This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
A heath presents a more or less uniform type of formation. There is no zonation, save at the periphery of a region of wood (or scrub), and except where it is wooded it presents a series of dominant associations or societies, which can be studied on a broad basis, and mapped as in the case of moors and bogs. Apart from the lines formed by the extent of the Ling, Heaths, Furze, Broom, Whortleberry, etc, there are the lesser societies that endeavour in more open spots to maintain an existence. These should be carefully studied, as in the case of meadows and pastures, by staking out squares, and the plants counted, or put down on squared paper. The dominant plants in these cases should be noted, and their percentage estimated.
Where there is woodland, this should be studied as in the case of woods (Section IV). The influence of the tree growth on the heath types should be noted, as also the form of the wood or the alternation of wood and heath.
The openness and extensiveness of a heath makes it especially adapted to the study of the plants from the ecological point of view; for there are no barriers, and a base line for the squares to be studied can be laid down almost anywhere.
The particular conditions of soil, the effect of light, wind, etc., should all be studied in relation to the adaptations of the plants to meet the special conditions in each case. Advanced students may make pot cultures, make observations on the rainfall or light intensity, water-content, etc.