2.4 VEGETATION

Data concerning the vegetation have been extracted from the report of Buys (1987)   This oceanic mire complex consists mainly of bogs. In about 10 percent of the area fens have developed under influence of more mineral‑rich water. This water originates from the surrounding mountains, or is seeping out of the bogs and is probably enriched by the subsoil of the bogs. Both fens and bogs show a wide morphological variation. For desmids the most important feature is that many of the hollows and flarks (the wet parts of the mire) are permanently filled with a few decimeter of water forming an enumerable number of pools

  Roughly  two  major  fen  types  may  be  distinguished.  (Chemical  differences  are schematic). One fen type is fed by springs from the surrounding mountains, chemically characterized by a 1:3 Mg:Ca ratio, morphologically by numerous occurrence of flark pools and strings, and botanically by the presence of Molinea caerulea, Carex panicea, Calliergon trifarium. Also Phragmites australis occurs frequently.

  The  second  fen  type  is  fed  by  springs  in  the  middle  of  the  mire,  chemically characterized by a 1:5 in some cases 1:10 Mg:Ca ratio, morphologically by a smaller and  less  orderly  arranged  small  relief,  and  botanically  by  species  like  Comarum palustre,  Carex  chordorrhiza,  Equisetum  fluviatile,  Calamagrostis  neglecta,  Oxycoccus quadripetalus,  Drepanocladus  purpurascens,  and  others.  Many  of  these  species  are characteristic for what Eurola and Kaakinen (1980) call swamp influence. Phragmites australis occurs in well defined plant communities.   The transition between bogs (which show a Mg: Ca ratio of less then 2:3) and fens of the first type may be very subtile. It occurs in wide bands or narrow zones between the two.

  On the wettest places, the major habitats for desmids, different combinations of mosses can be observed. These vegetations are so wet that all Ericaceae are lacking. In general the oligotrophic and meso‑eutrophic vegetation types are common, those in between less common. The vegetation types that have been sampled for desmids are listed below. The name of the type is preceded by the code number in Buys (1987).

Andromeda‑ Gymnocolea hollow vegetation, oligotrophic. This vegetation occurs on the transition  between  hummocks  and  hollows,  or  in  pure  lawns  in  oligotrophic  mire expanse situations.

  1. Sphagnum papillosum‑S. lindbergii community. Almost always a closed Sphagnum      layer in  which  both  mentioned  species  are  important.  Varied  graminid  layer.      Develops in the transition between hummocks and hollows (which can occupy a      large surface). Drier than '10'.

  2. Sphagnum  balticum‑  S.  tenellum  community.  Both  low‑productive  species  often      dominate. Scirpus caespitosus and Andromeda polifolia and other dwarfshrubs are      usually present, but in low coverage. In lawnlike‑mudbottom situations in bogs.

Sphagnum  angustifolium  vegetation,  oligotrophic.  This  vegetation  develops  under mire‑margin conditions, as lawns or carpets. A slight minerotrophic influence is typical.

  1. Eriophorum angustifolium‑Sphagnum riparium community. Moss layer of Sphagnum      angustifolium  and  S.  riparium.  Well  developed  field  layer,  with  Rubus      chamaemorus,  Empetrum  hermaphroditum,  Vaccinium  uliginosum  and  Cornus      suecica. This lawn community develops around lakes or larger pools. Drier than '9'.

  2. Carex rostrata‑Sphagnum riparium community. Looks like '8' but  Carex  rostrata  is      dominant, Sphagnum squarrosum occurs and the field layer species of '8' lack. A      lawn community which develops around lakes or near oligotrophic springs.

Oligotrophic wet hollow and pool vegetation. This vegetation grows on the wettest sites in bogs. Dwarfshrubs and herbs only occur incidentally. The vegetation is build up by an open graminoid layer, and a rich to very scanty moss layer that consists only of the most wet‑tolerant oligotrophic species.

  1. Sphagnum majus‑S. lindbergii community. A floating mat or wet carpet community,      dominated by Sphagnum majus and S. lindbergii . The most important vascular      plants are Eriophorum angustifolium and Carex limosa. Very common in smaller      deep bog pools.

    Sphagmum auriculatum community. Rare, occurs in deep pools in extremely poor      fens.

  2. Gymnocolea‑Carex limosa community. Dominated by Gymnocolea/ Cladopodiella or      bare peat. Sphagnum species occur, but in low cover. The field layer is very      open, with vascular plants as in '10', supplemented by Scirpus caespitosus. This      common community develops in wet hollows or mudflats, on locations with a      fluctuating water table, often near the edge of the mire.

Oligo‑mesotrophic wet flark  vegetation.  This  vegetation  concerns  flarkpools  and  wet mudbottom‑like structures, in oligo‑mesotrophic areas.  Characteristic  moss  species  are: Sphagnum  annulatum,  S.  plathyphyllum  and  Drepanocladus  procerus.  These  species indicate a nutrient status intermediate between oligotrophic and mesotrophic situations. The field layer is better developed than in '10' and '11'. Of the dwarf shrubs only Andromeda polifolia occurs sporadically.

  1. Drepanocladus  procerus‑Sphagnum  lindbergii  community.  Sphagnum  lindbergii,  S. annulatum,  S.  platyphyllum  and  Drepanocladus  procerus  and  Gymnocolea/      Cladopodiella are characteristic. Vascular plants as in '11', with addition of Carex      rostrata, C. limosa, C. livida  and  Menyanthes  trifoliata.  The  community  is  not      really common in flark pools.

