Bogs are the main wealth of Polistovsky Reserve. By abundance and diversity of types of raised bogs, as well as their area, the Reserve can be considered the leader not only in the North-West of Russia but throughout Europe.
I.D.Bogdanovskaya-Gienef (1969) identifies the following five major biogeocenoses' complexes of the Polistovo-Lovatsky massif.
1. Pine-cottongrass-sphagnum biogeocenoses. In Polistovsky Reserve can be found quite often, though they have a low scale. They are associated with small, well-drained sites with a thin reservoir depth of 2-3 m. As a rule, they are formed by the dieback of the pine forest as a result of moisture increase. Pine is represented by forms Litwinowii and Willkommii. In the herb-shrub layer one can consider abundant vaginal cotton grass (Eriophorum vaginatum), shrubs - Cassandra (Chamaedaphe calyculata) and andromeda (Andromeda polifolia). The solid cover is formed by Sphagnum magellanicum, Sph. angustifolium and less by Sph. fuscum.
2. Sphagnum transitional swamps. This is one of the most common biocenotic complexes on the territory of Polistovsky Reserve. This can be found either in a form of narrow strips along the coast of mineral bogs and islands, or in a form of large plots occupied large spaces. Formed under conditions of poor drainage, with abundant influx of water from surrounding raised bogs and precipitation stagnation. Swamps of the Polistovsky Reserve have an amazingly smooth surface. Only in some case one can see over the tier of Sphagnum magellanicum and Sph. angustifolium rounded mound with Cassandra or andromeda on the background of Polytrychum strictum. Another feature of transitional bogs is almost complete treelessness. Only small solitary birches (Betula pendula) can be rarely found. The background is usually the most common plant association - Carex limosa + Menianthes trifoliata - Sph. obtusum. Associations Scheuchzeria - Sph. majus + Sph. jensenii have a common character Quite often one can find vymochiny (weak places) in which sphagnum die; then they are replaces by Sph. jensenii. Among the bogs of Polistovsky Reserve one can often observe winding lanes with reed (Phragmites australis) or swamp sedge (Carex limosa) almost devoid of sphagnum cover. Scheuchzer is of a great importance in the life of wetlands. With its strong rhizomes, it forms a solid net so that people can easily walk on the living carpet of Scheuchzer through buried streams, quite common in this ecosystem. Dead remains of Scheuchzer emit gases, mainly methane, plus they have an ability to cause floating of the surface peat layer. Floating of the vegetation cover and its bottom parts is the hallmark of transitional sphagnum swamps of Polistovsky Reserve; this forms a layer of water up to 40 cm in a depth of 25-40 cm, i.e. these swamps ingenerate scraw bogs.
3. Ridge-hollow complex (RHC). It occupies the largest area of all complexes of the raised part of the Polistovsky Reserve. Such a large spread caused by a particular topography of the massif, namely, the large area of slopes on which it develops (on slopes of 0.001-0.002 to 0.008). The main feature of this ecological community is a parallel arrangement of ridges and swampy hollows elongated in the direction perpendicular to the slope. I.D.Bogdanov-Gienef (1969) distinguished two types of RHC: 1) with the Association Sphagneta magellanici on ridges, having a limited distribution, and 2) with Sphagneta fusci on ridges, which occupies much larger areas. Within these types, she has provided a few more options for RHC, which differ by their location on a slope, length and width of ridges and hollows, the ratio of their areas, the degree of abundance, type of pine growth, and vegetation.
RHC of Polistovsky Reserve has different characters on the length of the slope; the size of hollows increases from the top of the slope to the bottom. Ridges have a height of 0.5 m and are stretched across the slope; their width can make 1 to 8.4 m. The length of ridges may reach several tens of meters. On the ridges one can found cottongrass and pine trees of various forms, sometimes they are absent or replaced by dwarf birch (Betula nana). There is an abundance of cloudberry (Rubus chamaemorus), heather (Calluna vulgaris), cassandra, andromeda. Ridges occupy from 40 to 60% of the total area of the complex. Hollows differ in sizes, degrees of flooding, the nature of the microrelief, vegetation. The width of hollows makes 1 to 20 m; they can be several to several tens of meters long. The microrelief is mostly flat, but in some types of hollows in the central part mounds can be seen; they are remains of dead buried hills. The vegetation in hollows of Polistovsky Reserve includes cottongrass, Scheuchzer, beak rush (Rhynchospora alba), andromeda, sedge, sundew, mosses (Sph. balticum, Sph. Cuspidatum, Sph. Majus). In the central part of hollows one can often find remnants of degraded ridges representing bare peat patches sometimes covered with a coating of hepatic or blue-green algae. One can consider characteristic bright yellow spots formed by lying on the surface stems of hollow sphagnum, almost devoid of leaves and slightly mucilaginized.
