PROBLEMS WITH BOG AND FEN CONSERVATION IN THE BELOVEZHSKAYA PUSHCHA
Nikolai N. Bambalov,
Institute for Natural Resources
Management and Ecology,
National Academy of Sciences,
Minsk,
Belarus
REVIEW OF EXISTING BOG AND FEN TYPES
The total area of Belovezhskaya Pushcha wetlands with over 0.3 m thick peat beds amounts to 20,550 ha, of which 83.2% are fens, 13.7% raised bogs, and 3.1% are transitional bogs (mires). The thickness of the peat beds varies from 0.3 to 4.5 m, with the majority between 1 m and 3 m. Valley fens occupy 657 ha; while fens, outside of the floodplains, are widely spread and cover a total of 16,435 ha.
Figure 48. In many
places man has dug
drainage channels
in marshland (NC)
The most prevalent characteristic of the region is forested marshes that cover some 82% of all the wetlands in the Belovezhskaya Pushcha. Depending on the relief, and water supply and mineral nutrition, forest communities have formed that can be classified under various types of forest. Thus, raised bogs are characterised by sphagnum pine and birch stands, although rosemarine pine forests are also common, haircap-moss (polytric) pine forests less so. The structure of forests in fens is more diversified and includes: brook valley pine, spruce and birch stands; nettle and fern spruce and alder stands; sedge pine, spruce, alder and birch stands as well as other types.
The area of unforested marshes amounts to 3,742 ha, or 18% of the total wetland area. Large marshes, of more than 15 ha, are rare. Complexes of more than 100 ha can only be found in north-eastern Belovezhskaya Pushcha. The remaining territory features only small fragments (frequently, less than 1 ha) of unforested marshes among forested complexes. These are predominantly of the fen type (98%). One third of the open fens do not host any arboreal species; the rest display, approximately in equal proportion, willow shoots (most frequently 15% to 20%), young white birch (5% to 15%), and black alder (5% to 20%). Occasionally, single trees of white birch, black alder and pine, over 20 years old, are found. The timber stock is frequently below 10 m3/ha.
ORIGIN OF THE DIFFERENT TYPES
Figure 49. Bog Arum, (Calla palustris)
a characteristic plant species
of the mesotrophic fen mires (CO)
The peat bogs in the Belovezhskaya Pushcha originated in various Holocene periods, by overtaking the then-existing water bodies, and swamping mineral soils. However, good data on the geological age of bogs is very scarce.
The geomorphology of the Belovezhskaya Pushcha bogs is diverse. Thus, the Kladovo, Krapivnitsa, Glubanets, and Blazhki bogs, along the Kolonnaya River, and the Shkodinka, Panasyuki, Rozhkovo, Zlyatino, Khmelevshchizna, and Muroch ones are confined to the floodplains of rivers and streams. The Glenboks, Popelevo, Grinki, and Osinniki bogs are on higher-level terraces, above the floodplains. The Chepelevskoie Bagno and Gnilitsa bogs occupy discharged craters, while the Abramovo and Podmoshie bogs flow through craters of a fluvioglacial plain. The large Dikoie bog originated at the watershed of the Yaselda, Narev, and Nebuzyanka riverheads, in a vast flow-through valley; and the Diky Nikor bog was formed on the right bank of part of the Narevka riverhead.
THREATS AND CONSERVATION ASPECTS
The main factors that pose a threat to the conservation of the valuable open mesotrophic bogs (mires) in their present status are the natural processes of plants and vegetation succession plus drainage reclamation..
Figure 50. The fen mires of the
Dikoie Bog harbour one of the
world's largest populations of
the Aquatic Warbler
Acrocephalus paludicola) (NC)
Natural successions are problematic for such open "meadow" bogs, since these bogs are at a stage where they can readily change following variations in the conditions of water-mineral nutrition. For example, the vast sedge expanse of the Dikoie bog is beginning to be overgrown, in some places, by peat moss. This is indicative of the initial stages of transition of the bog towards a more eutrophic type of nutrition, and the replacement of sedge phytocoenoses with sphagnum moss types. Should the drainage intensify due to the reclamation of adjoining territories, the mesotrophic type of nutrition may change to that of a eutrophic type, and then the sedge phytocoenoses will start to be replaced by Arundineae or members of the Salicaceae family. Such patches have already appeared in the vicinity of some previously constructed canals. In either event, the loss of valuable mesotrophic sedge marshes would inevitably lead to the extinction of a rare and world-wide threatened bird, the Aquatic Warbler (Acrocephalus paludicola), along with other species of animals and plants.
A still more dangerous threat to the wetlands and natural complexes of the Belovezhskaya Pushcha, and its adjoining territories, is land drainage reclamation. The drainage of the Glubyanets and Diky Nikor complexes has resulted in the decrease of a relict tree species, the Silver Fir (Abies alba), in a small woodlot ("Tisovka Reserve") at the edge of the territory of the Belovezhskaya Pushcha, the only location where it grows naturally in Belarus. Drainage activities that directly adjoin the wilderness protection forests cut into them like a wedge. Consequently, within the 3 km zone of influence of these melioration systems, the fall in the ground water table (GWT) has had a disastrous effect upon the phytocoenotic structure and productivity of the Pushcha forest stands.
The most devastating effects can be seen on spruce and broad-leaved spruce stands, especially on old-growth stands (typically 120 to 160 years old). Root fungi have developed on the spruce stands due to changes in the natural hydrological regime. The trees, weakened by the fungi, were then attacked by bark beetles, the combination leading to the mass withering of spruce stocks.
Presently, the ground water level in the area is stable, and root system adaptation of all the stand types has occurred over recent decades. Hence, a significant change in the GWT in either direction would not be tolerated. Patches of former agricultural lands in the Glubyanets and Diky Nikor tracts, recently jointed to the territory of the Belovezhskaya Pushcha, should, according to our recommendations, be left under natural growth conditions and self-waterlogging.
Another large site influenced by excessive anthropogenic impact is the Dikoie bog. Geological forays have been initiated there on some 13 occasions, and to a certain extent the peat beds have been excavated. Scattered plots all over the bog area are planed to excavation and, hence, their exploitation would be a threat to the very existence of the bog. The functioning of the southern part of the bog has severely suffered from drainage land reclamation in the upper reaches of the Yaselda River.
The analysis of the current status of the Belovezhskaya Pushcha wetlands, including their Support Zone, reveals that all the systems are hydraulically linked with the Pushcha territory, and have been disturbed to varying extents by anthropogenic interference. Drainage operations and peat mining results in the degradation of bog vegetation cover, fire initiation, and the extermination of rare species of plants, birds, and other animals. In connection with this, a set of arrangements need to be drawn up with the aim of preserving and optimizing the management of the Belovezhskaya Pushcha wetlands.