Spatially balanced sample for the whole of Flanders based on the Generalized Random-Tessellation Stratified (GRTS) method (Stevens and Olsen, 2004). The sample consists of a grid of 32 meter x 32 meter cells, each having a unique ranking number. This so-called master sample is used as a basis to draw samples for different Natura 2000 habitat types in Flanders. A sample with sample size n for a certain habitat type is selected as follows: (1) select all grid cells of the master sample that overlap with the sampling frame of the target habitat type and (2) select the n grid cells with the lowest ranking number. Reference Stevens, D. L. and Olsen, A. R. (2004). Spatially-balanced sampling of natural resources. Journal of American Statistical Association, 99: 262-278.