4. Vertex pine - sphagnum complexes. They are developing on tops of wetlands of Polistovsky Reserve, as well as on slopes with a significant bias. For these slopes one can mark strong drainage, due to which ridge-hollow complexes can not develop. These slopes are rare on the Polistovo-Lovatsky wetland massif. However, by environmental conditions and the type of vegetation they are almost similar to well-drained strips along some marshy rivers, for example, river Khlavitsa. These conditions are good for formation of a continuous cover of Sph. magellanicum sometimes mixed with Sph. fuscum. Sph. angustifolium usually grows in depressions. Also abundant growth of cottongrass is very characteristic; it covers up to 40% here. In large quantities one can find cloudberry, cassandra, rosemary, andromeda. Pine is represented by its all three wetland forms, basically by Litwinowii. The form pumina is atypical and occurs only in the form of young individuals with lower branches buried in the moss. Vertex pine-sphagnum complexes are most characteristic for convex and narrow peaks. The predominant associations are: Pinus sylvestris - Calluna vulgaris - Sph. fuscum, Pinus sylvestris - Chamaedaphne calyculata - Sph. magellanicum - Sph. fuscum. The carpet is characterized by the presence of blueberry and cranberry, the degree of coverage of which reaches 40-70%. Cloudberry is often absent, but its degree of coverage in some places reaches 70%. Spot lichens can be always found; sometimes they cover up to 25% of the surface. There are no real hollows, one can usually observe their beginnings in the form of small depressions, 1-3 m long with the Association Eriophorum vaginatum - Sph. angustifolium + Sph. balticum.
5. Lake-denudation complex in Polistovsky Reserve is located on relatively flat areas with poor drainage. It is characterized by water veins with slow flowing water and a significant concentration of gases in raised deposit layers. Lakelets can be arranged as strips or (rarely) scattered. The microrelief consists of ridges. The height of the ridge is 0.2-0.35 m, the width is about 2 m; the ridge is often split into separate mounds. Ridges occupy a much smaller proportion of the total surface than in the ridge-hollow complex (less than 25-30%). On the ridges Sph. rubellum and Sph. fuscum dominate; heather can be found in considerable amounts, as well as cottongrass and Cassandra; spots lichens are usual. Ridges can be covered with the rare pine form Willkommii; the height is usually less than 1 m, and forms pumila, wide curtains of which rise above the moss at 20-40 cm. Besides, there are also more isolated thin birches Betula pendula up to 2,5 m high.
Hollows give an original image to this complex of Polistovsky Reserve. They come in 4 types.
1. Sphagnum hollows usually have a vegetation cover formed by coenosis of Scheuchzer and sedge swamp with Sph. cuspidatum, different by their luxuriant growth.
2. Yungermanium or black hollows occupy particularly large areas in the lake bands. They have a black color due to liverworts (Gymnocolea inflata and Cephalozia fluitans). Some of these hollows are completely devoid of sphagnum, in other hollow mosses lay as separated mucilaginized spears or in small groups.
3. Denuded peat spots by their appearance are close to Yungermanium hollows but represent bare peat, which turns black when oxidized. On hot summer days, the surface of denuded spots, like black hollows, is covered with large blisters (10-13 cm in diameter and 2.5 cm in height). When they burst, the gas goes out.
4. Hollows with atypical for raised bogs vegetation occupy a small area, but have a great indicator value. The most frequent thickets are unusually high (40 cm) and dense Scheuchzer with the area 1-2 m2. Also researches found bog bean and cotton grass-herb (Eriophorum angustifolium).