Biology Fieldwork

A Level

Qualitative methods

Using a gridded quadrat to sample vegetation

3. Qualitative methods

Species lists

The simplest data that you can collect is a species list. This is a record of the names of each plant species that is present. lt is also known as presence /absence data.

A species list provides no information about how abundant each species is. For example, a foredune ridge might be almost wholly covered in clumps of marram grass, with a few individual sea holly plants. But the species list would only record the presence of the two species.

ACFOR scale

The ACFOR scale can be used to collect data on the abundance of each species

  • Abundant
  • Common
  • Frequent
  • Occasional
  • Rare
  • None

If you are comparing more than one site, some plants could be totally absent in some samples, so can be recorded as N for NONE.

Data collected on the ACFOR scale is often biased or subjective. Many investigators over-estimate conspicuous plants (especially those in flower) and under-estimate inconspicuous plants. More reliable data will come from quantitative methods.