Botanical diversity in British mires

Abstract

Although mires are sometimes regarded as a single, specific and even esoteric habitat-type, in their full range of development -calcareous fens to acidic bogs, lowland swamps to upland flushes, woodlands, sedgelands and mosslands -they occupy a wide range of environmental conditions and sustain a rich botanical resource. Here an outline is given of the types of mires that are widespread in Britain and their botanical resource. It is discussed with reference to some of the environmental variables and management conditions that have been shown to influence the species composition and diversity of their vegetation. Some implications that this has for the classification of mires are outlined.

Bryophytes and lichens in peatlands and <em>Tepualia stipularis</em> swamp forests of Isla Grande de Chiloé (Chile)

“…After comparing the floristic results obtained here with results already published for ombrotrophic peatlands in the Northern Hemisphere, the low number of Sphagnum species in the studied area stands out: only six, a number much lower than that established for Canada (Vitt & Belland, 1995) or Great Britain (Wheeler, 1993). It is important to note that in Chile no taxonomical review of the genus Sphagnum has been carried out, so the number of reported species could vary after further studies.…”

“…The vertical gradient, which translates into a microtopographic or microstructural division, embraces from pools and water saturated depressions to dry hummocks. This is one of the most relevant factors when assessing the specific richness and the floristic composition (Andrus & al., 1983;Wheeler, 1993;Wheeler & Proctor, 2000;Rydin & Jeglum, 2006). The latter is not applicable to tepuales, where the bryophytic carpet is homogeneous.…”

“…Europe and North America have completed inventories of peatland floras (Malmer, 1962;Vitt & Belland, 1995;Wheeler, 1993), and this has permitted them, among other things, to determine the species that indicate the type of peatland, to study their ecological niches and to assess its relations with environmental parameters (Vitt & al., 1975Gignac & Vitt, 1990;Gignac & al., 1991). Unfortunately, this is not the situation in southern cone South America.…”

“…For instance, Vitt & Belland (1995) reported 20 species of liverworts in Canadian peatlands, and Wheeler (1993) pointed out 17 species of liverworts in British bogs. The specific richness of both is significantly surpassed by the 30 taxa found in Chiloé.…”

Peatlands as scientific archives of past biodiversity

“…They are distinguished from the other main type of peatland, the minerotrophic or 'rock-fed' sorts, which occur in valleys and basins, or on river floodplains and are nourished by inflowing streams as well as by precipitation. The sub-division of the various types of mires that make up peatlands in the broad sense are dealt with by Wheeler (1993). Minerotrophic peatlands are subject to many influences by way of both natural and cultural changes in the catchment and their 'archive', while still valuable in many ways (Brown and Barber, 1985), gives a composite picture rather than the clear signal of atmospheric input only that pertains in raised bogs.…”