Marsh is one of the most important and preserved ecosystems. Because of the hilly, troughly and woody conformation of Žemaitija national park there are lots of marsh of various sizes. The sample of a pure typical of western part of Žemaitija upland bog is the marsh of Šarnelė in the wetland of Paparčiai. Intermmediate and alkali-type low-lying marshy lands prevail in the Park. The marsh of Siberija, Šeirė, Stirbaičiai, Lieptai, Velėnijos, Sidabrinė, Paburgis, Juodupis, Briedinė and others are interesting because dense sedgy places change over to habitations of short grass and peat-moss. In the marshes of the Park botanists for the first time in Lithuania found populations of Sphagnum subnitens, Liparis loeselii, Hammarbya paludosa, Coralorchiza trifida, Listera cordata, Dactylorhiza maculata and of very rare Scolochloa festucacea. Marshes are very important for biological variaty of birds, animals and mushrooms. There lots of very rare and endangered birds nest: crane, curlew, snipe, yellow wagtail and others. Small marsh and ponds formed by beavers are important during their first 5-8 years because of biological variaty. Intermediate marsh and quag, low-lying marshy lands with European cut-sedge are preserved as important habitations of the EU.