  2. Sphagnum  plathyphyllum‑Scorpidium  community.  Consists  of  a  combination  of      Sphagnum annulatum, S. platyphyllum, Drepanocladus procerus, D. revolvens and      Scorpidium scorpioides. Vascular plants as in '12'. It generally develops in deeper      flark‑pools than '12' and pH and cation content are higher.

(Oligo)‑mesotrophic lawn and low hummock vegetation. This type of vegetation occurs on low strings or lawns in intermediate fens. Rich fen species occur only sporadically, and Sphagnum species dominate the moss layer. The two communities share a high frequency of Betula nana, Menyanthes trifoliata, Scapania sp., Calliergon stramineum and Viola palustris.

  1. Sphagnum  subsecundum‑S.  papillosum  community.  Species‑rich,  hardly  swamp      influence.

  2. Sphagnum teres‑Mnium community.  Distinct  swamp  influence.  Intermediate  level.
Meso‑eutrophic wet flark vegetation. This vegetation forms mudbottoms or carpets in mesotrophic flark pools, moist parts of  mesotrophic  lawns  and  around  streams.  It  is floristically characterized in the first place by Scorpidium scorpioides  which  usually constitutes a large part of the moss layer. Both moss and graminoid‑layer are better developed  than  in  the  oligo‑mesotrophic  wet  flark  vegetation.  Swamp  influence  is hardly visible. The oligo‑ mesotrophic species that characterize the former vegetation arerare.
  1.  Scorpidium   community.   Scorpidium   scorpioides   dominating,   mixed   with   Drepanocladus revolvens, Calliergon trifarium, and Campylium stellatum. The last   two species are low in abundance and characteristic for a higher trophic status   within  the  community.  Many  grasses  and  herbs  occur  here.  Very  common.   Develops under different moist conditions, from wet‑lawn to pool vegetation.

  2. Carex oederi community. Variant of '14'. A rare wet mudbottom community in fens  that are in contact with bogs.

  3. uncus alpinus community. Variant of '14'. It develops as mudbottoms on sites with  superficial water run‑off and shows a pioneer character. Along small streams or  muddy places with spring influence.

  4. Carex buxbaumii community. Variant of '14', which develops in the vicinity and    under influence of small fen streams.

Meso‑eutrophic  lawn  and  hummock  vegetation.  This  vegetation  includes  lawns, hummocks and strings in meso‑eutrophic fens.

  1. Campylium‑Drepanocladus  revolvens  community.  Dominated  by  Drepanocladus  revolvens and Campylium stellatum. This vegetation grows on drier sites than '14'.  Only on the most nutrient‑rich localities in the flark pool‑string area, or along  nutrient‑rich  streams  it  is  wet  enough  for  the  collection  of  desmids.  Here  Eriophorum latifolium is a characteristic species.

Mesotrophic to eutrophic vegetation with swamp character. Characteristic species are Comarum  palustre,  Calamagrostis  neglecta,  Drepanocladus  purpurascens,  Equisetum fluviatile, Oxycoccus quadripetalus, Sphagnum teres, Mnium rugicum/cinclidioides, and as  for  Andøya  this  list  can  be  completed  with  Carex  chordorrhiza,  Calliergon sarmentosum and Pedicularis palustris, and maybe also more scarcely occurring species as Calliergon richardsohnii and Sphagnum contortum might be added.

18 Chara‑Calliergon giganteum community. The most nutrient rich (eutrophic) type of      this mire. Except for the species mentioned, and many swamp species, also Carex      diandra is characteristic. This community develops in springs in the mire expanse,      which occur as very deep pools.

19 Calliergon sarmentosum‑Drepanocladus purpurascens community. In addition to the      species mentioned above it shows a very species‑ rich moss layer due to minor      height differences around the waterline. Oligo‑mesotrophic as in '12' and '13' but      notably more rich in sulphate. No Carex chordorrhiza, but a varying fieldlayer      with regularly Phragmites australis, Triglochin palustre and Andromeda polifolia. It      grows in very shallow pools, drier than '13'.

20 Sphagnum subsecundum‑Drepanocladus purpurascens community. Characterized by      the  above‑mentioned  species,  and  a  moderate  swamp  influence.  It  occurs  on      transitional places between 'normal' fens and swamp fens. The vascular plants are      similar to those in the oligo‑mesotrophic types ('12' and '13'). Also the trophic status      is comparable. It develops just above the water surface in shallow waters. It is      periodically inundated. Slight swamp influence, less than '19' and '21'.

21 Carex chordorrhizza  community.  Characterized  by  the  name  giving  species.  The      numerous swamp species are common, just as Andromeda polifolia. The trophic      status varies from 'rich' oligo‑mesotrophic ('13') to meso‑eutrophic. This is the most      common swamp comunity.

Narthecium vegetation.

22 Narthecium‑Sphagnum papillosum community. Dominated by Narthecium ossifragum.      It is a moist lawn community, which is permanently wet but rarely inundated.      There is always a superficial water run‑off.

Spring and spring meadow vegetation.

27 Phylonotis community. The vegetation is quite heterogeneous, with many herbs and      graminoids. Important mosses are Phylonotis fontana, Cratoneuron decipiens  and      Bryum pseudotriquetrum.

Fontinalis vegetation. Recorded once, near a spring with a constant temperature at a shady place.

Mossless pool and lake vegetation. Many (bog) pools without mosses bear no vegetation at all. Lake shores may be mossless due to erosion. Here Carex rostrata, Phragmites australis, Equisetum fluviatile and Menyanthes trifoliata can form facies.