NET AERIAL PRODUCTION BY CALLUNA VULGARIS ON LOWLAND HEATH IN BRITAIN

Different aspects of the ecology of Calluna vulgaris* and the communities in which it is found have been of interest to many workers and are reviewed by Beijerinck (1940) and Gimingham (1960, 1972). Calluna occurs over much of Europe in a range of communities where it may be present in varying abundance. In Britain the plant is found from sea level to just over 1000 m and is often the dominant plant on heath and moorland areas with few associated species. As Calluna becomes dominant where the supply of available plant nutrients is low it is important to consider the overall nutrient budget of heathland and to establish and quantify the amounts of nutrients contained in the particular components of the ecosystem. In recent years a number of studies have looked at the rates of growth and the nutrient budgets of heathland and moorland areas (Robertson & Davies 1965; Bellamy & Holland 1966; Chapman 1967, 1970; Forrest 1971). With the advent of the International Biological Programme a number of Calluna sites have been examined in considerable detail, both botanically and zoologically. In nearly all such studies the measurement of some component of primary production, or the standing crop, is needed as a basis for the study of other features such as the nutrient budget, litter production, decomposition, secondary production or grazing. This present account describes the net aerial production by C. vulgaris and associated plant species growing on an area of lowland heathland in southern Britain. It is hoped that the data are presented in such a way that comparisons can be made with Calluna growing under different climatic or geographical conditions; for this reason the results are detailed in an appendix as well as being presented in graphical form. The measurement of root production poses many problems and is generally less well studied than aerial production. The work described here is no exception and concentrates upon above ground production. It is impossible to make full and valid comparisons with other sites and types of vegetation without considering root production; preliminary but less satisfactory estimates of root production have been made (Chapman & Webb 1975) and will be published in more detail later.