The sampling of mire vegetation

In our survey of mires, the primary purpose has been to provide a classification of their vegetation according to its floristic composition, and not to categorise mires on the basis of their ecological development or hydrology, their situation in the landscape, or their gross morphology or fine surface patterning. Each of these other approaches to describing mires can yield benefits of its own, and we have tried to bring their various perspectives to bear in the interpretation of our results. Indeed, it was our hope that we might achieve some greater measure of understanding as to how the vegetation of mires relates to their form and function as perceived from these different standpoints. In the task of data collection, however, we were not concerned to dispose our samples according to any prior judgements about what did or did not constitute a particular kind of mire environment; rather, to ensure an adequate representation somewhere in our scheme of all vegetation types found in and around mires.

Most of that vegetation is described in this section of the work. Essentially, we are dealing here with communities made up of bryophytes, herbaceous plants and sub-shrubs sampled from a wide variety of bogs and wet heaths, fens, flushes, springs and soakways, where the ground is kept permanently or periodically waterlogged by high atmospheric humidity, a high ground watertable or lateral water flow. Many of the vegetation types occur on soils that are organic in character, but some are characteristic of mineral profiles, and the account presented here is thus not simply a classification of samples from peatlands, a category that is sometimes taken as synonymous with mires. On the other hand, there are certain kinds of vegetation which are often encountered in these different sorts of mires, indeed which frequently form an integral part of their mosaic of communities, but which are not included here. We did sample these, applying the same general principles of data collection throughout, but allowed the floristic distinctions among the vegetation types to emerge in the analyses, and have described certain communities in other sections of the work. Sometimes the reasons for this are more obvious, as with the various kinds of woodland that are associated with mires.