Transition mire

Transition mire can be quite variable in composition and appearance, as it is ‘transitional’ between calcareous fen and alkaline fen and can lean towards either. The habitat is typically very wet and bottle sedge (Carex rostrata) is a common and often dominant species, though other species such as marsh cinquefoil (Potentilla palustris), bogbean (Menyanthes trifoliata), cottongrass (Eriophorum angustifolium) and lesser tussock sedge (Carex dianda) can also be locally dominant. These reference states are described below.

Reference state 1 – Sedge-dominated transition mire

One of the commoner forms of transition mire is a sedge-dominated habitat typically dominated by sedges (Carex spp.), notably bottle sedge (Carex rostrata), bog mosses (Sphagnum spp.) and other bryophytes, e. g. Calliergon spp. These stands can support just a handful of sparsely distributed broad-leaved plants, such as bogbean (Menyanthes trifoliata), marsh cinquefoil (Potentilla palustris)…

Reference state 2 – Bog bean-dominated transition mire

This type of transition mire, which is visibly different to the sedge dominated form, is dominated mostly by bogbean (Menyanthes trifoliata) with sedges (Carex spp.) frequent throughout but rarely achieving dominance.

Reference state 2a – Bog bean and sedge-dominated transition mire

A common variation on the bogbean (Menyanthes trifoliata) dominated transition mires is a type where patches dominated by bogbean and patches dominated by sedges (Carex sp) co-exist side by side forming a mosaic. In the example shown here, the sedge component of the mosaic is dominated by lesser tussock sedge (Carex diandra).

Modified state 1 – Swamp encroached transition mire

This area of transition-mire, which is variably dominated by common cotton-grass (Eriophorum angustifolium), bottle sedge (Carex rostrata) and bogbean (Menyanthes trifoliata) hosts several locally scarce and rare species, such as slender cottongrass (Eriophorum gracile), bog sedge (Carex limosa) and white sedge (Carex canescens). However, the combined effects of increasing wetness, nutrient enrichment and undermanagement have…