Responses of small mammals to the forest management in the Białowieża Primeval Forest

45—59 [With 4 Tables & 6 Figs.] Trapping of small mammals was carried out in the autumns of the period from 1976—>1979 over 14 hectares of mixed coniferous forest of varyied age within the Białowieża Primeval Forest. The trapping lines ran along the boundaries and through the middle of each forest belt of the given age class. The oldest age classes of planted treestands and natural old-growth 'stand (over 100 years old) were characte-rized by a high similarity index of occurrence of mammals. The groups of mammals in the younger age classes of treestands and the narrow belt of old-growth stand are characterized by low indexes of similarity to mammals from other classes and in relation to each other. This points to degradation of the narrow old stand belt as a habitat for mammals. Succession of mammals in a complete clearing lasts for a shorter time than attainment of maturity by the tree stand and ends in the 20-year old treestamd. This takes place in two phases. A. 1 to 14 years as from time of planting the clearing: the number of mammal species and numbers of mammals increase (at the beginning almost zero) to a maximum in the 11—'14 year old treestand. B. 15 to approx. 20 years: non-forest species disappear, and quantitative pro-portions for different species of mammals, typical of an old coniferous forest, are formed. The following four species of mammals were found in the natural old coniferous stand: Clethrionomys glareolus, Sorex araneus, Sorex minutus and Apodemus flavicollis