The DAFOR scale is used for semi-quantitative sampling, to provide a quick estimate of the relative abundance of species (generally plants) in a given area. Abundance (number of individuals) and cover (area coverage) are often used interchangeably in this type of surveying, although in fact they may have very different meanings.
To obtain useful abundance data the areas being surveyed are divided into sections (usually squares) of equal size. The entire area is surveyed for species, and categories assigned according to percentage cover.
The DAFOR scale comprises following categories:
| Value | Percentage cover | Notes |
|---|---|---|
| D - Dominant | > 75% | Rarely used in practice. |
| A - Abundant | 51 - 75% | Very common over most of the site |
| F - Frequent | 26 - 50% | |
| O - Occasional | 11 - 25% | |
| R - Rare | 1 - 10% |
It is generally recognised that recording plant cover using the DAFOR scale is extremely subjective, being affected by a number of factors and in particular recorder bias.
1. If a species appears to be intermediate between two categories, it is generally assigned to the lower category.
2. In some implementations the prefix 'L' is used where species are local (ie. distributed in a patchy manner) - for example, LF (locally frequent).
However this significantly complicates interpretation of the results, and is generally discouraged.
3. Occasionally alternative implementations of the DAFOR scale are used - for example: