2906543642

A GEO-ECOLOGICAL STUDY OF THE WIGRY LAKES REGION

Summary

The work presents rescarch conducted in the Wigry Landscape Park on the phenomena and processes relevant, on the one hand, to the assessment of the character of transformations in ecosystems and, on the other to the appraisal of the interaction between man and his environment.

Special attention has been given in the monograph to human economy and to those elements in the environment which are most susceptible to change. Morę stable elements have been discused in less detail. Brief descriptions have been provided of the region's climate, geomorphology, surface formations and soils. Basing on its morphometrica, lithology and land use, the studied area has been divided into geocomplexes. The adoption of 3 types of bedrock and of 7 morphometnc types of relief* as well as of 3 classes of hydrogenic areas has madę it possiblc to distinguish 189 individual geocomplexes subsumed under 27 types (tables 1 and 2, fig. 2).

The Wigry Lakes complex is surrounded by 21 villages and hamlets. Their settlement structure is presented in table 3, the demographic structure in table 4, the professional structure in table 5 and the income structure in table 6. In the immediate vicinity of Lakę Wigry, there are 470 farms, with a predominance of large (over 10 hectares) and middle-sized (5 to 10 hectares) farms. The soils are of the Iow V and VI classes (ca 70% of the area), which results in Iow crop yields, and the consequent move towards livestock production (table 7). Cereals form the dominant crop (43% of arabie land), with fodder plants (25.6%) and root crops (19.9%) following. The average number of livestock (smali animals excluded) per 100 hectares of farm land is 78.4 heads. An analysis of selected indicators points to a generally very Iow or Iow work productivity in agriculturc (table 8); the same holds true for the fishing productivity of Lakę Wigry (table 9). The services are very poorly developed: service facilitics include 3 restaurants, 7 shops, 10 kiosks, 2 dispensaries, 2 hcalth centres and 4 elementary schools.

Lakę Wigry, the central and dominant body of water in the region (2 166 hectares) is surrounded by 25 lakes of various sizes. Together they form the Wigry Lakes Group (fig. 3, table 10). The total volume ot the lakes is 336727 thousand cubic metres, and their catchment basin covers an area of ca 455 sąuare kilometres, i.e., its is fifteen times larger than the area of Lakę Wigry and all the lakes whose waters it receives. Thanks to that, the water level of Lakę Wigry has not been much aficctcd by pcriods of aridization or humidization of the climate, or by the changing elements of the water balance.

The analysis of bored monolithic sediment cores has shown that the evolution of smali dystrophic lakes („suchary") has proceedcd autnomously, which give grounds to assume that, except for the initial stage, the water level of Lakę Wigry has probably never been higher than one metre above the prescnt one. This is testificd to by the different kinds of sediments in the „suchary" and Lakę Wigry (non-carbonatc organie algo-dctrital gyttja in the „suchary", and urcy carbonate gyttja with admixtures in Lakę Wigry). Their similarity to the C¹⁴-dated sediments from the Mazurian Lakę District makes it possible to assume that Lakę Wigry and the surrounding lakes were formed ca 12000+160 years BP.

I he further evolution of the Wigry lakes has ever-increasingly been affected by human activity.