Setting Targets for Visual Quality

We return now to our original planning objectives of addressing both the visual quality objectives while maintaining a sustainable wood supply. When we were examining the table we noticed that our block belongs to the 1-MI2 VQO. Let's take a look at these areas in the Map Viewer.

  1. In the Legend Panel of the Map Viewer uncheck the box next to the Seral Stages layer. The seral stage colours will disappear.

  2. Check the box next to the layer entitled VQO Areas. This will turn on this map layer. This map layer is derived from the same file as the Seral Stages layer, however a different attribute has been used to classify and display information. This layer is based on the VISUAL attribute we examined earlier.

Now we can see that this VQO area is composed of a group of polygons. Be sure to leave our block selected so you can zoom back to the selected polygon again.

  1. Zoom to the Full Extent to see where all VQO areas are located.

To regulate the amount of disturbance that is visible at any particular time we need to know the total area of each VQO zone and what percentage of that area appears visually disturbed. Since a VQO consists of a group of polygons, each with their own attributes and characteristics, we need to sum attributes from each block in the group to create an overall account for the VQO.


Accounts sum attribute values from groups of polygons (often all polygons in the forest). We can track cumulative effects over large geographic areas and over the entire planning horizon by summing individual block attributes into accounts. We can establish targets on these accounts that will cue the scheduler to make allocations in a way that will achieve our overall management goals for the forest (see the section called “Dynamic Stand Attributes” and the section called “Accounts”).

In our VQO example, we are classifying visual disturbance of stands that are less than 30 years of age. In our data preparation step we created a stand-level attribute for visual disturbance that is based on this classification. When we created the VQO accounts we indicated to the Patchworks model to add the area of any block that is 'disturbed' to the appropriate VQO account. Let's look at a few accounts, and see how they related to the management targets.

  1. At the bottom of the map legend there are four control panel tabs named Legend, Targets, Reports, Comparisons. Choose the Targets tab. The Targets control panel should appear.

  1. The accounts are organized in a tree-like hierarchy. To find the 1-MI2 VQO account, expand Feature > VQO and scroll down the list until you see 1-MI2. Click on 1-MI2 to open the Target Chart for this account (Figure 9, “The Target Chart control panel.”).

The "target chart" that is displayed is a histogram composed of 41 bars to represent all 40 periods plus one to express the initial conditions. Accounts can have minimum and/or a maximum target levels set to give the model direction with respect to planning goals. If the account is turned on (active) the model will take the targets into consideration when it is making its allocations. If the account is not turned on (inactive) the scheduler will not take the targets into consideration, but will still track the values as an indicator.


A target chart displays the targets set for a particular account for each period of the planning horizon. See the section called “Target Charts” for a complete explanation.

Figure 9. The Target Chart control panel.

The target chart for VQO 1-MI2 shows that a maximum target of 115.156 ha of visually disturbed area is set for all planning periods (blue bars).

Our VQO goal is that disturbed forest should not exceed 20% of the total forest area of the VQO. We can calculate appropriate number of hectares to meet this goal in Patchworks.

  1. First bring up the block attribute table again and click on the Unselect all records in the selection button.

  2. We will then calculate twenty percent of the total area of each of the VQO areas. Click on the Summarize data values button. This will bring up a dialog box having two fields allowing entry of category and value. In the dialog box, click on each Expression Builder icon and then use the tool to enter VISUAL as the category and TOTALAREA*0.20 as the value. Alternatively, you can just type the expression in entirely using the keyboard.

The Summarize Table Values wizard will will compute values by each category.

  1. Upon clicking on Finish you will see a Summary values table containing the resulting calculation for each of the eight VQO areas. You will see that twenty percent of the 1-MI2 area is 115.157 ha. This will be the maximum target value for this account.

The results of the Summarize Table Values tool are displayed in a Table Viewer window, with one row for each unique category. As with any table, the results can be sorted, selected, refomatted, exported and joined with other tables.

  1. Along the bottom of the target chart there are 3 coloured boxes that represent data values for the period of interest. The red box displays the minimum target value, the grey box displays the current target achievement value, the blue box displays the maximum target value. The values in these boxes will change depending on the period that the mouse pointing at most recently. The blue box contains 115.157, representing our 20% maximum in this VQO area.

  2. For our target to be considered by the scheduler both the target level and the account itself must be active. The first three icons on the left are used to activate the account and target. Grey activates the target itself, red activates the minimum target level and blue activates the maximum. A indicates inactive whereas a indicates active. Be sure there is a grey to indicate the target itself is active, as well as a blue to indicate that the maximum target level is active. The minimum target level should remain inactive.

As you can see from the targets control panel, quite a few accounts are available in this model. By default, all targets are inactive, and thus only track the condition of the forest. We must change the targets to active, if we want to have a target participate in the objective function. The schedulers algorithm in Patchworks attempts to achieve a spatially explicit solution that balances all the objectives defined in the active accounts while making its allocations. Let us explore this concept by adding an additional target to harvest a sustainable volume throughout the time horizon.

  1. Find the conifer harvest account in the targets control panel under the product > Yield > managed > Conif target (Figure 10, “The conifer harvest account.”). This account sums the total amount of conifer volume harvested from each block in the entire forest. We will use this account to set a minimum harvest level at 598,000 m3 per period (notice the minimum target value in the lower left hand corner). See Figure 59, “Quick Tour of a Target Chart ” for more information on interactive target adjustments.

Figure 10. The conifer harvest account.

The conifer harvest is set at a minimum of 598,000 m3 per period (or 119,600 m3/year).

  1. Be sure the minimum target level is active with a red .

  2. Be sure the entire target is active with a grey .