Setting up a patch criteria account

A prerequisite to setting up a patch account is to define a patch membership criteria account. Multiple patch size class accounts can then be defined, each refering to the same criteria account.

The first step is to set up an account that describes the patch membership criteria. In our example this account will contain the disturbance attribute. The following lines should be included in the accounts.csv file in order to define this account(for more details about summary accounts see the section called “Summary Accounts”).

GROUP,ATTRIBUTE,ACCOUNT,SUM
_ALL_,feature.Visual.disturb,patch.disturbance.young,1
...
      

The attribute that is being used as the patching criteria is feature.Visual.disturb. The value of this attribute is described in Figure 36, “Patch criteria attribute”. This account will sum disturbance over the landscape. If we were to stop here before defining patch accounts, this account would only sum the total disturbance over the entire forest with no regard for various patch sizes or shape. However, if we use this account as input to a patching account, it will serve the additional purpose of helping to indicate which blocks are candidates to join patches.

[Tip]Tip

More than one type of patch can be defined simultaneously (e.g. disturbance and old growth). Other patch accounts can be defined by creating additional patch criteria accounts in the accounts.csv file, with a different stand attribute or the same attribute but different geographical group. This may be useful if the planning area has been divided into a number of sub-areas, for example North and South each having different patch size or criteria policies.

GROUP,ATTRIBUTE,ACCOUNT,SUM
north,feature.Visual.disturb,patch.disturbance.north,1
south,feature.Visual.disturb,pathc.disturbance.south,1
      

The above two patch criteria accounts use the same attribute to keep track of disturbances over different geographical zones. Patch accounts could be defined for both in the PIN file. Each zone of the landscape could have independent targets to represent the landscape pattern objectives.

In a slightly different example, multiple attributes could contribute to create the patch criteria. For example, we might have different conifer and hardwood greenup timings.

GROUP,ATTRIBUTE,ACCOUNT,SUM
_ALL_,feature.greenup.conif,patch.greenup,1
_ALL_,feature.greenup.decid,patch.greenup,1
      

In this case, we would need to be careful that the values for the greenup attributes are defined correctly and do not overlap (i.e. each track has only conifer or deciduous greenup, but not both).

Now that we have defined a patch criteria account, we can break the disturbances down into patch size categories. Create categories for various patch sizes to get a better understanding of the distribution pattern of disturbance over the landscape. See the section called “Creating patch account definitions using the PIN Builder” for step by step instructions to define patch accounts using the PIN Builder and creating appropriate patch size classes. Read on to better understand the patch sub accounts that will be created and available in the model.