Operable

The operable command can be used to limit when and under what stand conditions the action should be scheduled.

Actions

def MyExampleAction

Operable {simulation cycle arguments; DEFAULT = all cycles; must be >= 0}

{Conditional stand entry statements…}

See scheduling actions and activities with cycle arguments for constraining operability to specific simulation cycles. If no cycle arguments are provided following the Operable command, then the action will occur in every cycle; assuming the action is unconstrained by conditional operability statements (described below) or an action LOCK.

The commands below provide some examples of conditional operability statements. There is no limit on the number of conditions stated. If all statements evaluate as true, then the stand becomes operable and activities are scheduled. See Table below for a complete list of predefined stand measures (variables in green) that can be used to define conditional statements.

Actions

def MyExampleAction

Operable

Cycle > 2

Age >= 10

Year >= 2025

BA >= 20

GMV > 150

Variable	Metric	USA	Description
Cycle	-	-	Current simulation cycle
Year	-	-	Simulation year at beginning of current cycle
Age	-	-	Stand age in current cycle
Trees*	#/ha	#/ac	Number of trees per unit area
BA*	m^2/ha	ft^2/ac	Basal area per unit area
GTV*	m^3/ha	ft^3/ac	Gross total volume per unit area
GMV*	m^3/ha	ft^3/ac	Gross merchantable volume per unit area
RD	%	%	Relative maximum density ratio, where 1 = maximum theoretical stocking. Definition of RD and self-thinning lines (stand density index) may depend on the Variant. Consult Variant documentation. See guidance on use of RD in examples below.
QMD	cm	inches	Quadratic mean diameter
LHT	m	ft	Lorey’s height (basal area weighted average tree height)
ATV	m^3	ft^3	Average tree total volume in tree list
History	-	-	Stand management history

* Can be expressed as a ratio if a % sign follows the percentage value.

Complex operability conditions that depend on certain tree species and sized can be stated.

BA >= 20 in Spruce with DBH >= 10

Translation: 20 m²/ha of basal area must exist in spruce trees with DBH >= 10 cm.

BA >= 20% in Spruce with HT >= 10

Translation: 20% or more of total stand basal area must be in spruce trees with height >= 10 m.

RD >= 70%

Translation: stand must have >= 70% relative density (current density index / maximum density index).

Note: IN and WITH conditions cannot be used with RD in operability statements, but can be used in retention statements

History = “CT”

Translation: stand must have previously had a treatment where stand history was updated to “CT”.

See conditional statement documentation regarding formulation of IN and WITH conditions.