Metoda oceny środowiska przyrodniczego na przykładzie Afryki

The article includes the hypothesis stating that the differentiation of natural environment can be utilized as a synthetic index for the investigation of the relationships between the natural environment and man. The hypothesis is based on the following assumptions: (a) the phenomena, that have been observed in maps, of co-existence of differentiation of environment and concentration of population; (b) views held in literature, expressed by various specialists, that the differentiated environment encourages the development of culture; (c) on the logical assumption according to which in a situation when one of the two interrelated phenomena undergoes change, this usually entails change within the other phenomenon. Attempt was made at verification of the hypothesis on the example of the African continent. The first stage was to draw comparable maps of differentiation of the particular elements of natural environment (geological structure, relief, climate, water relations, soils and plant cover) at the scale 1 : 10 000 000, the differentiation having been calculated for the fields delimited by the geographical projection (fields of a side of 1°, the continent thus having been divided into 2,561 fields). The maps of differentiation of relief, climate and water relationships were drawn on the basis of maps of differentiation of the particular features of these elements, so they are partly synthetical, whereas maps of geological structure, soils and plant cover were based on typological maps of those elements for the African continent. Differentiation of the particular elements was presented in all the maps in five classes. The second stage was to draw a synthetical map of differentiation of natural environment on the basis of maps of differentiation of the particular elements. It is based on the ratio of classes that characterize the differentiation of elements in the given field of a side of 1°. The values received were grouped in five classes comprised within the following sections: class I 1-5¹ class II 5¹ - 5³ class III 5³ - 5⁴ class IV 5⁴ - 5⁵ class V > 5⁵ Fields grouped under class I have the least differentiated natural environment, whereas fields included in class V are marked by the greatest differentiation of natural environment. The next stage was to compare the map of differentiation of natural environment of Africa with the map of the density of population of the continent. In order to facilitate comparisons, the density of population was also presented within five classes (class I - the least populated areas, class V - areas of the largest density of population) and in identical baisic fields of a side 1°. It turned out that small density of population corresponds to the fields marked by small differentiation of environment, and the increase in differentiation is accompanied by the increase in the density of population. More than a half of fields (1,394, i. e. 54.5%) belong to the same class in both maps, and 39.1% (1,003 fields) differ only by one class. Thus, in more than 90% of cases there are no differences in classes between the differentiation of environment and density of population, or they are negligible. The article also includes the discussion about the shortcomings and virtues of the suggested method of evaluation of natural environment through its differentiation.