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Stretch: a spatially explicit individual based forest simulator

Montpellier, France. Stretch: a spatially explicit individual based forest simulator. L.Soler, D. Harja Asmara, M. Laurans, C.Madeleine, J.Dauzat, G. Vincent, F. de Coligny. Model porting. From Sexi-FS (Degi Harja Asmara, Grégoire Vincent) Increase the versatility/genericity of the model

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Stretch: a spatially explicit individual based forest simulator

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  1. Montpellier, France Stretch: a spatially explicit individual based forest simulator L.Soler, D. Harja Asmara, M. Laurans, C.Madeleine, J.Dauzat, G. Vincent, F. de Coligny

  2. Model porting • 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

  3. Stretch • Spatially explicit • Individual based • Multi species • 3D • Crown shape plasticity • Light • Space limitation

  4. Initialisation step Environnement settings Scene initialisation (trees, terrain) Species initialisation (reference tree growth) mechanical constraints (BIOMECHANICS) Regeneration light availability (MMR,SLIM,Liebermann) mortality Process Growth Tree overall dimension change,Crown deformation, phototropism, collision The yearly simulation loop Legend: Red : additional options to the model with crown Black: model without considering the crown

  5. Stem Growth algorithm • 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

  6. Crown growth • Depends on the stem growth • Virtual vectors of branches • Polygones

  7. Lieberman • Calcul of the index of closure of the canopy : G • G caracterises the light environment Δhi = hi - h hpi = √(d²i+Δh²i) sinΘi = Δhi /hpi G = ΣisinΘ 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

  8. 1.2 1 0.8 shade tolerant 0.6 light demanding 0.4 shade specialist 0.2 0 -0.5 0 0.5 1 1.5 -0.2 Calcul of Light Growth Reducer • The index G by interpolation will determine the Light Growth Reducer (LGR) 1-LGR G

  9. Mortality algorithm • Primary mortality - vigour (survival probability, growth reducer, mortality function) - senescence (dbhMax, volumeMax, heightMax…)

  10. Graphic interface

  11. To do • Alternative algorithm for dbh growth • Alternative algorithm for height/dbh allometry • Primary mortality (add biomecanics constraints) • Secondary mortality • Regeneration • 3D viewer

  12. To do • 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

  13. SLIM and MMR

  14. SExI-FS Scene

  15. 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.

  16. Shape transformation response of trees in crowded habitats (STReTCH)

  17. MMR

  18. MMR: one module in Archimed Remote Sensing simulator measurements Light partitioning PAR NIR TIR Micrometeo. Data Set BRDF LIDAR TIR Emittance Incident radiation Turbulent transfers Air profiles RHair wind Tair irradiation temperature lE transpiration H photosynthesis Yleaf Tair sap flow RHair lE H Ysoil Wsoil Cartography of soil irradiance, temperature and humidity Ws, Wr Ts, Tr

  19. Meteo. details MIR Incident radiation MUSC Multiple scattering Meteo. data RADBAL Radiation balance light on soil plant Irradia- tion scene rad. balance

  20. Basic principle of MIR All objects you can see when back to the sun are sunlit

  21. Basic principle of MIR

  22. Discretisation of incident radiation Splitting sky hemisphere with the "TURTLE" model

  23. Mapping leaf irradiation The total leaf irradiation is obtained by weighting its partial irradiation from each source

  24. Échelles de modélisation modèles numériques multi-échelles

  25. SExI-FS Scene

  26. Mir images

  27. MMR

  28. Virtual plot duplication 2 3 1 1 The projections of plants are moved modulo the dimensions of the scene 2 3

  29. LAYERS Information for each pixel 0 Altitude first hit 1 Nb hits in layer 1 2 Nb hitsin layer 2 3 Nb hitsin layer 3

  30. MuSc : calcul des "MUltiple SCattering The MUSC model is based on light interception probabilities output by the MIR model

  31. Daily irradiation

  32. MMR CAPSIS Merci

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