stretch: a spatially explicit individual based forest

Stretch: a spatially explicit
individual based forest
simulator
L.Soler, D. Harja Asmara,
M. Laurans, C.Madeleine, J.Dauzat,
G. Vincent, F. de Coligny
Montpellier, France
Model porting
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From Sexi-FS (Degi Harja Asmara, Grégoire
Vincent)
Increase the versatility/genericity of the model
Modifications of processes
Use functionalities of Capsis
Transfer
Plasticity is one of the major axis of the
laboratory AMAP
 Two Phd student work on this subject
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Stretch
Spatially explicit
 Individual based
 Multi species
 3D
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Crown shape plasticity
 Light
 Space limitation
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The yearly simulation loop
Initialisation step
Environnement settings
Scene initialisation (trees, terrain)
Species initialisation (reference tree growth)
Regeneration
mechanical constraints
(BIOMECHANICS)
light availability
(MMR,SLIM,Liebermann)
mortality
Legend:
Red : additional
options to the model
with crown
Black : model
without considering
the crown
Tree overall dimension
change, Crown deformation,
phototropism, collision
Process
Growth
Stem Growth algorithm
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dbh function : Chapman Richards function
Growth of stem volume :
Ln(vol(t)) = u + v*ln(dbh(t))+w*ln(h(t))
Growth Reducer
Current volume
Potential volume
Increment
New Volume
Light
New height
New dbh
Crown growth
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Depends on the stem growth
Virtual vectors of branches
Polygones
Lieberman
Calcul of the index of closure of the canopy : G
 G caracterises the light environment
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Δhi = hi - h
hpi = √(d²i+Δh²i)
sinΘi = Δhi /hpi
G = Σi sinΘ
M. Lieberman, D. Lieberman, R. Peralta, G.S. Hartshorn, 1995,
« Canopy closure and the distribution of tropical forest tree species at La Selva, Costa rica »,
Journal of Tropical Ecology, 11:161-178
Calcul of Light Growth Reducer
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The index G by interpolation will determine the
Light Growth Reducer (LGR)
1.2
1-LGR
1
0.8
shade tolerant
0.6
light demanding
0.4
shade specialist
0.2
0
-0.5
0
-0.2
0.5
1
1.5
G
Mortality algorithm
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Primary mortality
- vigour (survival probability,
growth reducer, mortality function)
- senescence (dbhMax,
volumeMax, heightMax…)
Graphic interface
To do
Alternative algorithm for dbh growth
 Alternative algorithm for height/dbh allometry
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Primary mortality (add biomecanics constraints)
 Secondary mortality
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Regeneration
 3D viewer
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To do
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Crown deformation module
- assymetric crown shape deformation
- crown grow to reach the light
• Deformation can be local (radial
anisotropy of light and available
space)
• Local deformation is modeled via a
set of independent vectors stemming
from crown base subtending the crown
envelope
SLIM and MMR
SExI-FS Scene
Simple Light Interception Model
(SLIM)
This method is similar to hemispherical
photographs, which are normally taken at
ground level.
A computed canopy openness compared
to the real location in the forest.
Shape transformation
response of trees in crowded
habitats (STReTCH)
MMR
MMR: one module in Archimed
simulator
measurements
Remote
Sensing
Light partitioning
PAR
NIR
TIR
Micrometeo.
Data Set
BRDF
LIDAR
TIR Emittance
Incident radiation
Turbulent transfers
Air profiles
RHair Tair
wind
irradiation
temperature
lE
transpiration
H
Ws, Wr
RHair
H
Ts, Tr
Cartography of soil irradiance, temperature and humidity
sap flow
Tair
lE
Yleaf
photosynthesis
MIR
MUSC
Incident radiation
Multiple scattering
Meteo.
Meteo.
RADBAL
data
details
Radiation balance
light
on
soil
plant
Irradiation
scene
rad.
balance
Basic principle of MIR
All objects
you can see
when back to
the sun are
sunlit
Basic principle of MIR
Discretisation of incident radiation
Splitting sky
hemisphere
with the
"TURTLE"
model
Mapping leaf irradiation
The total leaf irradiation is
obtained by weighting
its partial irradiation
from each source
Échelles de modélisation
modèles numériques multi-échelles
SExI-FS Scene
Mir images
MMR
Virtual plot duplication
2
3
1
1
The projections
of plants
are moved
modulo the
dimensions
of the scene
2
3
LAYERS
0
Information for each pixel
1
Altitude first hit
Nb hits in layer 1
2
3
Nb hits in layer 2
Nb hits in layer 3
MuSc : calcul des "MUltiple SCattering
The MUSC
model is
based on
light
interception
probabilities
output by
the MIR
model
Daily irradiation