Red List habitat classification > RLH - Sparsely vegetated habitats > RLH2.1 Boreal and arctic siliceous scree and block field

Boreal and arctic siliceous scree and block field

Quick facts

Red List habitat type code RLH2.1
Threat status
Europe Least Concern
EU Least Concern
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)

Summary

This habitat type includes all kinds of boreal and arctic unvegetated accumulations of siliceous boulders, stones or gravel, except for the littoral habitats. They form a base-poor substrate that harbours acidophilous plant communities. The habitat type is heterogeneous in regard to its biota, as it extends from the small blockfields of the southern boreal taiga to the highlands of Iceland. Screes and blockfields are produced by various geological processes. Scree usually refers to a collection of broken rock fragments on slopes or under cliffs produced by slope processes (also called talus formations). Screes often show a sorting of rock fragments. The largest blocks falling off from cliff faces roll down the furthest, whereas the finest material accumulates in the uppermost part of the slope. Other boulder and gravel fields originate from glacial deposition, frost action breaking rock outcrops in situ, or e.g. frost heaving from moraine. Rock glaciers and ice-dominated moraines are distinguished as a separate habitat H4.3, however. Yet another type of boulder fields is related to ancient beach deposits constituted by former coastal constructional processes. Sparsely vegetated screes and block and gravel fields are distributed across the whole boreal and arctic region but with varying abundance. The largest screes are found in Iceland (incl. gravel fields) and along the Scandinavian Mountain range, where they reach mid- or high-alpine levels. Large stable blockfields cover mountaintops in northern Fennoscandia and some quite large ancient beach deposits encircle high hills along the ancient coasts of the Baltic Sea. The vegetation of scree slopes represents a complex that covers many vegetation types from forests at the foot of the slopes to scrubs and sparsely vegetated unstable screes in the upper parts of formations. The forest and scrub types are not included in the habitat described here, but included under G- and F-types, respectively. More or less flat boreal blockfields may be also covered by trees or sometimes by scrubs, but also in this case, the habitat type in question only refers to open areas that do not have a tree or scrub layer. In such screes, the most characteristic assemblages of vascular plants are found in unstable patches, where also weak competitors can persist. In other blockfields, the role of vascular plants is small. The vegetation typically consists of lichens and bryophytes with different growth forms dominating different microhabitats, e.g. crustose and foliose lichens and small cushion-forming bryophytes on the sides of boulders, and fruticose lichens and mat-forming bryophytes in the hollows between blocks. Where vascular plants find enough soil between blocks, they form sparse vegetation. Transitions may occur towards grasslands or heathlands while near mountain summits transitions towards fjell-fields (H5.1) may be found. Probably the most important steering factor in screes and blockfields is a natural or semi-natural disturbance regime, which maintains characteristic species assemblages. In the arctic, gravel and blockfields are kept open just by the harsh climate, but in the boreal zone slow overgrowth has been observed in some regions. In screes, the disturbance regime is characterized by the continuum of periodic rockfall, instability of the substrate, and in some regions also by the long tradition of grazing. In some cases, grazing or, e.g., hiking or mountaineering activities may cause additional erosion in the habitat to such an extent that it disturbs the formation of typical vegetation. In forested areas, especially small blockfields tend to become more and more vegetated, starting gradually from the margins. In these habitats, the characteristic scarce vegetation may be in the long run dependent on regular forest fires.

Indicators of good quality:

  • natural or seminatural disturbance regime, with a continuum of periodic rockfall and instability of the substrate or (in some cases) forest fires
  • no or little succession towards scrub and forest
  • continuation of traditional grazing (where relevant)
  • no disturbance (for example by hiking, grazing, etc.)
  • diversity of lichen, moss, and vascular plant species

Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

The habitat is assessed as Least Concern (LC) under criterion A1 in both EU28 and EU28+. There is no direct or indirect evidence or suspicions about significant quantitative changes in the habitat within the last 50 years. A small proportion of habitat type occurrences has been destroyed in various construction projects and changed into woodland or scrub habitat types through overgrowth. Human-induced overgrowth may have caused also some changes in the vegetation and species composition (especially in the southern part of the boreal zone) but all in all qualitative changes are regarded slight, leading to the same category (Least Concern) under criterion C/D1. It should be noticed that actual data about the quantity and quality of the habitat was received only from Finland, and the overall status was inferred from that data and from general knowledge about potential threats within the boreal zone.
EU
Red List Category Red List Criteria
Least Concern -
Europe
Red List Category Red List Criteria
Least Concern -

Confidence in the assessment

low
Red List of habitat categories and criteria descriptions

Pressures and threats

  • Agriculture
    • Non intensive grazing
  • Sylviculture, forestry
    • Forest replanting (native trees)
  • Geological events, natural catastrophes
    • Earthquake
    • Collapse of terrain, landslide
  • Climate change
    • Temperature changes (e.g. rise of temperature & extremes)

Habitat restoration potential

The recovery of the habitat is possible but requires the existence of natural processes over a long time-period.

Trends in extent

Average current trend in quantity

Stable Stable
EU28 EU28+

Trends in quality

Average current trend in quality

Stable Stable
EU28 EU28+

Conservation and management needs

The most important steering factor in Boreal and Arctic siliceous screes and block fields is a natural or semi-natural disturbance regime, which maintains characteristic species assemblages. Due to the necessity of natural processes, only the establishment of protected areas is an optimal regime for environmental policy and conservation.

List of conservation and management needs

  • Measures related to spatial planning
    • Establish protected areas/sites
    • Manage landscape features

Distribution

For each habitat a distribution map was produced from a wide variety of sources indicating known and potential occurrences of the habitat in 10x10 km grids within Europe. Occurrences in grid cells were given in two classes: actual distribution from relatively reliable sources (surveys, expert knowledge), and potential distribution based on models or less reliable indicators. Please download the fact sheet to see the map.

Geographic occurrence and trends

EU28 Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Finland mainland Present 700 Stable Stable
Aland Islands Present 700 Stable Stable
Sweden Present Unknown Unknown Unknown
United Kingdom Present Unknown Unknown Unknown
EU28 + Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Iceland Present Unknown Unknown Unknown
Norway Mainland Present Unknown Unknown Unknown
Svalbard Present Unknown Unknown Unknown
Jan Mayen Present Unknown Unknown Unknown

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 950000 93 >700
EU28+ 222 Unknown
AOO = the area occupied by a habitat measured in number of 10x10 km grid cells.
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).

