Blocks

The term "block" is often used in many different ways, but in Patchworks it has a very specific meaning. In Patchworks parlance a block is:

Before being used by Patchworks, the original inventory is usually overlayed with buffers, wildlife areas, and other areas of concern; many smaller sliver polygons are created. We refer to these tiny areas as fragments (in some jurisdictions they are known as resultants). It would be unrealistic to consider allocating management treatments on these small slivers, and a common data preparation step is to aggregate or group polygons together into candidate blocks (see Figure 19, “Creating blocks from the inventory”). In the grouping process the objective is to form block that are of a size, shape and composition that make sense to operational planners as realistic units of allocation (see the section called “Using the Group Fragments Tool”.

Figure 19. Creating blocks from the inventory

The original inventory overlayed with areas of concern (resulting in a large number of fragments) is simplified into a "blocks" layer by grouping similar adjacent fragments according to operational criteria. The result of grouping tends to be a substantial reduction in dataset complexity with no loss of aspatial accuracy. If done properly all aspatial summaries will be the same before and after grouping.


On the other hand, overly large polygons may exist that is also unrealistic for allocation. These polygons should be split into smaller pieces for use by the scheduler (see Polygon Splitter).

Regardless of how the initial dataset is prepared, the candidate harvest blocks have treatments allocated individually and atomically. The scheduling model may choose to allocate treatments to a number of adjacent candidate blocks in order to create larger openings, but candidate blocks cannot be split in to smaller pieces.

Grouping can also be used to track the development of managed (i.e. available for harvest) and unmanaged (i.e. reserved forest) within a single candidate block shape. The Patchworks model can maintain separate area, age and attribute forecasts for managed and unmanaged areas within blocks, allowing for the simple and convenient expression of within stand features such as retained areas, riparian buffers or other features that smaller than the resolution of the inventory (see Figure 20, “Unmanaged and managed portions within blocks”).

Figure 20. Unmanaged and managed portions within blocks

The unmanaged 3 ha portion within the above block is tracked separately from the 10 ha managed component, and aspatially within the 13 ha block. Patchworks will track that the area is located somewhere within the polygon, although at this level of analysis the exact location is not important. If the exact location was important (i.e. for connectivity analysis) the fragments should not be grouped together.