The study presents the results of nine-year-long monitoring of the population size of amphibians (Amphibia) as one of the indicator communities used to assess the biological diversity level. The study was conducted in the Masurian Landscape Park located in Warmińsko-MazurskieVoivodeship. The obtained results demonstrated that 13 out of the 18 domestic amphibian species occurred in the area selected for research activities, including the species entered in the IUCN Red List. No clear correlation was found between the dynamics of population changes and the environmental, primarily climatic, determinants.

The paper presents the results of a 5-year study on the population size of the white stork (Ciconia ciconia L.) as one of the indicator species used to assess a biodiversity level in agricultural areas. The study was carried out in Masurian Landscape Park situated in Warmińsko-Mazurskie Voivodeship. The results demonstrated that the white stork population size was closely linked to agricultural areas, in particular, the extensively managed permanent grassland. In the years 2014–2018, even if minor changes were observed in the land use structure, the white stork population size showed a slight upward trend within the study area. In order to maintain this status, efforts should be made to preserve open landscapes (first and foremost – meadows and pastures), which are preferred feeding grounds of white stork. Consequently, potential decision as regards afforestation and housing should be made considerately.