Animal and plant species depend on suitable environmental conditions for theirsurvival and reproduction. In the case study of the Ljubljana Marshes theassumption that land use diversity has a positive effect on the number of bird species was confirmed. It was found that the main ornithological areas, which were objectively selected according to the occurrence of birds of national importance, differ from other parts of the Marshes concerning some landscape structure characteristics. The analysis of the past conditions in the landscape is also important in order to detect current trends of changes. Results of the study confirm theoretical statements that the conservation of characteristic features of landscape structure plays a major role in an efficient conservation of animal and plant species in cultural landscapes.