Artikkelit jotka sisältää sanan 'aapa mire'

Maankohoamisesta johtuvan rannansiirtymisen tuloksena on Perämeren rannikolle syntynyt aapasoiden nuorista kehitysvaiheista koostuvia sukkessiosarjoja. Ne ovat ekologisesti ja tieteellisesti arvokkaita ekosysteemejä, jotka ovat ainutlaatuisia maailmassa. Näiden soiden ekologiaa ja nykyistä tilaa on kuitenkin tutkittu verrattain vähän. Tämän tutkimuksen tavoitteena oli tuottaa tietoa aapasoiden nuorten kehitysvaiheiden suojeluarvon ja niiden säilymiseen liittyvien uhkien arviointiin ja selvittää soistumiseen liittyviä syitä sekä kasvillisuuden ekologisten vaihtelusuuntien ilmenemistä hydrologialtaan erilaisissa osissa suoaltaita. Tässä tutkimuksessa esitetään tuloksia nuorten (alle 2000 vuotta), luonnontilaisten aapasoiden määrän arvioinnista ja niiden kasvillisuuskartoituksesta kahdelta laajimmalta yhtenäiseltä aapasoiden sukkessiosarja-alueelta Perämeren rannikolla. Alueista toisen maaperä on moreenivaltainen ja toisen hiekkavaltainen. Tulokset osoittivat, että aapasoiden kehitysvaiheissa on suuri osa lettomaisia ja keskiravinteisia nevoja ja vain hyvin rajallinen määrä rahkasammalten kasvusta eroaa rämeiden sukkession alkuvaiheiden kehityksestä. Aapasoiden sukkessiosarjat ulottuvat koko valuma-alueen soistumiseltaan useiden satojen hehtaarein alueelle. Hydrologialtaan erilaiset valuma-alueen osat kehittyvät yhdessä muodostaen yhden kokonaisuuden. Vedenjakajien tuntumassa primääristä soistumista ilmenee pienien painanteiden ja lampien soistumisena, missä rahkasammalten kasvu painanteiden yli on hyvin nopeaa. Valuma-alueen alajuoksun osissa primääristä soistumista tapahtuu laajoilla märillä luhdilla, jossa veden virtaus on voimakasta. Myöhempi suon kehitys, jossa tapahtuu mm. ympäröivien kangasmetsien soistumista näyttää johtavan aapasuokompleksin muodostumiseen, jossa reunaosat ovat rahkasammalen vallitsemia ja keskusosat rimpipintaisia. Tulokset osoittavat, että nuorten aapasoiden suojelussa olisi olennaista kiinnittää huomiota soistuvien valuma-alueiden hydrologian säilyttämiseen. Valitettavasti hyvin harvat tällaisista valuma-alueista ovat enää nykyisin luonnontilaisia.

• Rehell, Sakari Rehell, Metsähallitus, luontopalvelut, PL 81, FI-90101, Oulu, Finland. e-mail: sakari.rehell@metsa.fi Sähköposti: ei.tietoa@nn.oo
• Heikkilä, Sähköposti: ei.tietoa@nn.oo

An attempt is made in this paper to create two consistent mire typologies, i.e. 1) the Combined Finnish Mire Typology covering all possible mire areas in Finland and 2) the Mire Water Flow Typology for boreal, zonal mire systems, i.e. aapa mires and raised bogs. Furthermore, larger groundwater recharge-discharge patterns concerning mires and the biological significance of morphologic and hydrologic mire classifications are discussed. Zonal mire systems from raised bogs to aapa mires are described as a dominance-based continuum. Local mire systems are subdivided according to factors that impede the formation of mire massifs, which are the essential morphological units of zonal mire systems. Smaller-scale mire units for aapa mires and the acrotelmic flow pattern are presented on the basis of a typical mid-boreal aapa mire system with a raised bog, based on the aerial photograph interpretation. The discussion of the groundwater recharge-discharge pattern and the biological significance of morphologic and hydrologic mire classifications is based on literature.

• Laitinen, University of Oulu, Department of Biology, Botany, P.O.Box 3000, FI-90014, Finland Sähköposti: ei.tietoa@nn.oo
• Rehell, Sähköposti: ei.tietoa@nn.oo
• Huttunen, Sähköposti: ei.tietoa@nn.oo
• Tahvanainen, Sähköposti: ei.tietoa@nn.oo

The present paper introduces and describes a poorly known wetland type – aro wetland – in well permeable mineral soil substratum in Northern Ostrobothnia and Kainuu (between 64° – 66° N lat.). Field observations (linked with the interpretation of aerial photographs) were made in 32 localities, whose conservation status is presented. We define boreal aro wetlands ecologically as a seasonal wetland type of their own which occur on well-drained mineral soil, which are mainly characterised by treeless, mire expanse fen vegetation and in which the peat accumulation is (almost) totally hampered by the vigorous decomposition of the organic matter resulting from an extremely unstable water regime (flood and seasonal drought) and small plant production. Aro wetlands in the western part of the study area occur on sandy substratum (the largest in parts of mire complexes split by ancient raised beach ridges), whereas in the eastern part the aro wetlands known so far are small pond-like depressions in till substratum. Carex lasiocarpa (mostly) dominates the vegetation on sandy substratum. Juncus filiformis and Carex nigra are typical, and Rhynchospora fusca and Molinia caerulea a bit rarer. Sphagnum cover is usually minimal. Considering aro wetlands an extreme case of suo (mire) makes the stability of water regime (stable – unstable) a direction of variation in the traditional Finnish mire site type system, which is based on several ecological gradients.

