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and especially by the presence in their waters of Chemical compounds flowing from the immcdiate catchment area. Within the catchment area of Lakę Wigry, one can distinguish 97 micro--catchmcnt-aVeas, for which an assessment has been madę of pollutant run-off, taking into account the slope of the terrain, the permeability of the substratum, the degree of plant coverage, the type of land utilization, the use of minerał fertilizers within the administrative limits of villagcs, and the amount of natural fertilizers obtained from animal husbandry (tablc 12).

The fertilizer load for each of the 97 micro-catchment-areas has been calculated by the formula:

_n Pi*+Piy F =-,

P

where: p, is the area of arabie land, p₂ is the area meadows and pastures, x is the fertilizer load per 1 hectare of arabie land, y is the fertilizer load per 1 hectare of meadows and pastures, and P is the area of the micro-catchment-area.

After the introduction of additional factors it turned out that pollutants run ofT 74.5% of the shoreline, thus totalling ca 123 tonnes of pollutants a year. This is an average of ca 1.43 kg per one metre of the shoreline, with maximum amounts excceding 35 kg per metre (table 13, fig. 5).

One of the elements that characterize geographical environment in a synthetic way is its vegetation. Potential vegetation rcflccts the biotic potential of a habitat, and actuak vegctation reflects its current State. Eleven units of potential natural vegetation have been distinguished in the studied area (fig. 6): Sphagnatelia magellanici. Vaccinio uliginosi-Pinetum, Sphagno-Piceetum, Carici elongatae-Alnetum, Tilio-Carpinetum: subboreal varicty, moist form, poor series, Tilio-Carpinetum: subborcal variety, moist form, rich series, Tilio-Carpinetum: subboreal variety, fresh and dry forms, poor series, Tilio-Carpinetum: subboreal variety, fresh and dry forms, rich series, Serratulo-Pinetum, and Peucedano-Pinetum. Thesc 11 typcs of habitat embrace 67 types of plant communitics bclonging to 16 classes. Plant communities deserving special attention are the ones of a distinct boreal or subboreal character (Acinos arvensis-Poa compressa Ass., Cirsietum rivularis_y Caricetum limosae, Caricetum lasiocarpae, Rhynchosporetum albae_% Epipactis palustris-Carex Jlava Ass., Ledo-Sphagnetum, Arctostaphylo-Callunetum, Betulo-Salicetum repentis, Serratulo-Pinetum, Sphagno girgensohni-Piceetum). Ali the plant communities of the area under study can be grouped into 9 vegatation circles determined by the evcntual plant communities (table 14) corresponding to the potential communities. It is worth noting that the various fertility series of Tilio-Carpinetum do not have their own specific substitute communities.

The regularly repcating arrangement of habitats occupicd by particular clusters of plant communities forms a basis for distinguishing plant (or vegetation) landscapes, i.e., spatial units of vegetation of a higher degree than phytocenoses. A total of 47 areas corresponding to individual vcgctation landscapes have been distingushed, subsumed under 19 types of landscapes (fig. 8, table 15) diffcring with respect to the predominance of various actual and potential communities, and their spatial situation.

The forests of the Wigry Landscape Park are one of its most precious assets. A detailed study has been madę of an area of 4 864 hectares of woodland in the Suwałki and Głęboki Bród forest inspectoratcs. The woodland includcs 13 types of forest habitats (fig. 10), of which four (fresh mixed coniferous forest, pine forest, fresh mixed deciduous forest, and alderwood) account jointly for 94.5% of the woodland area, and for 96.5% of the timber. Forests of an age bciow 80 years constiute 83% of the area, with the remaining 17% covered by older woods (fig. 12). This indicates a faulty composition of the tree stand, although this is still better than in other parts of Poland (fig. 13). The woods studied havc a high stock of standing timber (247 cubic metres per hectare), which compares favourably with the average for the wholc of Poland (155 cubic metres per hectare).

In the years 1977-1980 rcvenues from the exploitation of the forests totallcd on average 331.8 zlotys per hectare, of which 290.6 came from timber production. As there are no generally accepted methods for calculating the value of the assets and the value of non-productive (non-commercial) functions of forests, conventional indicators have been adopted. The estimated valuc of forest lands exceeds 4 million zlotys per hectare, which does not include the value of standing timber (190.2