Non-Declining Yield


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Non-Declining Yield Constraints

Non-declining yield (NDY) constraints are usually applied to a model to ensure that over-cutting of particular resources does not occur. Such that no less yield is harvested in any period compared to any previous period.

While they are most commonly applied to the total clearfell volume, NDY constraints can also be used to ensure that Area harvested, Net Cashflow, Revenues or Costs are non-declining in the model.

The non-declining yield constraint window is shown below.

Period Range

This option specifies what periods the constraint is to apply. Checking the box All will mean that the constraint will apply for all periods. Alternatively, a period range can be entered by entering the first and last periods in the two boxes below.

Croptype Range

Depending on what is selected in the Category field, a range of croptypes or attribute names will be available in the Croptype Range list. Using the mouse, highlight the desired croptype ranges for which the current clearfell specification is to apply. To select consecutive items in the list, click the first item, press and hold down the [SHIFT] key and click the last item. To select non-consecutive items, press and hold [CTRL] and click each item.

Age Range

The age range defines the range of age classes for which the particular constraint will apply.

To specify all age classes, simply ensure that the All Ages box is checked. Note that LOG will check this box automatically.

To specify a range of age classes, ensure that the All Ages box is not checked and enter the first and last age classes in the boxes provided below.


Selects whether yield, area, revenue or cost is non declining.

Error Checks*

The latest version of LOG now includes error checks on all inputs. This means that all fields need to have appropriate entries before the addition to the model is added. If there is something missing, or something in the wrong form, then a message is shown that prompts the user to remedy the situation.