C13: West Norwegian birch forests (Betula pubescens, Betula pubescens subsp. czerepanovii), partly with Corylus avellana, in combination with pine forests (Pinus sylvestris) and nemoral mixed broad-leaved forests (Alnus glutinosa, Quercus robur, Ulmus glabra, Fraxinus excelsior)

Title

West Norwegian birch forests (Betula pubescens, Betula pubescens subsp. czerepanovii), partly with Corylus avellana, in combination with pine forests (Pinus sylvestris) and nemoral mixed broad-leaved forests (Alnus glutinosa, Quercus robur, Ulmus glabra, Fraxinus excelsior)

Geographical distribution

Scientific names of main plant communities and their most common synonyms (with author citation)

a) Corno-Betuletum Aune 1973 (syn.: Corno-Pinetum Kielland-Lund 1971 n.n.); b) Melico-Betuletum Aune 1973; c) Bazzanio-Pinetum Kielland-Lund 1981.

Structural feature of the main community(ies) (layers, life-forms, etc.)

The Corno-Betuletum encompasses the most impoverished birch forests and the closely related pine-birch forests. The tree layer is quite dense with an average coverage of 60 % and reaches up to 6 m in height particularly in protected locations in the valleys and fjords. The Melico-Betuletum contains the species-richest birch forests. In the tree and shrub layers some pines, grey alders, hazel and asps also appear. Herbs and grasses form a species-rich herb layer. In the open tree layer of the Bazzanio-Pinetum, Pinus sylvestris is the only species of any major importance while Juniperus communis is always present in the shrub layer. The herb layer is dominated by well developed Ericaceae species. A marked moss layer is developed from mosses and lichens. This association can be found on poor and shallow soils.

Dominant and most frequent species in different layers

Diagnostically important species

SEQ CHAPTER \h \r 1Betula pubescens s.l., Pinus sylvestris; a) Dryopteris expansa, Lycopodium annotinum, Plagiothecium undulatum, Lophozia obtusa, Polytrichum formosum, Tritomaria quinquedentata; b) SEQ CHAPTER \h \r 1Corylus avellana; Anemone nemorosa, Hieracium murorum agg., Melampyrum sylvaticum, Pyrola rotundifolia, Rubus saxatilis, Carex pallescens, Carex pilulifera, Fragaria vesca, Veronica chamaedrys, Veronica officinalis, Viola riviniana, Isothecium alopecuroides; d) SEQ CHAPTER \h \r 1Alnus glutinosa, Quercus robur, Fraxinus excelsior

Ecological variants

Corno-Betuletum with four subassociations: - myrtilletosum: Tree layer frequently influenced by the pine; in the species-poor herb layer, Vaccinium myrtillus dominates with a high degree of coverage; it is negatively differentiated by the absence of a number of species from the other subassociations; - dryopteridetosum: is species-richer than the myrtilletosum with Phegopteris connectilis, Hylocomium umbratum, Lophocolea bidentata, Cirriphyllum piliferum, Gymnocarpium dryopteris and Oxalis acetosella. The herb layer is typified by a characteristic mixture of Vaccinium myrtillus and the two small ferns Gymnocarpium dryopteris and Thelypteris phegopteris; - athyrietosum: is dominated by Athyrium filix-femina with the differential species: Carex vaginata, Solidago virgaurea, Plagiomnium affine; - thelypteridetosum: with Oreopteris limbosperma is species-richer than the athyrietosum and shows a certain affinity to the following association, the Melico-Betuletum. The subassociations athyrietosum and thelypteridetosum are found on richer soils influenced by seeping waters. The Melico-Betuletum consists of three subassociations: - cornetosum: on somewhat moister and cooler sites with Cornus suecica, Hylocomium umbratum, Polytrichum formosum, Ptilium crista-castrensis. In the herb layer, Vaccinium myrtillus shows the highest degree of coverage. In most herb- and grass-rich stands the proportion of Vaccinium myrtillus is smaller. Small ferns such as Blechnum spicant, Gymnocarpium dryopteris and Thelypteris phegopteris are frequent. Anemone nemorosa forms the spring aspect; - coryletosum: at steep warm valley slopes with stony and somewhat unstable soil with Corylus avellana in the shrub layer and Campanula rotundifolia, Epilobium montanum, Luzula multiflora, Hypnum cupressiforme, Isothecium alopecuroides, Radula complanata in the field layer; - athyrietosum: encompasses luxuriant, seeping moist sites with large ferns and tall herbs, e. g. Aconitum lycoctonum subsp. lycoctonum, Athyrium filix-femina, Calamagrostis purpurea, Carex vaginata, Cirsium heterophyllum, Dryopteris filix-mas, Filipendula ulmaria, Hypericum maculatum, Phalaris arundinacea, Pteridium aquilinum, Rubus idaeus, Oreopteris limbosperma, Viola palustris, Plagiomnium affine. In the Bazzanio-Pinetum, Vaccinium uliginosum can prevail on moister sites. The locally occurring species Cornus suecica or Blechnum spicant can occur together with the remaining species in a dominating manner; Bazzanio-Pinetum sphagnetosum Aune 1973, Bazzanio-Pinetum racomitrietosum lanuginosi Aune 1973.

Geographical variants (geogr. differential species)

No details

Natural accompanying vegetation (most important units in complex with the name giving mapping unit, scientific names)

Populo-Quercetum, Melico-Quercetum, Carici nigrae-Alnetum glutinosae; atlantic Racomitrium lanuginosum bogs, heaths with Violion and Calluno-Genistion communities; on hilltops fragments of the Primulo-Ulmetum, Eurhynchio-Fraxinetum.

Adjoining climax and permanent vegetation (with numbers of mapping units)

high mountain vegetation (A4), alpine vegetation (B41, B42), birch forests (C9, C15), pine forests (D45, D46), oak-ash forests (F27).

Land use, substitute communities

Site conditions of the mapping unit

Importance for nature protection

Localities of representative stands (loci typici) with state of protection

Most important references (author, year)

Aune 1973; Bakkevig 1974; Bjørnstad 1971; Blom, Røsberg & Skjolddal 1982; Kielland-Lund 1967b; Kielland-Lund 1973; Malme 1971; Øvstedal 1985; Seibert 1969

Compiled by

O. Vevle