Standardized map of habitat types and regionally important biotopes in Flanders

The  habitatmap_stdized.gpkg file is a processed version of the Natura 2000 habitat map of Flanders (De Saeger et al., 2023; see also De Saeger et al. 2017). It contains all polygons with Natura 2000 habitat types or regional important biotopes (RIB). This file is used as a basis for designing monitoring schemes in Flanders.   

In the original habitat map, every polygon can consist of maximum 5 different types (habitat (sub)types and regionally important biotopes). This information is stored in the columns  HAB1, HAB2,..., HAB5 of the attribute table. The fraction of each type within the polygons is stored in the columns PHAB1, PHAB2, ..., PHAB5.

The habitatmap_stdized.gpkg file is a GeoPackage that contains:

• habitatmap_polygons: a spatial layer with every habitat map polygon that contains a Natura 2000 habitat or RIB type.
• habitatmap_types: a table with information on the habitat and RIB types (HAB1, HAB2,..., HAB5) that occur within each polygon of habitatmap_polygons.

The processing of the habitatmap_types table included following adjustments:

• For some polygons the type is uncertain, and the type code in the raw habitatmap data source consists of 2 or 3 possible types, separated with a ','. The different possible types are split up and one row is created for each of them, with phab for each new row simply set to the original value of phab. The variable certain will be FALSE if the original type code consists of 2 or 3 possible types, and TRUE if only one type is provided.
• Some polygons contain both a standing water habitat type and rbbmr:
  • 3130_rbbmr,
  • 3140_rbbmr,
  • 3150_rbbmr, and
  • 3160_rbbmr.
• Since habitatmap_stdized_2020_v1, the two types 31xx and rbbmr are split up and one row is created for each of them, with phab for each new row simply set to the original value of phab. The variable certain in this case will be TRUE for both types.
• After those steps, a given polygon could contain the same type with the same value for certain repeated several times, e.g. when 31xx_rbbmr is present with phab = yy% and 31xx is present with phab = zz%. In that case the rows with the same polygon_id, type and certain were gathered into one row and the respective phab values were added up.

The R-code for creating the habitatmap_stdized data source can be found in the GitHub repository 'n2khab-preprocessing' at commit abf596e.

A reading function to return the data source in a standardized way into the R environment is provided by the R-package n2khab.

Attributes of habitatmap_polygons:

• polygon_id
• description_orig: polygon description based on the original type codes in the raw habitatmap 

Attributes of habitatmap_types:

• polygon_id
• type: the interpreted habitat or RIB type
• certain: TRUE when type is certain and FALSE when type is uncertain
• code_orig: original type code in raw habitatmap
• phab: proportion of polygon covered by type, as a percentage.

Since version habitatmap_stdized_2020_v1, rows are unique only by the combination of the polygon_id, type and certain columns.