This section describes how the areas of suitable habitats are calculated.

 

 

flag_green        Partial set aside are not included

Note that nature partial set aside areas created during a simulation are currently not included when running a habitat model since they have no GIS-representation.

 

 

tog_minusAlgorithm for raster-based models

The following is made for each period (and model):

1.The criteria for habitat score 1 is evaluated for each stand polygon. A stand that meets these requirements is temporarily assigned value one.
2.The criteria for habitat score 0.5 is evaluated for each stand polygon that does meet the criteria in step 1. A stand that meets these requirements is temporarily assigned value 0.5.
3.The polygon layer is converted to a raster layer where a raster cell is assigned a value of 0, 0.5, or 1 depending on which polygon it is located within (the cell center) and the outcome from step 1 and 2.
4.If the current habitat model includes adjustment for interior edge, the values assigned in step 3 are adjusted for cells that are affected by the edge*.
5.The habitat area within a given neighborhood (radius) of each cell is calculated. The neighborhood is defined by the circle that corresponds to the  neighborhood radius defined for the habitat model.
6.For each grid cell that meets the neighborhood criteria, the value from step 3 is saved. The value for a raster cell that does no meet the neighborhood criteria is set to 0.
7.For each polygon, the sum of the values from step 6 for the contained cells are calculated each polygon. The sum is then divided by the sum of the cell areas. This ratio is finally multiplied with the stand's productive area. This is done to avoid problems with that a polygon area may differ from the productive area, Heureka only considers the productive area.

 

*Interior edge zone may occur when an older stand is adjacent to for example a pasture field, a lake, or a young forest plantation..

 

<%EXTOGGLE%>Algorithm for vector-based models

 

The following is made for each period (and model):

1.The criteria for habitat score 1 is evaluated for each stand polygon. A stand that meets these requirements is temporarily assigned value one.
2.The criteria for habitat score 1 is evaluated for each stand polygon that does meet the criteria in step 1. A stand that meets these requirements is temporarily assigned value 0.5.
3.For each polygon a neighborhood is calculated. This neighborhood consists of other stand polygons that intersect a circle whose center corresponds to the subject polygon's centroid. For each intersecting polygon, the area within the circle is also calculated.
4.For each stand polygon, the area that meets the neighborhood criteria is calculated.
5.For a stand with a qualified neighborhood, the area of suitable habitat is set equal to what was calculated in steps 1 and 2. Otherwise this area is set to zero.

 

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