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Comparing ORGANON & SPS. Using the Bakuzis Matrix Growth Model Users Group December 15, 2005 Dave Hamlin. The Bakuzis Matrix. Egolfs Bakuzis U. Minnesota Synecological Coordinates Named by Rolfe Leary North Central Station, St. Paul. (retired). The Bakuzis Matrix.
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Comparing ORGANON & SPS Using the Bakuzis Matrix Growth Model Users Group December 15, 2005 Dave Hamlin
The Bakuzis Matrix • Egolfs Bakuzis • U. Minnesota • Synecological Coordinates • Named by Rolfe Leary • North Central Station, St. Paul. (retired)
The Bakuzis Matrix • A framework for examining models • In the context of biological ‘laws’ • Useful for side-by-side comparisons • Leary, R.A. 1997. Testing models of unthinned red pine plantations using a modified Bakuzis matrix of stand properties. Ecological Modelling 98 (1997) 35-46
Full Matrix Plots Stand Parameters against Time and Each Other by Site Quality
Full Matrix Italics identify relationships involving increment and thinning
Simplified Matrix Leary’s Triangular Form Italics indicate cells from which relationships can be derived.
Interpreting Cells • Sukachev Effect • ‘stands on good sites self-thin faster than stands on poor sites.’ • Reineke’s Rule • sd = a(dbh)b • b is approximately -1.6 • b is independent of site quality • a reflects stockability of the site
Interpreting Cells • Percent Spacing • Stands self-thin when their mean inter-tree distance approaches 10% to 20% of height. • Eichorn’s Rule • Relationship between volume and height is independent of site.
Models • SPS 4.1H • January 1999 • ORGANON • SMC Beta, April 2005.
Stand Projected • 100% DF • 400 TPA at age 15 • SI 65, 105, 145 (merchandised with the same functions)
Observations • AGE relationships make sense • Sukachev as expected • Reineke as expected • Eichorn looks good (except SI 65)
Observations • AGE relationships make sense • Sukachev as expected • Reineke shows a bit of SI effect • Eichorn looks good
Observations • Identical HT-Age • Mortality Very Different • QDBH-TOPHT differ • CVTS-Age Similar • Has value implications
Compare TPA • Observations • ORGANON -Little SI effect in Reineke • SPS 4.1 – Some SI Effect
Compare QDBH & TopHT • Observations • ORGANON taller for a given QDBH. • Expected, given denser stands.
Thoughts • Mortality model drives much of the difference between SPS and ORGANON • Both models conform reasonably well to ‘law like’ expectations. • It is interesting that CVTS is as similar as it is, given differences in TPA. • What are the value implications?