Unit Growth

Use this variable to specify the annual unit growth (annual increment) of wood stocks on each land type. You can specify growth in either mass or volume units per unit land area (e.g m3/ha or tonne/ha). The growth values apply both to accessible and inaccessible land types.

When specifying growth for land types designated as producing wood using the Woodlot Management Practice, you will also need to specify a Growth Lifecycle Profile. This profile specifies how annual unit growth values vary over the future years of the harvest regime used by each particular management practice.

Example: Specifying Growth as a Function of Stock

You can specify static or dynamic values for growth or if you wish you can write an equation that makes the unit growth per hectare a function of the unit standing stock per hectare (in the previous year).

For example, here is an example of a function that specifies unit growth as a function of unit standing stock. It makes use of a lookup function to specify a minimum growth value when stocks are low and a maximum value when stocks are high on a land type named "Plantation". The function references the calculated result variable "Wood Stocks per Hectare" which returns a value in kg/Ha. It shows that at zero stock, the growth will be 10 kg/ha and at stocks of 200 kg/ha or higher the growth will be 20 kg/ha. At any stocks between these values, the function will use linear interpolation to calculate an intermediate growth value. For example, at a stock of 100 kg/ha, the annual growth would be 15 kg/ha. Notice the use of the PrevYearValue function, which looks up the growth as a function of the previous year's unit stock. This is required because the unit stock is a calculated value that will not be known until calculated for each scenario year.

Lookup(Linear, PrevYearValue(Plantation:Wood Stocks per Hectare[kg]), 0, 10, 200, 20)

Note: This variable is visible for the land type branches shown below relevant wood resources (under the high level Resources tree branch).