The nature of the protected area is primarily characterised by the bog, which is surrounded by various types of forest and is the heart of the area’s hydrological cycle. The protected raised bog consists of the Mukri bog in the north and the Ellamaa bog in the south. The bogs are named after nearby villages of the same name. The two bogs are often jointly called the Mukri bog.
The raised bog is named after its thick layer of peat. This is why bogs are always higher than the area surrounding them. The raised bog is the last development stage of bogs, where the layer of peat is so thick that the roots of plants cannot reach the nutrient-rich mineral soil or groundwater. Peat is partially decayed vegetation, an organic sediment that forms in an environment that is high in water, low in oxygen and acidic. Peat is low in nutrients, which is why the special vegetation of bogs primarily receives its nutrients from the dust in precipitation. The peat layer of the Mukri bog is on average 4.6 m thick and the deepest layers reach 8.5 m.
The bog is the largest habitat type of the Mukri Nature Reserve, accounting for a little more than half of the protected area, i.e. 51%. Transition mires occur in the southern part of the Ellamaa and the Mukri bog, some of which are natural and some having formed in former peat extraction sites. The central part of the bog is a wooded bog and on its outskirts is transition and fen woodland.
The Mukri bog has remained untouched by major human activity and has therefore largely maintained its natural way of life. Although peat has been extracted from here as well, it was done by hand and in a small area, which limited the extent of damage. Peat was extracted here for animal bedding and heating between 1920 and 1950 by the Kobra peat cooperative, individual producers and the local collective. Peat extraction is evidenced by ditches in the part towards Eidapere and little peat pits and peat stacks can be seen beside the boardwalk leading from the gravel road directly to the lake. In the western part of the bog, preparations have been made for peat extraction. In the southern part are 55 hectares of old quarries where peat was dug with spades. In the last century, before the protected area was formed, drainage ditches were dug in the area, which have had a negative impact on the environmental values of the area. As a result, some of the bog pools have closed up. There is a plan to close the ditches in the future in order to restore the original hydrological regime and habitats in the areas affected by human activity.
Peat absorbs and retains a great deal of water. In natural bogs, peat is on average 90% water. Therefore, most of the protected area’s water is in the peat, which accumulates water from precipitation. The water draining out of the higher central part of the Mukri bog flows into the Imsi Stream and Vaki Stream and the Massu River. These running waters flow into the Vändra River, which carries the water through the Pärnu River into the Gulf of Riga in the Baltic Sea. The hydrological cycle of the bog has a major impact in preventing floods in the surrounding areas as well as alleviating droughts.
The Mukri bog has numerous bog hollows and bog pools. A bog pool is a little body of free water in peat soil. Bog pools are characteristic to older bogs. Bog hollows are lower and more watery spots on the surface of the bog, which are still covered in vegetation.
The northern part of the Ellamaa bog has several lakes, the largest being the 2.2-ha Lake Eidapere. A swaying sward has formed on the shore of the lake. The lake is 340 m long, 100 m wide and the well-structured shoreline is 1605 m. Similarly to typical bog lakes and bog pools, the water of Lake Eidapere is brownish due to peat and humic substances. Humic substances are water-insoluble collections of organic matter in peat. Such bodies of water are the habitat of rare plankters found in northern regions. A plankter is a tiny organism that floats in water. Lake Eidapere has three peat islets, which are not connected to mineral soil. The lake is abundant in white waterlilies and dwarf white waterlilies. Both protected species are a wonderful sight when in bloom (from June to July).
The most common forest communities in the Mukri Nature Reserve are transition mire and bog forests, totalling 234 ha, which make up 11% of the protected area. These forests are a suitable habitat for the western capercaillie. In the northern part of the protected area and on the outskirts are old-growth forests, which account for 3% of the protected area. Old-growth forests are old forests with little human impact where favourable habitats have developed over time for many currently endangered species. There are endangered species among the mosses, lichens, fungi and animals.
Old-growth forests also include grassy spruce forests, which account for just 1 ha of the Mukri Nature Reserve. Such forests grow in areas with a good water supply, where groundwater flows close to the surface and the soil is nutrient-rich. These are forest stands with rich soil, consisting mostly of spruces.
