Base-poor spring and spring brook

Springs are habitats where groundwater discharges to earth surface or to a water body. Their microclimate, hydrology, water volume, chemistry and discharge type (rheocrene, limnocrene, and helocrene springs), and consequently animal and plant communities, are very variable. Sometimes springs are dominated by abiotic features, sometimes their biotic communities are very rich (particularly helochrenes with moss carpets, specialized plants and macroinvertebrates). Springs are usually small-sized but in some cases large complexes (up to several hectares) of pools, vegetation patches and moist seepage areas occur. As compared to other moist habitats spring habitats are characterized by low temperature, small annual fluctuation in the water temperature, and often by high content of oxygen in the water. These features are most representative in cold stenothermic springs where mean temperature is only a few degrees above 0⁰C and the annual amplitude is very small. The pH of base-poor springs is typically from slightly acid, form pH > 5.5 to circumneutral or slightly alkaline. The diverse physical structure and the water chemistry are main determinants for spring biota, the former particularly to macroinvertebrates, the latter to bryophytes. Through groundwater, rich in nutrients and oxygen, springs have often locally enriching influence to adjacent habitats, for example to headwater streams or to mire, meadow or forest habitats. On the other hand, adjacent habitats, for example forest, can have strong influence on springs and spring brooks, both by shadowing and as a source of allochthonous material. The stenothermic springs in cold (arctic, alpine) areas are dominated by mosses, while cover of vascular plants (such as Saxifraga spp., Koenigia islandica, Epilobium hornemanni) is low or zero. In montane and subalpine springs vascular plants, representing alpine and arctic floristic elements, are more common, but in most cases moss communities prevail. In lowland springs vascular plants can be abundant. Due to their characteristic microclimate, with a low temperature during the growing season, springs can accommodate disjunct (often relict) occurrences of northern and alpine species. However, in northern locations, they can maintain also occurrences of species with southern origin, due to unfrozen water and soil during wintertime. Spring habitats are sensitive to disturbances, because they are affected by changes in their close surroundings but also in their catchment areas. Many springs have been destroyed or deteriorated in quality due to a range of activities related to groundwater abstraction, utilisation of spring brooks, forestry, clearing of agricultural land, soil and rock excavation, and construction activities. Threats include eutrophication and chemical contamination too. In arctic, alpine and north boreal areas spring habitats have remained to large extent in natural condition, in lowlands many of them have been destroyed or their quality declined.

Indicators of good quality:

• Natural hydrology and water chemistry in springs and spring brooks,
• Low anthropogenic influence (drainage, water exploitation, forestry, agriculture, eutrophication etc.) in springs, their surroundings and catchment areas,
• Presence of plants and animals adapted to spring conditions, including threatened species,
• High cover of mosses and specialized vascular plants,
• Rich macro-invertebrate fauna,
• Low cover of encroaching tall grasses and shrubs.
• Absence of invasive alien species.

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats