Tree List Generator TLG v1.0

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Tree List Generator (TLG)v1.0

• Kevin R. Gehringer
• Eric C. Turnblom

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TLG - Topics

• Introduction / background
• Models / Methods
• Results / Discussion
• Operation / Output
• Future work / conclude

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TLG - Introduction

• Initial tree list estimation for individual tree
  based growth models
• Basically targeted use of the SMC-ORGANON
  modeling database to develop a methodology for
  generating initial tree lists
• Tree List Generation Database software provides a
  means for producing reasonable tree lists for a
  forest stand based on a minimal amount of
  information, such as SI, age, TPA, etc.

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TLG - Introduction (2)

• Tree list is a compatible set of DBH and height
  measurements for each tree as well as species
• TLG is designed for managed, mixed species stands
  of Douglas-fir and western hemlock as dominant
  species (with mixtures of other minor species)
• Untreated stands and thinned stands throughout
  southwestern British Columbia, Washington and
  Oregon west of the Cascade Crest

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TLG - Introduction (3)

• Tree list generation requires four things
• A method for classifying stands
• A method for selecting an appropriate stand class
• A method for generating a tree list from a stand
  class
• A wide variety of stand measurement data sets
• Useful to think under the framework of generating
  a random stand of trees using a small set of
  stand attributes as the seed

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TLG - Methods

• Weibull density distribution based methods
• Weibull is strongly unimodal
• Represents flat distributions poorly
• Mixed species stands present challenges
• Parameter prediction functions may change with
  new data
• Non-parametric, density estimation methods (e.g.,
  B-splines, etc.)

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TLG - Methods (2)

• Tree List Generation Database method
• Explicit classification based on a
  multidimensional histogram (data speaks for
  itself)
• Histogram is a consistent estimator of a density
  function
• Histogram allows refinement of its classification
  if sufficient data warrant higher resolution
• Histogram does not require reevaluation of
  classification rules when new data is added
• Histogram dimensions are stand attributes, e.g.,
  site index, QMD, stand type, etc

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TLG - Methods (3)

• Tree List Generation Database method (contd)
• Stands with similar attributes belong to same
  hist. Bin
• Given a set of desired stand attributes,
  similarity scores are calculated for stands
  defined by the tree list generation database
• The k smallest similarity scores are used to
  select the collection of stands to form the
  canonical stand from which a tree list may be
  generated

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TLG - Methods (4)

• Two fundamental assumptions
• Forest stands, or sample plots, having similar
  attributes, e.g., site index, QMD, species
  composition, etc., are similar
• Attributes of forest inventory data collected
  from a representative set of sample plots from
  within a larger stand may be extended to the
  whole stand

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TLG - Results

• Simulated stands generally agreed with the actual
  stands they were generated to mimic at the
  individual tree level defined by DBH, height and
  species
• Based on a single random draw
• For DBH alone, misclassification rate was 2.6
• For height, misclassification rate was 13.2
• For species comp., misclassification was 8.3

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TLG - Operation

• Conventional DOS command line interface
• Stand Description files specify input values for
  the set of measured or desired attributes used as
  the histogram bin dimensions for which a
  simulated tree list is desired
• comments appear after a sign
• KEYWORD VALUE format defines desired
  attributes

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TLG - Operation

• Example stand description file
• TREATMENT_TYPE UNTREATED
• SITE_INDEX 140.0
• STAND_TOTAL_AGE 57.0
• STAND_ORIGIN NATURAL
• STAND_DENSITY 160.0
• QMD 12.6
• STAND_TYPE PURE_DF

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TLG - Operation

• Random Measurement files are produced by the tree
  list generation process and contain attributes
  for the stand and a simulated stand of trees
• Three files are needed to set up or change the
  stand classification attributes
• Schema file defines multidimensional histogram
  bin dimensions
• Species mapping file maps 2-6 char. Code to
  integer
• Stand measurement file added to tree database

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TLG - Future work

• Add new Type I and Type III data to the set of
  stand measurement files included in the tree list
  generation database distribution set
• Add Graphical User Interface (GUI) such as is
  used with DFSIM, that is, DFSIMIN

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TLG - Possible GUI
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Tree List Generator

• Please visit lthttp//www.standmgt.org/gt
• Click on the SOFTWARE link on L.H.S.
• Questions / Comments ?

Kevin R. Gehringer Eric C. Turnblom