• Laitinen, University of Oulu, Department of Biology, Botany, P.O.Box 3000, FI-90014, Finland Sähköposti: ei.tietoa@nn.oo
• Rehell, Sähköposti: ei.tietoa@nn.oo
• Huttunen, Sähköposti: ei.tietoa@nn.oo
• Eurola, Sähköposti: ei.tietoa@nn.oo

This case study deals with the effects of forest drainage on six mire site types represented by 33 permanent sample plots within a Finnish aapa mire complex located in north boreal vegetation zone. We analysed the main compositional gradients, the abundances of plant species and the diversity of vegetation. The vegetation descriptions were made about at the time of drainage in 1933 and after that in 1943, 1950 and 1994. The forest drainage emphasized the importance of spruce mire and hummock-level bog influences (mire margin and mire expanse effects respectively) in controlling the structure of plant communities. The change of plant community was greatest on fertile mire site types, also spruce mire influence promoted the secondary succession. As expected, the shallow-rooted and/or demanding flark-level vascular plants and (eutrophic) fen mosses had not been able to adapt to the ground water level drawdown. At first, after drainage, species number, Shannon's H' and Simpson's D increased: many mire species of hummock and intermediate level microsites had increased while also pioneer and forest species had colonized the plots. By 1994, however, as the mire species were decreasing these measures had turned to decline except on the (most) infertile site types. Pielou's J' and the evenness based on D reacted vaguely, decreasing a little, though, from 1933 to 1994. Thus, in such cases the dominance in the vegetation had increased. The beta-diversity describing here the differences between plant communities (or site types) decreased along with the hydrological conditions becoming more uniform after drainage.

• Hotanen, The Finnish Forest Research Institute, Joensuu Research Station, P.O.Box 68, FIN-80101 Joensuu, Finland Sähköposti: ei.tietoa@nn.oo
• Nousiainen, Sähköposti: ei.tietoa@nn.oo
• Paalamo, Sähköposti: ei.tietoa@nn.oo

The percentage distribution of mire site types on 49 random sample plots (1/4 km2) was studied in 1989. The line transect method was used, the total mire transect line on the sample plots being 100,6 km. The eight most common mire site types include different pine bog types (hummock level bogs/pine mires) and fens. Both poor fens and rich fens are more common in Kuusamo than in the Pohjanmaa aapa mires (southern aapa mires), the former ones taking 29% and the latter ones 8% of all mires. The percentage of spruce mires (6% ) is no more than a half of their percentage in the Pohjanmaa aapa mires. 32% of the peatlands studied were under the influence of drainage, mainly with open ditch networks for forestry. 16% of those were classified as recently drained, 73% as transitional, 5% as drained peatland forests and 6% as being influenced by drainage in the vicinity. Open fens and thick peated mire types have been drained to a lesser extent than forested mires and sites with mire margin effect. However, as only few mire site types are suitable for forestry in northern Finland, the risk of unprofitable drainage is high. Mire site types considered unsuitable for forestry even in the more favourable conditions of southern Finland take about 35% of the drained mires. Keywords: Aapa mire area, draining for forestry, field survey, mire vegetation, Peräpohjola

• Paasovaara, Keskuskoulu B 7, FIN-86710 Kärsämäki, Finland Sähköposti: ei.tietoa@nn.oo

The occurrence of the threatened and endangered vascular mire plant species was inventoried in the mire conservation areas in Finland. The survey was based on 246 sample plots (0.5 km × 0.5 km) randomly chosen in the Finnish mire conservation areas planned in 1981 in southern and central Finland. In the inventory, 243 vascular plant species and 2 hybrids were found in bog mires and 249 species and 10 hybrids were found in the southern aapa mires. The majority of the found mire plant species commonly occur on mires in Finland. In this survey, out of 18 threatened primary mire vascular plant species occurring in Finland, only three species (Carex heleonastes L. f., Dactylorhiza incarnata ssp. cruenta (O. F. Mull.) P. D. Sell, D. cruenta (O. F. Mull.) Verm, Orchis cruenta (O. F. Mull.) and Dactylorhiza traunsteineri) (Saut. ex Rchb.) Soo´, Orchis traunsteineri Saut. ex Rchb., Dactylorchis traunsteineri (Saut. ex Rchb.) Verm.; incl. Dactylorhiza curvifolia (F. Nyl.) Czerep.; incl. D russowii (Klinge) Holub and only one so called secondary mire plant species (Carex paniculata L.) were found in the sample plots. The found species occurred only on six mire conservation areas. Compared to the size of the material, the percentage of findings of threatened vascular plant species was remarkably low. It can be concluded that the complementary programs of the mire conservation in Finland have been important to protect the threatened vascular mire plants.

• Hanhela, Oulu University of Applied Sciences, School of Renewable Natural Resources, Metsäkouluntie, FI-90650 Oulu Sähköposti: ei.tietoa@nn.oo