Tree and Stand Simulator (TASS)

Tree and Stand Simulator (TASS)

2005 FSP Projects

Stand Development Modelling Group

Research Branch, B.C. Min. of Forests

Stand Development Modelling GroupSDMG:

– Jim Goudie (Research Leader SDMG)

– Ken Mitchell (scientist emeritus)

– Catherine Bealle Statland (complex stand development)

– George Harper (stand development – hardwoods)

– Mario Di Lucca (G&Y applications specialist - TIPSY)

– Abdel-Azim Zumrawi (biometrician – PrognosisBC)

– Ken Polsson (programmer/analyst)

– Dave Simpson (research scientist - ecophysiology)

– Peter Fielder (field biologist – light measurements)

– Shelley Grout (software application specialist - TIPSY)

.Tree And Stand Simulator (TASS)

Table Interpolation Program for Stand Yield (TIPSY)

Field data

TASS

Silvicultural decisionsTimber supply projections

Research Operations

New questionsAdditional species(hardwoods, etc.)Complex standsAdditional variablesDifferent treatments

Calibration &Visualisation oftreatment regimes

Group retention

Uniform shelterwoodStrip shelterwood

Traditional clearcut

TIPSY

Key TASS components - operational version

• Height Growth = f(potential, light)• Crown morphology

– Branch extension– Branch angle– Branch diameter– Foliage (biomass, leaf area)

• Crown Competition• Mortality• Ring characteristics (juvenile-mature wood, size,

relative density, strength, cell characteristics)• Genetics

Height growth

0 20 40 60 80 100 120 140 160

Total age (years)

0

10

20

30

40

50

60Top height (m)

Site trees

Average tree

Low vigor trees

1.0

0.8

~0.6

TASS II - Operational version

Dead tree

Live trees,

Critical distance}

Bole increment

0 50 100 150 200 250

Foliar volume (cu.m)

0

0.1

0.2

0.3

0.4Bole increment (cu.m)

Open grown

Suppressed

(with estimates of juvenile-mature wood contents)

Calibration

EP 703 control plotsCoastal Douglas-fir

Variable retention using TASS II

Strip shelterwood Uniform shelterwood

Group retentionTraditional clearcut

Retained stand age 100 years - Regenerated stand age 10

Traditional clearcut


Group retention








Strengths of the TASS - Operational (TASS II) version

• Biological foundation– Tree crown focus– Spatially explicit – Graphic visualisation (no black box)– Amenable to linkage with other models– Extrapolations are usually reasonable (e.g. variable retention)

• Peer reviewed (Forest Science Monograph 17, 1975)

• Supported by extensive permanent sample plot database– BC species (>15,000 plots)– PSPs from BC & other provinces, PNW, Europe, Scandanavia,

New Zealand

TASS versions

• TASS-II– a spatially explicit, individual tree based model driven

by height growth, crown expansion and bole increment (Mitchell 1975).

• TASS-III– a multi-canopy version of TASS-II that includes a light

model (tRAYci) enabling the simulation of understorey light levels and plant growth.

TASS II TASS III

TASS III - 3D Canopy Grid

TASS III - color, actual plots and light model (tRAYci)

tRAYci Light model

2005 FSP Projects

• 6 approved FSP multi- year projects– 4 new in 2005– 2 in second year, initiated 2004

• See handout for project leader information

• Concerns: capacity & salary recovery

FSP Funding

Continuing

• Lodgepole pine wood quality (Jim Goudie)Goal: predict wood quality attributes under various management strategies.

• 60 Pl destructively sampled from interior BC (branch, crown, foliage and bole measurements)

• Determination of wood quality attributes (relative density of early wood / late wood, micro-fiber angle)

• wood quality prediction parameters incorporated into TASS II & SILVER

FSP FundingContinuing

• Light and tree growth in complex forest stands(David Simpson)Goals: (1) augment TASS height growth models using relationships between tree height growth and light levels, and (2) test model estimates of light levels and tree growth in real forests.

