Question: Does Stand Clumpiness have an Effect on Total Yield?

The chart below is a display of 16,669 cruised stands from multiple forest ownerships in multiple western States.  The standing cubic foot volume is charted by stand top height to remove any concern about age or site class differences.

Average volumes by top height class (60, 90, 120 and 150-feet) are summarized by clumpiness index from cruise compilations.  No growth adjustments have been made.

Stand Clumpiness

Don Monro (1973) reported: “The first philosophy assumes that the primary unit of stand modeling is the single tree and that inter-tree distance is a necessary parameter” (Distant-dependent growth models).

He also reported:  “The second philosophy assumes that the primary unit of stand modeling is the single tree, but that inter-tree distance is not a necessary parameter” (Distant-independent growth models).

Does it appear from over 16,000 stands that spatial pattern is not a necessary parameter?  Which growth model structure do you use?

Monro, Donald D.  1973.  Forest Growth Models – A Prognosis.  In: Growth Models for Tree and Stand Simulation.  IUFRO S4.01-4 Proceedings.  Edited by Joran Fries.  Pages 7 – 21.