Unvegetated or sparsely vegetated shore with mobile sediments in the Mediterranean region

This habitat includes silt, sandy and gravel banks and shores of flowing and standing water bodies of the Mediterranean areas. The rivers can be intermittently flowing (completely dry during the summer or left with some pools) or constantly flowing but with abundant exposed sandy or gravel sediments exposed during the summer. This category includes Mediterranean lake-bottoms or edges with mobile sediments (silt, sand or gravel) temporarily exposed by fluctuations of the water level, wind or wave action.

In the Mediterranean region, the climatic conditions are characterized by annual precipitation patterns that are high during autumn and winter but low during summer. Thus, many streams have developed spatial and temporal discontinuities of flow regime. Flow is interrupted during the summer dry period, but even energetic flow is observed during the wet season from late autumn to early spring. During the wet season, high precipitation lead to floods and consequent disturbances, such as sediment disturbances or even changes in the morphology of the stream channel. These seasonal differences in hydrological condition imply the need for specially adapted taxa to persist in this habitat. At the same time this habitat can host many plant species that require different moisture conditions (from humid to very dry). The high evaporation rate on certain geological substrates during summer can cause the accumulation of salts and oxides, therefore also species tolerant to brackish soil can occur. In some cases the geological substrate is very rich in salt and salt crusts are formed with the drying of the riverbed. In this specific case the dominant vegetation is tolerant to high salt concentrations and the habitat belong to the types C1.5 (Permanent inland saline and brackish waters) and C3.5c (Periodically exposed saline shores with pioneer and ephemeral vegetation). Despite the similarities with temporary running waters in temperate regions, there are differences in the timing and dynamics of nutrient inputs.

The grain size of sediments depends by the water regime and the history of water bodies both in flowing and standing waters and influence the plant species composition of the communities occupying this habitat type. These areas could be either completely unvegetated or occupied by vascular plant communities including pioneer vegetation and subsequent early stages of colonization. Often these areas are neighbouring with riverine forests and scrub of Salix spp., Populus spp., Tamarix spp., Nerium oleander and Vitex agnus-castus.

Indicators of quality:

• Natural hydrology
• Suitable geological substrate (easily erodible)
• Pioneer vegetation with absence or sporadic abundance of nitrophilous species
• No communities of exotic invasive species
• No negative anthropogenic influence (sediment extraction, regulation of the water regime, construction of artificial banks)

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats