Accessibility Fraction

See also: Analysis View, Land-based Resource Calculations, Setting Up a Land-based Resource Assessment

The fraction of the area of a particular land-type that is accessible to being harvested (expressed as a percentage value).  Inaccessible areas will not have their wood stocks cut even if demand exceeds supply.  This variable is only relevant for land-types that produce wood and which are marked with the OtherForestry Management Practice.

The accessibility fraction is set for the base year of a study and is assumed to be constant.  The variable is not visible in scenarios. Note however that the total land area accessible in each region/land type may change over time due to land-use change.

Several factors may make wood inaccessible and thus keep the accessibility fraction below 100%.  First, wood resources may be far from demand centers or transport routes.  Second, legal or tenurial constraints may restrict access to land (e.g., parks and reserves or protected private farmlands whose wood resources are held off the market).  Finally, harvesting tools may be inadequate to utilize whole trees. Typically, trees on agricultural land will have an accessibility close to 100%, while remote forest or bush areas would have a lower accessibility.

You may wish to make separate estimates of these three factors - referred to as the location access fraction (Al), the tenure access fraction (At) and the management access fraction (Am) respectively.

The overall access fraction (A) is calculated as

A    =    Al x At x Am

It is important to remember that these terms must be calculated sequentially.  That is, At is a fraction of Al and Am is a fraction of Al x At.

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