The quadrat locations were measured with a geodetic differential GPS receiver at 2–4 cm accuracy. For each quadrat centre a circular 1 m buffer was generated to summarise the terrain characteristics, based on the DSM and its derivatives, in the direct neighbourhood of the quadrat. These buffers were used to account for the topographic variation and sub-surface water availability in the direct vicinity of the 25 cm by 25 cm quadrats. Zonal statistics were then used to calculate the average contributing area for each quadrat, so that the relative water availability based on the DSM could be related to the moss health and water content measurements in the field.