Characteristic species

The full list of characteristic species and genus are available above from the Summary. The species available in the EUNIS database are shown here.
Conifers Juniperus communis
Ferns Cryptogramma crispa
Ferns Cystopteris fragilis
Ferns Dryopteris carthusiana
Ferns Equisetum variegatum
Ferns Gymnocarpium dryopteris
Ferns Huperzia selago
Ferns Polypodium vulgare
Ferns Polystichum lonchitis
Ferns Woodsia ilvensis
Flowering Plants Alchemilla alpina
Flowering Plants Arabis alpina
Flowering Plants Arctostaphylos uva-ursi
Flowering Plants Arenaria norvegica
Flowering Plants Armeria maritima
Flowering Plants Calamagrostis epigejos
Flowering Plants Campanula rotundifolia
Flowering Plants Cardaminopsis petraea
Flowering Plants Carex bigelowii
Flowering Plants Cerastium alpinum
Flowering Plants Deschampsia alpina
Flowering Plants Draba daurica
Flowering Plants Dryas octopetala
Flowering Plants Empetrum nigrum
Flowering Plants Epilobium angustifolium
Flowering Plants Erysimum strictum
Flowering Plants Festuca ovina
Flowering Plants Galium normanii
Flowering Plants Gentiana nivalis
Flowering Plants Hieracium alpinum
Flowering Plants Juncus trifidus
Flowering Plants Lotus corniculatus
Flowering Plants Luzula arcuata
Flowering Plants Minuartia biflora
Flowering Plants Oxyria digyna
Flowering Plants Papaver radicatum
Flowering Plants Poa alpina
Flowering Plants Polygonatum odoratum
Flowering Plants Potentilla crantzii
Flowering Plants Ranunculus glacialis
Flowering Plants Rhodiola rosea
Flowering Plants Rosa villosa
Flowering Plants Rubus idaeus
Flowering Plants Salix herbacea
Flowering Plants Saxifraga aizoides
Flowering Plants Sedum annuum
Flowering Plants Silene acaulis
Flowering Plants Solidago virgaurea
Flowering Plants Thalictrum alpinum
Flowering Plants Tofieldia pusilla
Flowering Plants Trisetum spicatum
Flowering Plants Vaccinium myrtillus
Flowering Plants Verbascum nigrum
Flowering Plants Verbascum thapsus
Flowering Plants Veronica fruticans
Flowering Plants Vicia sylvatica
Flowering Plants Viscaria alpina
Mosses & Liverworts Dicranum scoparium
Mosses & Liverworts Pleurozium schreberi
Mosses & Liverworts Racomitrium lanuginosum
Species scientific name English common name Species group
Juniperus communis Conifers
Cryptogramma crispa Ferns
Cystopteris fragilis Ferns
Dryopteris carthusiana Ferns
Equisetum variegatum Ferns
Gymnocarpium dryopteris Ferns
Huperzia selago Ferns
Polypodium vulgare Ferns
Polystichum lonchitis Ferns
Woodsia ilvensis Ferns
Alchemilla alpina Flowering Plants
Arabis alpina Flowering Plants
Arctostaphylos uva-ursi Flowering Plants
Arenaria norvegica Flowering Plants
Armeria maritima Flowering Plants
Calamagrostis epigejos Flowering Plants
Campanula rotundifolia Flowering Plants
Cardaminopsis petraea Flowering Plants
Carex bigelowii Flowering Plants
Cerastium alpinum Flowering Plants
Deschampsia alpina Flowering Plants
Draba daurica Flowering Plants
Dryas octopetala Flowering Plants
Empetrum nigrum Flowering Plants
Epilobium angustifolium Flowering Plants
Erysimum strictum Flowering Plants
Festuca ovina Flowering Plants
Galium normanii Flowering Plants
Gentiana nivalis Flowering Plants
Hieracium alpinum Flowering Plants
Juncus trifidus Flowering Plants
Lotus corniculatus Flowering Plants
Luzula arcuata Flowering Plants
Minuartia biflora Flowering Plants
Oxyria digyna Flowering Plants
Papaver radicatum Flowering Plants
Poa alpina Flowering Plants
Polygonatum odoratum Flowering Plants
Potentilla crantzii Flowering Plants
Ranunculus glacialis Flowering Plants
Rhodiola rosea Flowering Plants
Rosa villosa Flowering Plants
Rubus idaeus Flowering Plants
Salix herbacea Flowering Plants
Saxifraga aizoides Flowering Plants
Sedum annuum Flowering Plants
Silene acaulis Flowering Plants
Solidago virgaurea Flowering Plants
Thalictrum alpinum Flowering Plants
Tofieldia pusilla Flowering Plants
Trisetum spicatum Flowering Plants
Vaccinium myrtillus Flowering Plants
Verbascum nigrum Flowering Plants
Verbascum thapsus Flowering Plants
Veronica fruticans Flowering Plants
Vicia sylvatica Flowering Plants
Viscaria alpina Flowering Plants
Dicranum scoparium Mosses & Liverworts
Pleurozium schreberi Mosses & Liverworts
Racomitrium lanuginosum Mosses & Liverworts

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

This habitat may be equivalent to, or broather than, or narrower than the habitats or ecosystems in the following typologies.
Classification Code Habitat type name Relationship type
EUNIS Habitat Classification 200711 H2.1 Cold siliceous screes same
European Environment Agency (EEA)
Kongens Nytorv 6
1050 Copenhagen K
Denmark
Phone: +45 3336 7100