• Last year: Tree growth measurements and light estimates from hemispherical photos and LAI2000 readings for Douglas-fir and western hemlock saplings; model testing in a partially cut interior Douglas-fir stand.

• Next 2-years: Additional measurements for Douglas-fir, hemlock, interior spruce and lodgepole pine; model testing in coastal stands under variable retention (STEMS research site)

FSP FundingNew 2005

• Variable Retention Harvesting and Forest Level Modelling (Mario Di Lucca )

Goal: improve our ability to predict the impact of variable retention harvesting (VR) in Provincial timber supply analysis by adding VR functionality to the Forest Service Spatial Analysis Model (FSSAM).

• Create TASS II datasets and develop VR functions that specifically address FSSAM parameter needs for coastal Douglas-fir, western hemlock, white spruce, and lodgepolepine.

• Requires TASS runs for a matrix of different forest types, crown layers, age classes, stand heights, site indices, tree cover patterns, and retention types and percentages. Key outputs are perimeters of the retained overstory trees or tree groups used to estimate the VR adjustment factors (VRAFs).

Clearcut

Cutblock Area: 31 haCrown Cover: 14%

> 15 aggregated groups: 0.05 to 2.1 ha

Avg. group size: 0.3 haRetained top height: 30 mEdge length : unknown

TIPSY ver. 3.2

0.82

Average Reduction

1.00

VR

VRAF = VR vol/Clearcut vol = 0.82

FSP FundingNew 2005

• Modelling windthrow after variable retention harvesting (Mario Di Lucca)

Goal: to incorporate the effects of windthrow after VR harvesting into TASS III and TIPSY .

• First step: develop empirical functions to account for windthrow at the stand level (Steve Mitchell, UBC).

• Next step: link TASS III with the FOREST GALES model (UK Forestry Commission) to allow tree level predictions.

• Last: incorporate TASS III FOREST GALES information into TIPSY.

FSP FundingNew 2005

• TASS III: Simulating the management, growth and yield of complex stands (Jim Goudie)

Goals: (1) integrate new and revised modules into a new version (TASS III) designed for uneven-aged and mixed-species stands, and for complex treatments, and (2) release an executable version. Modules to be revised and fully integrated include:

• TASS III (3-D canopy grid that accommodates multi-layered structures)

• tRAYci raster-based light model (Brunner 1998)• TIPSY user input interface • VISTASS (Visual Interpretation of Silvicultural

Treatments and Stand Structures) stand visualization application

FSP FundingNew 2005

• TASS III: Simulating the management, growth and yield of complex stands (continued)

We expect to deliver the following new features:–Realistic and accurate predictions for complex stand structures (e.g., multi-species, multi-cohort, spatially heterogeneous), and complex treatments (e.g., Variable Retention , partial cutting, clearcutting-with-reserves) for select species;–Capacity to assess light levels (e.g., light maps before and after partial cutting);–User friendly and familiar front end similar to TIPSY interface;–Visual display of thinning/partial harvesting with the capacity to view the trees from different positions above or within the stand, and zoom in on features of interest.

FSP FundingNew 2005

• Modelling boreal mixedwoods (spruce-aspen-pine) with TASS. (George Harper)

• Incorporate TASS II aspen yields into the TIPSY database.• Compiled information linking understorey tree growth (height

and diameter growth, crown form and expansion) with stand light dynamics will be used to develop first approximation TASS III growth functions.

• Years 2-3 will include collection of additional field data that relates understorey tree growth to light levels and stand attributes. We will focus efforts at previously established boreal and sub-boreal mixedwood research sites.

Goal: to increase our understanding of understorey tree growth within aspen-spruce, aspen-pine mixedwoods and, extend this knowledge through developing TASS III growth curves and calibrating TASS III boreal mixedwood simulations .

TASS aspen calibration

• 2001 & 2002 tree level destructive sampling (51 trees)

• stand level data acquisition (Canadian and US sources)

• TASS spatial modelling for exploration of aspen regeneration performance - FG issues

• Tree level growth parameter development

TASS 2005 FSP Projects

END of Presentation

Documents

Tree and Stand Simulator (TASS)