Vegetation of a particularly diverse area of undrained flood-plain mire is described. Factors and processes important in determining the distribution of community-types within the study area have been investigated. Investigation of the alluvial stratigraphy has revealed the presence of a complex pattern of peat cuttings. Succession within the peat cuttings, with appropriate vegetation management, has led
to the formation of Cladium mariscus-, Phragmites communis- and Juncus subnodulosus-dominated fen vegetation and, in some areas, poor-fen communities with much Sphagnum. In areas not cut for peat, management his also sustained various rich-fen herbaceous communities(different to those of the cuttings); in its absence, fen carr develops. The differences in successional development in peat cutting areas and those not cut for peat is mainly due to difference in hydrological status.
Long term experiments established to examine effects of different
management techniques are described.
Studies of peat and peat water chemistry in a representative
selection of community-types has demonstrated local areas of
high salinity, caused by incursions of brackish water due to
exceptionally high tides and, particularly, the influence of
underlying estuarine deposits. Although large areas are flooded
by river water there is little evidence for eutrophication, except
very locally. Indeed, 'seral oligotrophication' is occurring
in isolated areas. This may preceed, but is not a pre-requisite
for, Sphagnum invasion. The most species-rich communities are
developed in non-saline areas with a fairly stable water level;
they may, however, be dependent upon flooding by river water for
maintenance of their base status.