Permanent non-tidal, fast, turbulent watercourse of plains and montane regions with Ranunculus spp.

The habitat includes river stretches with a stony, gravelly or shingly river bed with an average flow velocity over 0.2 m/sec. Main physical differences between this habitat type and C2.3 (Permanent non-tidal, smooth-flowing watercourses) are the higher flow velocity and the bigger grain size of the sediments. These two habitats, as well as the  habitat C2.2a (Permanent non-tidal, fast, turbulent watercourses of montane to alpine regions with moss communities) may be related as segments of the same stream or river. These stretches of rivers are usually natural and unaltered. The natural hydrological regime is variable, alternating periods of low water level (but never completely dry) and floods. This regime promotes a cyclic development of the vegetation, the coexistence of various microhabitats, the self-purification due to the high oxygen level. This habitat is characterized by patches of stone beds devoid of any plant species, patches of aquatic mosses attached to stones and patches of submerged rooting macrophytes. Characteristic submerged macrophytes are Potamogeton alpinus, P. polygonifolius, Ranunculus fluitans, and Callitriche hamulata. Also Potamogeton pectinatus occurs in this habitat with long and narrow leaves floating in the water stream, but might be considered as a species that characterizes less optimal circumstances. Once the water become deepand slowly flowing, Nuphar lutea and other species of the genus Potamogeton become more characteristic. Emergent amphibian plants such as Berula erecta, Apium nodiflorum, Hippuris vulgaris, Butomus umbellatus, Schoenoplectus lacustris, Sagittaria sagittifolia and Sparganium emersum can also develop in more shallow and illuminated parts of this habitat. Due to the strong current these emergent plants usually develop in this habitat their submerged growth forms with leaves adapted to the water movement. Usually, vegetation cover of the habitat does not exceed 30% of the total area of a river stretch. The vegetation can include also species with a wide abiotic range such as Groenlandia densa, Zannichellia palustris, Myriophyllum spicatum, Nuphar lutea. Species variation is dependent on flow velocity, water depth, sediment type, shading and nutrient richness. Surface water is speedily flowing and rich in oxygen. These are important favorable circumstances for benthonic macroinvertebrates and fish communities.

Indicators of good quality:

• Flow velocity exceeds 0.2 m/sec
• Riverbed is mainly stony, pebbly or gravelly, with few finer sediments (sand)
• No accumulation of fine (silt and clay) and organic sediments
• Hydrological regime is natural as well as morphology is unaltered
• No or limited occurrence of exotic species
• Limited development of emergent species
• No or limited formation of floating mats of organic residuals.

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats