Agricultural land in many post-socialist countries passed through a similar scenario of eminent changes in the past decades. One of the important milestones was the process of collectivisation (in 1950−1970), transformation to market-oriented economy (after 1989) and the following integration into the European Union. These changes were often attended by the process of agricultural abandonment. This paper presents an approach to the evaluation of agricultural abandonment by analysis of land use change in chosen terrain attributes (slope levels and altitude levels) context. It studies the area of a northern part of the Poľana UNESCO (United Nations Educational, Scientific and Cultural Organization) Biosphere reserve that represents mountain agricultural landscape. All of the analyses were realised in GIS (geographic information systems), based on the orthophotos that represented the land use structure in 1949, 1986 and 2006. Dramatic decrease in real usage of agricultural areas attended by the process of secondary succession was observed especially in steep slopes and higher altitude levels. To quantify the changes, landscape metrics such as class area (CA), number of patches (NP) and mean patch size (MPS) were used. Changes in landscape classes had an influence on landscape diversity. It was expressed by decrease in Shannon‘s diversity index (SDI) and Shannon‘s evenness index (SEI).