7.9.6. Zonal statistics of land cover values within buffers

The newly created raster images contain zones with the value 1 (where the Raster calculator expression was true) and 0, where the expression was false. This binary classification can now be used to calculate the percentage of each land cover class within any polygon layer, e.g. the honey bee colony buffers (also see section 6.9.7.):

  1. Open the menu Raster > Zonal statistics > Zonal statistics.
  2. Choose one of the newly created binary raster images (e.g. CLC06_class211.tif) as input Raster layer.
  3. Select bees_colony_locations_buffer.shp as input Polygon layer containing the zones.
  4. Choose an appropriate column prefix (e.g. the land cover class “211”) and Click OK.
  5. Repeat steps 38 to 41 for the other input rasters (choosing appropriate filenames for the results, see Fig. 114).

Opening the attribute table of the layer bees_colony_locations_buffer.shp, you see new fields at the end: The field “211mean” represents the average percentage of the land cover category “non-irrigated arable land” within the respective buffer (honey bee colony).

Fig. 114. Performing zonal statistics from raster values based on a polygon vector layer.