Action: From time to time it is useful to have MGM "watch" for changes in the state of the stand. Stand characteristics such as density, basal area, site index and so on may be monitored. An experimental facility exists for setting up "watch expressions" on a few selected characteristics. A watch expression specifies a stand characteristic and a numerical criterion, e.g. "Density < 2.5". (Some characteristics like site index are species-specific.)
During the execution of a crop plan, any event that is capable of changing stand characteristics (establish, grow, thin, etc.) is followed by an evaluation of all current watch expressions. If any expression is satisfied, a message is recorded in the Messages sheet and execution may continue or terminate or execution of events in the current crop plan may be skipped.
The action to be taken is specified by the user in the form of "WarnIf", "StopIf" or "SkipIf" events inserted at the beginning of the crop plan. Watch expressions remain in effect until cleared (by the "Clear Watch" event.) To insert a watch event, you click on the "Watch" selection and then choose from the four radio-button options (Clear Watch, WarnIf, StopIf or SkipIf) and then create the watch expression.
The monitoring facility is under development and will be modified as experience is gained. Feedback is requested.