Peatlands (the first section)
North Finnish peatlands (wetlands, mires) are mainly aapa mires...
(English terminology of peatlands is to a great extent incoherent. In this connection the terms peatland, wetland and mires are in common use. The mire is used especially in Scandinavian countries.)
Similar climatic and humidity conditions lead to similar mire complexes and complex types. There are in Finland mainly two mire complex types: raised bogs and aapa mires (see map!).
The mire zones on the map somewhat resemble the forest vegetation zones. This is quite understandable, because these kinds of boundaries are affected by climatic factors.
Aapa mire region can be divided into four different zones: (Metsä-Lappi, Peräpohjola and Pohjanmaa). The northernmost palsa bogs with permafrost can also be included in aapa mires.
The main part of mire complex types in North Finland are aapa mires. The central area of an aapa is often wet (open flarks and sedge-dominated fens). The margins are usually drier (pine mires with dwarf shrubs).
The mire complex types of South Finland are raised bogs: central area of a mire is higher than margins and rather dry (nevertheless it can exist some water trugh in central part). In the margins exist often minerotrophic fens (fen = a rather fertile peatland) and spruce swamps.
The water ecology is different in aapa mires than in raised bogs: aapa mires are minerotrophic - they get more water and nutrients from mineralsoil than raised bogs (bog = a peatland poor in nutrients). They are ombrotrophic - get nutrients (but little if any) from the rain water.
The peat layer is usually 0.5-3m thick in the aapa mires, and 3-6 m thick in the raised bogs.
Above: Number of shores of lakes and ponds are swamped. The peat bed on the water's edge can
get broken and a walker may sink to water! The peat bogs like this are mainly very poor, since the water
is oligotrophic, too. See: shores!
A mire (mire complex type) can consist of several different vegetation types, the so-called mire types.
Mire types can roughly be divided in three different groups:
Pine mires: typical species pine (Pinus silvestris), cotton grass (Eriophorum vaginatum), arctic cloudberry (Rubus chamaemorus), many dwarf shrubs (like bog rosemary, Andromeda polifolia) and sphagnum-mosses (e.g. Sphagnum fuscum) etc. Usually poor, but there are some eutrophic pine mires (in Finn. = lettoräme), too.
Spruce mires: thriving usually close to the flowing water. Typical species spruce (Picea abies) and/or birch (Betula pubescens), bilberry (Vaccinium myrtillus) and herbaceous species, not so many dwarf shrubs than in pine mires, some sphagnum-mosses (like S. girgensohnii). Minerotrophic, not so poor than most of pine mires (and other ombrotrophic bogs). There are some eutrophic spruce mires (in Finn. = lehtokorpi, saniaiskorpi and ruoho- ja heikäkorpi).
Open mires (two groups):
- Open poor mires: treeless, usually dominated by different sedge (Carex) species (minerotrophic fens) or by Eriophorum species (ombrotrophic bogs).
- Eutrophic fens: richer in nutrients than other open mires, several herbaceous, Carex species and Bryales-mosses.
- Sphagnum mosses are abundant in all types, and other moss species also in eutrophic mires.
Finnish names of these mire type groups: Pine mires (in Finn. = räme), spruce mires (in Finn. = korpi), and open mires (two types): open poor mires (in Finn. = neva) and eutrophic fens (in Finn. = letto and other eutrophic mires, like lettoneva).
In the main groups mentioned above there are different subgroups (by nutrition, water economy and succession phases), which divide into mire types. There are a great number of mire types and in one mire complex type there might be several different mire types. Some mire types have been mentioned above. In the next page there are some pictures of mire complex types and mire types.
Mires are abundant in northern Finland: there are large areas in southern Lapland and central North Finland with more than 70% of mires (see a map!).
There are pine mires 40%, spruce mires 20%, open mires 25% and eutrophic fens 3% of Finland's mires. Beside this there are very many drained mires (about 50% from original mire areas are now drained especially in southern and central Finland mainly for the forest growth). In northern Finland several draining projects have failed.