To the south of the Mukri bog is an 11-ha community of paludifying forests and deciduous bog forests. This forest habitat is also characterised by the closeness of groundwater to the ground, which can often reach the surface during spring high water. In such conditions, so-called stem sods form around the lower part of tree stems.
The protected area has also severely drained peatland forests with a considerable amount of thick down timber, stubs and other elements that increase the diversity of forest habitats. Often, these elements are important, especially as habitats of rare species, such as mosses and lichens.
Meadows – semi-natural grasslands
Meadows, or semi-natural grasslands, have become rare, which endangers the habitats and feeding areas of the species associated with these biotic communities. In the eastern part of the Mukri Nature Reserve, there are nearly five hectares of meadow with meadow foxtail and great burnet. The grassland has probably been used as a field and been moderately fertilised, which has reduced its species composition. In order to preserve the biotic community, it is necessary to continue human activity, i.e. mowing.
The Mukri Nature Reserve is home to many species, including protected ones. Conservation objectives have been established in Mukri for four protected plant species. These are the ghost orchid of protected category I and the poor sedge, the early coralroot and the lesser twayblade of protected category II.
Other protected plant species in the area include the bog orchid and the slender cottongrass of protected category II and the creeping lady’s-tresses, the northern firmoss, the dwarf white waterlily, the white waterlily, the heath spotted-orchid and the common spotted-orchid of protected category III.
Three bird species – the black stork, the western capercaillie and the northern goshawk – are under special observation in the Mukri Nature Reserve.
Must-toonekurg on rändlind, I kaitsekategooriasse kuuluv toonekureline. Liik on Eestis kriitilises seisundis, tema arvukus on vähenenud 1980. aastate alguse 250 pesitsevalt paarilt praeguse 40–60 paarini. Põhjuseks on sobivate toitumisalade ja elupaikade kadumine inimtegevuse tagajärjel. Must-toonekurele sobib elupaigaks vaid vana looduslik mets varjuliste vooluveekogude läheduses. Lisaks must-toonekurele saavad sellistes vanades metsades elada veel kuni 400 ohustatud liiki. Must-toonekurge nimetatakse teiste ohustatud liikide suhtes katusliigiks, sest must-toonekure kaitsega on hoitud ka kõik teised sealsed liigid.
Tuntuim Mukri must-toonekurg on aastast 2008 noor isalind Oss ja tema poeg Ossipoeg. Nemad said 2008. aasta suvel uurijatelt endale nimed ja selga raadiosaatjad. Raadiosaatja abil on jäädvustatud mõlema linnu rännakud aastal 2008 ja Ossi liikumised kuni 2011 aastani. Need teekonnad ja lisainfo koos piltidega (avanevad klikkides linnu nimel) on vaadeldavad siin.
Metsis on paigalind, kes on väheneva arvukusega II kaitsekategooriasse kuuluv kanaline. Metsis on tuntud isaslindude kevaditi toimuvate pulmamängude poolest. Mukri looduskaitseala on oluline metsise eluala, sest jääb teiste lähedalolevate metsisealade vahele ühendavaks koridoriks. Mukri raba ääres on kinnitust leidnud kaks mänguala kuue kukega.
Kanakull kuulub II kaitsekategooriasse ja on Eestis hajusalt levinud paigalind. Tema arvukus on oluliselt vähenenud intensiivse metsamajanduse tõttu. Mukri alal on kanakull pesitsenud pikema aja jooksul ja seda olukorda püütakse säilitada. Piirkond on kanakullile soodne, sest tegu on olulise metsisealaga, kes on kanakulli üheks saakobjektiks.
Liigi kohta loe lisaks ajakirjast Eesti Loodus.
Teistest kaitsealustest loomaliikidest elavad Mukri looduskaitsealal II kaitsekategooriasse kuuluv laanerähn ning III kaitsekategooria liikidest teder, hallõgija, punaselg-õgija, hoburästas, männi-käbilind, punajalg-tilder, mudatilder, heletilder, sookurg, hiireviu ja raudkull.