LIGNUM: Towards Forest Scientist's Workbench

1. LIGNUM: Towards Forest Scientist's Workbench Jari Perttunen1 Risto Sievänen1 Eero Nikinmaa2 1. The Finnish Forest Research Institute 2. University of Helsinki (Dept. of Forest Ecology)

2. CONTENTS • The Model LIGNUM • Current Applications • Modeling Sugar Maple • The Design and Implementation of the Forest Scientist's Workbench

3. LIGNUM: General features • Simple structural units describe both structure and functioning of trees. • Carbon budget models the metabolism: • Annual net production is used to new growth. • Pipe model and functional balance steer growth. • Time step one growth period (one year).

4. LIGNUM: Structure • Capture the structure of a tree with simple structural units: • Tree Segment (TS) • Branching Point (BP) • Bud (B) • Axis (A)

5. LIGNUM: Tree Segment • Structure: • Dead heartwood (H) • Living sapwood (S) • Bark layer (BL) • Foliage (F) • Tree segment is the main functioning unit. F S BL H

6. LIGNUM: Deciduous trees • Explicit leaves instead of cylindrical layer of foliage: • Leaf ellipse, use parameter to denote "degree of filling". • Track the 3D position of each leaf. • Dormant (suppressed) buds.

7. LIGNUM: Releasing suppressed buds • Maintain the structural integrityof the model: • Split the segment into two. • Insert a new branching point. • The released bud will become the terminating bud in the new axis.

8. LIGNUM: Implementation

9. LIGNUM: Carbon balance

10. LIGNUM: Segment length

11. LIGNUM: New buds

12. LIGNUM: Pipe model

13. LIGNUM: The Radiation Submodel Z • Standard overcast sky. • Divide the sky into sectors and assign each sector a radiant intensity. • Number of inclinations and azimuths can be defined by the user. Y X MJ

14. LIGNUM: The Radiation Submodel Shading • Coniferous trees: • Compare segments to compute the distances light beams travel in foliage. • Compute attenuations of radiation. • Compute intercepted radiation. • Compute photosynthesis. • Deciduous trees: • Compare leaves. Shaded

15. Voxel space: Alternative radiation model

16. LIGNUM: Applications Scots pine Sugar maple Mountain birch Gliricidia sepium

17. Scots pine • Scots pine and Jack pine the first two tree species implemented. • Proved the modeling approach feasible. • Modeled (published) trees 10 years old.

18. Mountain birch • Structural analysis of mountain birch • Based on detailed measurements done in Finnish Lapland • Position and orientation of each segment known. • Position of leaves known.

19. Gliricidia sepium • Nitrogen fixing tropical tree species used in agroforestry. • Study the optimal management (frequency of cuttings).

20. Analysis of Daily Sapflow

21. Sugar maple • Study the survival and growth of sugar maple saplings in forest gaps. • Long term goal to develop new cutting guidelines for natural regeneration of sugar maple: • Size of the canopy openings • Frequency of cuttings

22. Modeling Sugar maple in forest gapsSt-Hilaire, Quebec • Typically when modeling tree species with LIGNUM the following growth processes are assessed: • Metabolism: • Photosynthesis, respiration. • Structural Dynamics: • Birth, growth and senescence of tree compartments. • Tree Architecture: • Currently ad hoc descriptions.

23. Modeling Gaps in St-Hilaire • Field data: radiation measurements and fish-eye photographs from the gaps. • Analysis of field data resulted masks (Closed Gap and Open Gap) that can be superimposed on SOC. Masks SOC for St-Hilaire

24. Diameter Growth (Pipe model) • For newly created segments sapwood must support foliage. Af Asf = SLA ´ U For other segments match the sapwood coming above. Anew = max[Asu + dAs + Ah, Ats]

25. Parameters • Search, deduce and compile parameters from various sources (or make your best guess)

26. Three 5 year old saplings in St-Hilaire L = 2.84m L = 2,43m L = 1.37m Open Gap Released Zenith Closed Gap

27. LIGNUM: Scientist's Workbench

28. Sample Program Class Hierarchy 1.#include <Lignum> 2.using namespace Lignum; 3. 4. int main() 5.{ 6. Tree<ScotsPine> t1; 7. Tree<Birch> t2; 8. Tree<Birch,BirchBud> t3; 9. double p,m; 10. 11. t1.growth(5); 12. ForEach(t2,P<Birch>()); 13. ForEach(t2,M<Birch>()); 14. p = Accumulate(t2,0,CP<Birch>()); 15. m = Accumulate(t2,0,CM<Birch>()); 16. PropagateUp(t2,p-m,Allocate<Birch>()); 17. 18. exit(0); 19.} TreeCompartment B Tree A TS BP HwTS BirchBud CfTS Birch ScotsPine ScotsPine<TS,BUD>::P() { p = Po*I; } Birch<TS,BUD>::P() { for_each(leaves,p()); }

29. Concluding Remarks • To develop LIGNUM to a Forest Scientist's Workbench use simple, independent and easily customizable workbench components. • C++/OpenGL implementation is available on: • SGI IRIX, Linux, (Microsoft Windows NT). • Computer graphics aid understanding and presenting the results of simulations: • In the future the Virtual Reality can be used.

30. LIGNUM in HUTCAVE Virtual Room

31. www.metla.fi/projects/lignum