Introduction to Swamps and Tall-Herb Fens

Summary

The sampling of swamps and tall-herb fens

Swamps are species-poor vegetation types, generally dominated by bulky emergent monocotyledons, characteristic of open-water transitions with permanently or seasonally submerged substrates (Tansley 1939, Spence 1964). However, a much wider variety of communities is included here than has traditionally been encompassed by the British literature in the loosely applied term ‘reedswamp’. As for those fen communities which are also dealt with in this volume, these are vegetation types which would probably be recognised as ‘fen’ in the traditional British sense (e.g. Pallis 1911, Pearsall 1918, Tansley 1939, Ratcliffe 1977): that is, they are characterised by mixtures of certain of the important swamp emergents and a variety of often tall perennial herbaceous dicotyledons. They are commonly associated with topogenous mires but they are not restricted to openwater transitions and flood-plain systems, nor are they confined to organic substrates (Spence 1964, Wheeler 1975; c.f. Tansley 1939, Ratcliffe 1977). Furthermore, some of the communities included here as fens would probably be considered by certain authors as ‘marsh’, an expression which is best used informally as a description of any kind of wet ground and/or its vegetation.

These various vegetation types have attracted very uneven attention in Britain. Swamps can be difficult and unpleasant to work in and they reward the persistent with a dismal poverty of species. There is a wealth of information about the ecology of a very few of the important emergents, notably Phragmites australis (e.g. Haslam 1970a, b, c, 1971a, b, 1972a, b, 1973), Cladium mariscus (e.g. Godwin 1929, Godwin & Tansley 1929, Godwin & Bharucha 1932, Conway 1936a, 1938, 1942) and Glyceria maxima (e.g. Lambert 1946, 1947a, c, Buttery & Lambert 1965, Westlake 1966). Of the floristic and environmental relationships of many of the remaining swamp dominants, we know next to nothing.